Studies of the Sulfur Dioxide Insertion of Some Metal Complexes

Home , Carbon disulfide, Dicyclopentadiene, Molybdenum hexacarbonyl, Sodium amalgam

This dissertation has been microiihned exactly as received 66-6231

BIBLER, Jane Pycraft, 1939- STUDIES OF THE SULFUR DIOXIDE INSERTION OF SOME METAL COMPLEXES. The Ohio State University, Ph.D., 1965 Chemistry, inorganic

University Microfilms, Inc., Ann Arbor, Michigan STUDIES 0F THE SULFUR DIOXIDE INSERTION OF SOME METAL COMPLEXES

DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By Jane1 Pyc raft Bible-r, A.B., M.S.

The Ohio State University 1965

Approved by

(a )w a a *& u Advise/ Department of Chemistry ACKNOWLEDGMENTS

The successful completion of this study is a direct reflection of the efforts of several groups who have con tributed sppport in various ways during my graduate career. In particular, I have selected three which have been most instrumental in the progress of this work. First, I wish to express my appreciation to my family for their patience and understanding. Specifically, I thank my husband, Ned, for his devotion and advice, and my mother, Mrs, Pauline Pycraft, for typing the first and final drafts of this dissertation. Second, I am indebted to the responsible members of the scientific community who, throughout my studies, have provided encouragement and guidance, I especially thank Dr. A, A. Wojcicki, my adviser, for his assistance and counsel during the course of the research and in the pre paration of this manuscript. Finally, I wish to acknowledge the financial support of The Ohio State University and the Petroleum Research Foundation, VITA

June 3» 1939 «... Born — Lorain, Ohio 1961 ...... A«B., Miami University, Oxford, Ohio.

1961-1963 ...... Teaching Assistant, Department of Chemistry, The Ohio State University, C olumbus, Ohio.

1963-1965 ...... Research Fellow, Department of Chemistry, The Ohio State University, C olumbus, Ohio. 1 9 6 4 ...... M.S., The Ohio State University, C olumbus, Ohio.

PUBLICATIONS

J.P. Bibler and A. Wojcicki, J, Am. Chem. Soc., 8 6 , 5051 (1964)

FIELDS OF STUDY

Major field; Inorganic Chemistry. Dr. Andrew A. Wojcicki

iii CONTENTS Page ACKNOWLEDGMENTS...... ii VITA ...... iii PUBLICATIONS ...... iii FIELDS OF STUDY ...... iii TABLES ...... v FIGURES . . / ...... vii

INTRODUCTION ...... 1 EXPERIMENTAL ...... 28 Starting materials Preparation of sulfonyl derivatives Preparation of acetyl derivatives of 7t-C5 H5 Fe(CO)2 CH3 Reactions of sulfonyl compounds RESULTS AND DISCUSSION ...... 101 Investigation of the sulfonyl derivatives Investigation of the acetyl derivatives of tc-C5 Fe(CO)2 CH3 CONCLUSION ...... 180 APPENDIX I ...... 182 APPENDIX I I ...... 203 APPENDIX I I I ...... 208 BIBLIOGRAPHY ...... 211 TABLES

Table Page 1. Infrared Frequencies of Free and Coordinated S02 ...... 24 2. Analyses for Iron and Molybdenum Sulfonyl Derivatives ...... 64 3. Analyses for Mercury Sulfonyl Derivatives...... 69 4. Analyses for Acetyl Derivatives of ti-Cj H5 Fe(C0 )2,CH3 ...... 87 5. Some Physical Properties of Iron and Molybdenum Sulfonyls ...... 110

6 . Proton Magnetic Resonance Spectra of H-C5 H5 FeCC0)2> R ...... 112 7. Cyclopentadienyl Proton Chemical Shift Position for it—C5 Fe{C0)2 S02 R ...... 115

8 . Infrared SO Stretching Frequencies of Some Sulfonyl Compounds ...... 120 9® Comparison of Infrared Absorption Fre quencies of Tt-C5 H5 Fe(C0)2 SCBj . 7C-C5 H5 Fe- (C0)2 C ^ , and 7C-C5 H5 Fe(C0)2 S0 2 CH3 ...... 124 10. Infrared CO Stretching Frequencies of ti—Cj Hj Fe(CO)2 R Complexes ...... 126 11. Proton Magnetic Resonance Spectra of 7t-C5 Hj Mo ( CO )3 R ...... 136 12:. Some Physical Properties of Mercury S u l f o n y l s ...... 142 13. Proton Magnetic Resonance Spectra of Mercury Derivatives, RHgR' ...... 144

v TABLES, CONTD.

Table Page 14. A Comparison of the Infrared Absorption Frequencies of C6 Hg HgS02 C6 H5 and C6 H5 HgSC6 H , ...... 155 15. Infrared SO Stretching Frequencies of RHgS02R ...... 156 16. Infrared Absorption Frequencies of Iron-Tin Complexes ...... 158 17. Infrared Absorption Frequencies for Compounds Prepared from NaMn(CO)5 and RS02 C l ...... 162 18. Some Physical Properties of the Acetyl Derivatives of C5 H5 Fe(CO)2 CH3 .... 174 19. Proton Magnetic Resonance Spectra of 7C-C5 H5 Fe(CO)(COCH3 )PR3 ...... 176 20. Infrared CO Stretching Frequencies of tc-C5 H5 Fe ( CO ) ( COCB3 ) PR3 C omplexe s ...... 177 FIGURES Figure Page 1. Similarity of Carbon Monoxide, Sulfur Dioxide and Their Compounds ...... 18 2. Apparatus for the Preparation of [ic-C5 Hj Fe(CO)j[] 2 and [te-Cj Hj MoCCO)£] 2 .... 29

3. Apparatus for Drying and Condensing S02 . . . 35 4. W Irradiation Apparatus ...... 38

5. Possible Structures of Tt-C5 H5 Fe(CO)2 S02 CE^ R . 114

6 . A Comparison of the MUR Spectra of C5 H5 Fe(CO)2 CI^ Cg H5 and CjHsFeCCO^- S02 CHa C6 % 118 7. A Comparison of the Infrared Spectra of C5 H5 Fe(CO)2 CH5 and C5 % Fe.(CO)2 - S0 2 CH3 ...... 123

8 . Proton Magnetic Resonance Spectra of the Methyl Protons in C2 H5 HgS02 C2 H5 ...... 149 9. A Comparison of the Infrared Spectra of Cg H5 HgSCg H5 and C6 H5 HgS02 C6 H5 ...... 154

vii INTRODUCTION

The chemical literature of the last ten years contains a rapidly increasing number of examples of the so-called insertion reaction in organometallic chemistry. Although some aspects of the insertion reaction are not yet under stood, it has already become an extremely useful tool in chemical syntheses. Insertion, as Heck (1) notes in a recent review, is generally described as the addition of a covalent metal compound, M-Z, to a neutral unsaturated molecule, :Y, to form a new complex where :Y is ultimately bonded to both the metal and the atom which was initially attached to the me tal.

M-Z + sY ------> M-Y-Z (1)

Equation (1> is the simplest representation of the insertion reaction. It does not consider the role of sol vent, if any, in the mechanism, the nature of M-Z, or the nature of the final product, M-Y-Z. Nevertheless, it is relatively good representation of some of the less compli cated insertion reactions because insertion may be des cribed as merely a special case of an addition reaction involving a covalent metal compound. The molecule :Y may be carbon monoxide, an acetylene, an olefin, a carbon-nitrogen compound, a conjugated diene, a carbene, or several other unsaturated compounds. Cova lent metal compounds which are known to undergo insertion contain a reactive metal-hydrogen, metal-metal, metal- carbon, metal-oxygen, metal-nitrogen, or metal-halogen linkage. Of particular interest in this investigation are those reactions involving insertion into a metal-carbon bond. The first example of such an insertion reaction was reported by Coffield and co-workers in 1957 o They found that methylmanganese pentacarbonyl reversibly absorbs carbon monoxide to form acetylmanganese pentacarbonyl. (2 ) Ethyl- and phenylmanganese pentacarbonyl react with carbon monoxide in the same manner. Further investigation on the methyl derivative (3) using C14-labeled CO showed that a carbon monoxide already coordinated to the manganese is being inserted rather than the incoming carbon monoxide.

CHj Mn(CO)5 +C*0 ---- } (CH3 C0)Mn(C*0)5 (2)

The alkylcobalt tetracarbonyls react analogously with carbon monoxide, forming acylcobalt tetracarbonyls. (4) Like that of the corresponding manganese compounds, the

reaction is reversible. (5 ) HCo(CO),, +G0 (200)00(00),, (3)

The cobalt complexes are much more reactive than the man ganese compounds, however, and must be studied below

-35°Ge (6 ) Acetylcobalt tetracarbonyl dissociates about

2 2 5 0 times faster than acetylmanganese pentacarbonyl at 25°C., the difference between the solvents, ether and the diethyl ether of diethylene glycol, being neglected. (5 ) Consequently, much more is known about the manganese system. Insertion of carbon monoxide takes place with many other transition metal alkyl and aryl complexes. The methyl derivative of cyclopentadienyliron dicarbonyl will add to CO to give the acetyl compound. (2)

m-C5 H5 5*6 (0 0 ) 2 CH, +00 --- > m-C5 ^ Fe(C0)2 (C0CH3 ) (4)

Unlike the acyl derivatives of manganese and cobalt, acyl- iron complexes completely decompose on heating rather than undergo decarbonylation to form the alkyl derivatives. (2 ) king has recently been able to convert a large variety of these acyl complexes of iron to alkyls or aryls with the use of ultraviolet light. (7 )

ir-C5 H5 5'e(CO)2 (C0C6 K; ) — 7t-C5 H5 Fe(C0)2 C6 Hg +00 (5)

Interestingly enough, although hydrogen-containing alkyl and aryl cyclopentadienyliron dicarbonyls readily and reversibly insert carbon monoxide, there is no evidence that the corresponding perfluoroalkyl and -aryl derivatives will do so. There are many examples of the decarbonylation of perfluoroacyl derivatives of other metal ions. (7 * 8 , 9, 10) Some perfluroacylcobalt tetracarbonyl compounds have been obtained (8 , 9 , 1 0 ) at low temperatures from Na[Co(G0)Jj and 0» where n is equal to 2, and 7« Like the alkyl cobalt complexes, these undergo spontaneous decarbonylation to produce the corresponding perfluoroalkyl derivatives. Also, molybdenum derivatives of perfluoroacyls can be decarbonylated using ultraviolet light (7 )» "but the acyl starting compounds must be prepared by reaction of the sodium salt of cyclopentadienylmolybdenum tricarbonyl and an acyl chloride rather than by 0 0

insertion. (7 )

NaMo('C0)3 05 Hg +C3 F7 C0C1 >NaCl+(C3 F7 C0)Mo(C0)3 C5 Hg (6 )

( C3 F7 GO ) Mo ( GO ) C5 Hg — ^ C3 F7 Mo ( GO )3 C5 Bg +C0 ( 7 )

Only one example of insertion into a perfluoroalkyl complex has been reported*--' (11) The heterogeneous reaction between either sodium halides (except NaF) and hydrogen

halides (except HF) and jjc-Cg Hg Co(G0)2 C3 F7J +C104 leads

to dimeric compounds, jjc-C5 Hg Go(C0G3 F7 )xj2 , which contain halogen bridges. It is believed that the higher charge on the metal in this Co(III) complex results in a weaker carbon-to-metal bond, thereby making insertion between Go and 5 the -C5 F? group possible. Eeduction of the charge on the central metal atom apparently increases the M-C^, bond strength enough to prevent insertion, as in the case of Fe(II) and Co(I) complexes. Hieber, et al (12) have shown that acylrhenium pentacarbonyls, prepared from pentacarbonylrhenate(-I) and acyl chlorides, evolve one mole of carbon monoxide on heating, forming the corresponding alkylrhenium pentacarbonyls. An interesting deviation from normal decarbonylation reactions is reported by McCleverty and Wilkinson, (13) They heated cyclopentadienyl(propionyl)tricarbonylmolybdenum(II), x-C5 HjMoCCO^ (C0C2 ) , and found that two pro ducts were formed. The compound recovered in largest yield was the expected ethyl derivative, Tt-C5 H5 Mo(CO)3 C2 H5 • In addition, however, the -C2Hj group migrated, presumably by a free radical mechanism, to the cyclopentadienyl ring form ing some jj(7t—C5 C2 H$ )Mo(CO)3J 2 . The tungsten analog yield ed only the expected m-C5 Hg W(CO)3 C2 H5 . k-C5 H5 Mo(CO)3 (COCjjE* ) 80-100°G_.^ ^ 5 1% Mo(C0)3 C2 H5 + CO

+' [(7r-C5 HvC2 H5 )Mo(C0)5] 2 (8 )

Recently, Heck (14-) has prepared some hexacoordinate rhodium(III) and iridium(III) complexes, Methylrhodium chloroiodocarbonylbis(tri-n-butylphosphine) and methyl- 6 rhodium diiodocarbonylbis(tri-n-butylphosphine) in methyl ene chloride solution slowly absorb one mole of carbon monoxide at atmospheric pressure to form the corresponding acetyl derivatives.

GHj RhIClCCO) [P(n-C4 H* )3] 2 + 0 0 -- * (CH* C0)RhIClC00) [p(C* H* )J 2 (9) The iridium analog did not take up CO under, the same con ditions but it is believed (14) that it would at higher temperatures and pressures. Mono- and dialkyl derivatives of dihalobisphosphine compounds of nickel, palladium, and platinum also undergo the carbon monoxide insertion reaction. (15) In partic ular, insertion with the compounds trans-MXR pP(C2 Hj )3J 2 , where M is palladium or platinum, X is chloride, bromide, or iodide ion, and R represents an alkyl or aryl group, has been studied most extensively. Carbonylation proceeds readily with the palladium compounds at room temperature and atmospheric pressure. For the platinum compounds more extreme temperature (90°C.) and pressures (50-100 atm.) are necessary. The reactions of mono-alkyl, deriv atives are essentially straightforward and yield the expected acyl products. trans-PtlCEt fp(0, a, ),'[, + CO ^ toans-PtlCOOCH, )-

[p CCj H,),], (10) 7 A dialkyl derivative of platinum, trans-Pt(OH3 )2 JjP(C2 H5 )3] 2 > reacts with. CO to give an unstable platinum carbonyl com pound and diacetyl. It is believed (15) that the insertion occurs through a 5- or 6 - coordinate intermediate. This would explain the greater reactivity of palladium complexes. Although no 5— coordinate platinum or palladium derivative of the formula

MXg (CO) [p(C2 Hg )3J 2 has yet been reported, Pt(C0)2 F2 [p(C6 % )3J (16) is known to be stable. Also, cobalt compounds,

CoBr2 (CO) JjP(C2 Ej )3] 2 , have been isolated, (15) A similar species might well be the intermediate in the carbonylation of Pt or Pd complexes. It has already been shown that after the reaction of methylmanganese pentacarbonyl with carbon monoxide, the entering molecule of carbon monoxide is not found in the acetyl group of the product. (5) Thus, it is to be ex pected that coordinating molecules other than CO can react with an alkyl carbonyl complex and result in the change of a terminal carbon monoxide to an acyl CO. Methylmanganese pentacarbonyl reacts with a variety of nucleophiles, L, to give products of the general formula (03% C0)Mn(C0)4 L or

(CH, CO)Mn(CO)3 I* . Ligands which effect this reaction in clude cyclohexylamine, N-methylcyclohexylamine (17)» triphenylphosphine (18), tri-n-butylphosphine (19)? triphenylphosphite (18), triphenylarsine (18, 1 9 )? and triphenyl- stibine (1 9 )»

CHjMn(CO)5 + L -----) (CHj CO)Mn(CO)*L (11)

The phenyl derivative, however, only forms the benzoyl complex when L is butadiene, (20) Otherwise, a compound of the type C6 H, Mn(CO),, L results. (19) Alkylcobalt tetracarbonyls also react with triphenylphosphine (2 1 , 2 2 ) and phosphites (2 3 ) to give very stable acylcobalt tricarbonyl derivatives,

ECo(GO)if + PR, ------> (RCO)Oo(00)3 PR, C 1 2 )

Studies on the reaction of alkylmanganese carbonyl and ligands other than carbon monoxide have provided in sight into the mechanism of the insertion reaction. The rate of the reaction of methylmanganese pentacarbonyl with carbon monoxide was studied initially by Galderazzo and Cotton. (24) This reaction was shown to be first order in carbon monoxide and first order in CH,Mn(CO)5 , but the data did not distinguish between two possible mechanisms. The coordinated carbonyl could insert between the metal and the methyl group (or the methyl group may migrate onto an adjacent CO) before attack by the incoming carbon mon oxide .

CH,Mn(CO)(CH3 CO)Mn(CO)lt — (CH, CO)Mn(CO)5 (13) Also the incoming 00 could force either the insertion of a coordinated carbonyl or migration of the methyl group.

--9*3 OC' CO CHj Mn(C0)5 + 00 ^(CH, C0)Mn(00)5 CO (14) 0 0 00 CO

The mechanism suggested by the investigators involves a direct attack on 0^Mn(C0)5 by carbon monoxide simultaneous with an intramolecular rearrangement to form (OBj C0)Mn(C0)5 .

Since the range of experimental concentrations was limited in the previous study by the solubility of carbon monoxide in the solvents used, the mechanism was later tested for reactions of CHjMn(C0)5 with other more soluble nucleophiles. (18) The nucleophiles used were cyclohexylamine, triphenylphosphine, triphenylarsine, N-methylcyclohexylamine, and triphenylphosphite. Methylmanganese penta carbonyl undergoes the insertion reaction with cyclohexylamine in tetrahydrofuran to give (OHj C0)Mn(C0\ (C6 E, 1 KHg) at a rate independent of the amine concentration. In n-hexane, however, the reaction was first order in both re actants. The reaction with triphenylphosphine and triphenyl phosphite gave rates dependent on ligand concentration in

THF. However, at high concentrations the rate approached a limiting value similar to that for cyclohexylamine. With

N-methylcyclohexylamine in tetrahydrofuran the reaction did 10 not go to completion, but the rate of approach of equilib rium was first order in CH3 Mn(CO)5 . The results are explained by a two-step mechanism involving a solvent-assisted dissociation, common for many octahedral complexes. (25* 26, 27) The breaking of the

CHj Mn(C0)5 — S ' (OHj C0)Mn(C0)i,S (CH3 CO)Mn(CO)* L (15) S = solvent L = ligand manganese-to-methyl bond appears to be the critical step in the mechanism. If a weak bond could be formed between the methyl group and an adjacent carbonyl, the cleavage of the Mn-CE^ bond would be facilitated. Migration would not be complete until a solvent molecule or another new ligand enters the coordination sphere. Apparently the nucleophile assumes the role of the solvent only when the coordinating ability of the solvent is very low (viz. n-hexane). This mechanism also accounts for the observation of Calderazzo and Cotton that the rate of reaction of CH3 Mn(CO)5 and CO is first order in both reagents, since the concentration of CO in their experiments was sufficiently low to make the second step of the reaction rate-determining. The question left unanswered by this mechanism is whether the reaction involves migration of the methyl group onto one of the carbonyl molecules or actual insertion of a molecule of CO, already bonded to the manganese, between 11 the metal and the methyl group, To solve this problem, Mawby, Basolo, and Pearson (28) studied the decarbonylation of trans-CCHj C0)Mn('C0\ P(C5 H5 )3 . By the law of microscopic reversibility, the reverse of this process, i.e, insertion, must proceed by the same mechanism. Thus, the investigators were essentially study ing the insertion mechanism. They reasoned that if decar bonylation proceeds by the reverse of insertion, the product would be trans-CHj Mn(CO\P(C 6 H5 )3 . (See Equation 16) If, however, decarbonylation proceeds by the reverse of the migration of the methyl group, the product would be cis-CEt Mn(C0)fc P(Cfi Hq), . (See Equation 1?)

GEr V "C=0 CH, C| ^-00 - I ^ -CO oc ----- 00 OC _ m " ---- CO • (16) oc ^ I insertxon { + C 0 P(0SH5 )3

„ck3 \ 0=0 CO I -CO x. I —CO O C Mn" -- CO — -> GEy M h - CO (17) \ OC** I methyl oc ^ | +C0 ^ P(C6 H5 )3 migration P(0SH,),

( The product of decarbonylation is actually the cis isomer, indicating that the mechanism for the manganese system could, indeed, involve methyl migration. The possi- 12 bility still exists, however, that the trans isomer is actually formed but is unstable and undergoes very rapid rearrangement to the cis compound. Therefore, trans-

CHj Mn(CO)4 P(C6 H5 )3 must be prepared (this isomer has not been reported) and shown to be a stable complex under the conditions of the decarbonylation before it can be defi nitely stated that the process is the reverse of methyl migration. As expected, metal alkyl and aryl complexes will add to other unsaturated molecules. Recently Stone and co workers reported the addition of methylmanganese penta carbonyl to fluorinated ethylene derivatives. At 90°C. or at room temperature in ultraviolet light, tetrafluoro-

ethylene reacts with OH3 Mn(CO)5 forming 1,1,2,2-tetra- fluropropylmanganese pentacarbonyl. (29) Methylrhenium pentacarbonyl also adds to unsaturated fluorocarbons but requires higher temperatures than the manganese analog.

0 % M ( C 0 )5 + CF2 =CF2 ------> OH, OP2 GP2 M(CO)5 (18) M=Mn, Re

In addition, whereas methylmanganese pentacarbonyl will add to only one molecule of tetrafluoroethylene, the rhenium carbonyl is capable of absorbing two molecules to give

CH3 (C3?2 )4 Re(CO)4 . (30) The unsaturated fluorocarbons are very reactive toward metal-metal bonds as well. In 1962, Beg and Clark (31) reported the reaction of hexamethylditin and tetrafluoroethylene.

(CH^Sn*, + CF2 =CF2 — g§x~— > (OH, )3 SnC8!^Sn(0%)3 (19)

The compound (CH3 )3 SnMn(C0)5 also reacts with C2 F,, when irradiated with ultraviolet light to give several products, one of which is (CHj )3 SnC2 F%Mn(C0)5 . Another product has been identified as £(00)^ MnCF=CF2 2 . (32)

(CH* )3 SnMn(C0)5 + C2 F^ - ^ ^- 9 (CH5 )3 SnC2 F*Mn(C0)5 (20)

(CHj )3 Sn02 F4 Mn(CO)5 ------* (CHj^SnF + CO +

^ C F 2 xCF \ ( C 0 \ M n ^Mn ( C O ) * (21) N ,CF2 CF,

Alkylmetal compounds have also been found to add to acetylenes. Several cyclopentadienyl(alkyl)metal carbonyl derivatives have been reacted with acetylenes and, in some cases, insertion reactions may -have been involved. (3 3 ) The mechanism of cyclization in the following reaction has not been studied. Allylic halides react catalytically with nickel tetra- carhonyl in alcohol in the presence of acetylene and CO to form esters of cis-2,5-hexadienoic acid. (34) Heck has proposed (1 ) that the intermediate in this reaction may be a n-allylnickel carbonyl halide which undergoes acetylene insertion followed by a carbon monoxide insertion.

Ci^CHCHjjCl + 111000)^7=^0^ aCHCHgNiCOO)2 Cl + 2 CO (23)

-CO „ CD CHg =CHC% Ni(C0)2 Cl (24)

^/CH=CH2 H /GH2- i .CO Ni CO 'C Ni (26) % / ^ 01

H H 0

C00R (27)

6 + HC1 + Ni(C0\ Addition of complexes with metal-metal bonds to acetylenes is not common. Perhaps the most classic ex ample is the addition of dicobalt octacarbonyl to acety lenes. (55) Although the metal-metal bond is not broken, the acetylene is eventually bonded to both cobalt atoms, as shown in an X-ray crystal study by Sly. (56)

— Co(CO)3 (28) C 'CgK; + 2 CO

Recently, the first example of a true carbene insertion reaction with a metal complex was reported by Landgrebe and Mathis. (57) Dichlorocarbene was added to diisopropyl- mercury to give 1 ,l-dichloro-2 -methyl-l-propyl(isopropyl)- mercury.

Cl [(OH, )2 CH] 8 Hg + :CC12 --- ) (CHj )2 CH-C-HgCHCCHj )2 (29) Al

A similar "carbenoid" reaction with stannous chloride was demonstrated by Bonati and Wilkinson. (58) Carbonylcyclo- pentadienyl dimers of iron, molybdenum, and tungsten, when refluxed with tin(II) chloride in tetrahydrofuran for three

days, actually insert :SnCl2 between the two metal atoms. 16 Cl + :SnCl2 — > k-C5 Hj M(CO)-Sn-M(CO) f 7t-C5 fh ) 7C-C5H5M(CO)x]2 X | a When M=Fe x=2 0 1 (30) M=Mo ,W x=3

The examples just discussed verify that the so-called insertion reaction is at once a very general and a very important reaction in transition metal chemistry. Certain ly, it extends the possibilities of developing new syntheses of organic and organometallic compounds. The number of unsaturated molecules which undergo addition with metal complexes indicates that there are probably many other compounds which are capable of the same sort of reaction. For example, the molecules carbon monoxide and sulfur di oxide appear quite similar, both structurally and in the compounds they form. (Figure 1 shows this similarity pictorially.) It therefore seemed reasonable to expect that sulfur dioxide could exhibit a behavior analogous to that of carbon monoxide in forming alkylsulfonyl metal complexes. (See Fig. 1) Supporting this theory is the knowledge that several stable compounds containing a metal-sulfur dioxide moiety have already been reported. As early as 1870, Otto (39) reacted diphenylmercury with gaseous S02 . In benzene solution there was no reaction, but if sulfur dioxide was bubbled through molten diphenylmercury, a reaction took place. The product was not a typical sulfinate although analyses revealed that it contained two sulfur dioxides per each mercury.

C6HgHgC6Hg + 2 S02 — ■■) (Cg Hj S02 )2 Hg (31).

A later attempt to synthesize this compound from benzenesulfinic acid and mercuric chloride was not successful, however. (40) Sulfur dioxide was evolved leaving phenylmercuric chloride as the only mercury compound.

Cg Hg S02 H + HgClg ------> CgHgHgCl + S02 + HC1 (3 2 )

Tetraethyllead and tetraethyltin undergo reactions with sulfur dioxide although the products have not been studied to determine just how the S02 moiety is bonded.

Erankland and Lawrence (41) reacted tetraethyltin with gaseous S02 in the presence of oxidizing agents and re covered two main products: a crystalline substance and an oil. Elemental analyses showed the former to be S02 [sn( C2 Hg ) 3 o] 2 . The oil had the composition S02 C2Hg- [sn(C2 Hj )3 o] and when reacted with sulfuric acid it decom posed to the crystalline product.

Sn(C2 \ + S02 ..X03 > S02 |jSn(C2 Hg )3 o]2 + S02 C2 Hg [sn(C2 Hg )3 o] crystalline oil (33)

2 S02 C2 Hg [Sn(02 Hg )3 o] 0|> > S02 [ Sn(C2 Hg )3 o] 2 + 2 S02 C2 Hg HO (3 4 )

The investigators were never able to elucidate the nature 18

:0«-S = 6: :6 = S-*0: • • • •

0 0 II I R-C-CI R-S-CI I 0 acyl chloride sulfonyl chloride

0 0 II I R-C-R R-S-R I 0

ketone suit one

0 0 II I M-C-R M-S-R I 0

acyl metal sulfonyl metal complex compl ex

Similarity >f Carbon Monoxide , Sulfur Dioxide, and Their Compounds.

Figure I. 19 of these products further, except to report that they did not behave chemically as sulfinates or sulfonates. Tetra ethyllead proved to he less of a problem when reacted with

S02 (42), forming diethylsulfone and plumbic ethylsulfinate.

Pb(C2 Hj )4 + 3 S02 ------+ C* H, 0 PbSa 0* + PbS03 plumbic nrN ethylsulfinate

Magnesium sulfinates are easily prepared by the action

of sulfur dioxide on Grignard reagents. (4-3, 44) The S02 is merely condensed on an appropriate Grignard reagent at -50°G. Hydrolysis of the mixture gives a magnesium sulfinate dihydrate.

BMgBr + 2 S02 g* f^cT^ (RS02 )2 Mg*2 Eg 0 (36)

Triethylaluminum etherate also reacts with liquid sulfur dioxide forming aluminum ethylsulfinate. (45)

AlCCgH,^ •(C2 H5 )20 + 5 S02 — A1(S02 C2 B5 )3 + (C2 H, )2 0 (?7)

It was not until 1938» however, that a concrete ex ample of a covalent metal-sulfur dioxide complex was re ported. Gleu, Breuel, and Rehm (46) found that the color

less hydrosulfito complex of ruthenium tetrammine, jjRu(NB5 \ - (SO, H)2] , exhibited surprising behavior in warm dilute acid, forming red-brown complexes and evolving sulfur dioxide. Even after heating the acidic solution for a long time only one mole of S02 was given off. The other sulfur dioxide molecule remained bound to the metal in diamagnetic com pounds of the tetrammine series of divalent ruthenium. Apparently, coordinated sulfur dioxide is not very labile. Substitution reactions with the new complexes only succeed in replacing the halogens. (46)

Ru(HHj )k (S03 H )2 + 2 HC 1 ---- > [ru(NH3 )4 (S02 )Cl] Cl + S02 + H20 (38)

RuCNH, )* (S02 )Cl| Cl + Ha 0 [RuCNHj )* (S02 ) (Hg O^C^ (39)

When the tetrammine derivatives were reacted with aqueous ammonia in attempts to prepare the pentammine- sulfur dioxide series of complexes, a sulfito compound resulted. (47) But, if this sulfito derivative is acidi fied with warm mineral acids, the desired sulfur* dioxide complex is obtained. (47) To date, the chloride, bromide, nitrate, sulfate, and dithionate derivatives have been prepared. 21 The argument for stable sulfur dioxide complexes of metals was strengthened by the recent preparation of an iron carbonyl-sulfur dioxide derivative by Braye and Hubei. (48) They irradiated iron nonacarbonyl in the presence of sulfur dioxide using ultraviolet light. The result was the evolution of one mole of carbon monoxide and the formation of a dinuclear iron carbonyl species. The sulfur dioxide is believed to bridge both iron atoms through the sulfur.

Fe2 (C0)9 + S02 — — -- > (CO)j, Fe-— — Fe(CO)i, (42) + Fe(CO)9

The same experimenters also irradiated 1,1-tricarbonyl-2 ,5 -dimethoxyferrocyclopentadiene-K-irontricarbonyl with sulfur dioxide. Substitution of S02 for one carbon monoxide took place on the rc-bonded Fe(CO)3 group. (48)

OGH,

Fe(CC )3 + S02 Fe(OO) OCH,

Using essentially the same technique, Strohmeier and Gutenberger (49) irradiated a benzene solution of cyclopentadienylmanganese tricarbonyl and sulfur dioxide with ultraviolet light. Again, carbon monoxide was evolved 22 and a stable sulfur dioxide complex resulted.

Mn + SO, / I

The most recent synthesis of a sulfur dioxide complex of this type was reported by Vaska. (50) Gaseous sulfur dioxide, when bubbled through a solution of chlorobis(triphenylphosphine)carbonyliridium(I), adds in an axial position to form the S02 derivative.

Physical studies of the covalent complexes of sulfur dioxide give insight into the nature of the bonding of the

S02 group. In the case of chlorotetrammine(sulfur dioxide)- ruthenium(II) chloride, crystallographic data prove that

the bonding is through the sulfur. (5 1 ) The structure of the compound is that of a slightly distorted octadedron with the four ammine groups in equatorial positions and

chloride ion and S02 trans to each other in the axial positions. The Ru-S bond distance is slightly shorter O (2.072 A) than transition metal-sulfur bond distances in 23 complexes with, other sulfur-containing ligands. (5 1 ) Ihers (52) noted a surprisingly small M-S hond length in his crystal study of the iridium complex (See Equation 45).

The S02 molecule is bonded through the sulfur in this compound also.1 The short bond lengths in these complexes suggest that there may be some m-bonding between the metal

and S02 . If this is the case, there should also be a lowering of bond order in the sulfur-to-oxygen bonds. This lower ing of bond order would be reflected in a shift of the S-0 stretching frequencies to lower values in the infrared. Table 1 gives reported values of the S-0 infrared stretch ing frequencies for sulfur dioxide-metal complexes and free

S02 . The wave numbers for coordinated sulfur dioxide are all lower than those for the free ligand so it is very likely that there is some -re-character in the M-S bond. It is suggested that the overlap of empty antibonding orbitals

on S02 and filled nonbonding d orbitals on the metal could account for the raising of the M-S bond order and corres ponding lowering of the S-0 bond order. (51) Molecular orbital calculations for these compounds are not available at present, however. The small amount of data which is available concerning

1 It is Of interest to note that iridium, sulfur, and the two oxygens are not planar here. (See Equation 4-5). 24

TABLE 1

Infrared Frequencies (in cm.”'1")

of Free and Coordinated S02

Stretching Frequencies Complex Sym. Asym. Bend

[Ru(NH3 \ (so2 )ci]cia 1 1 0 0 s 1301- 552 m 1 2 7 8 s

|Ru(BH3 )h (S02 )Br]Bra 1 1 0 0 s 1299- 550 m 1 2 7 8 s [RuCNBj )5 S02] Cl2 a 1 0 9 8 s 1303- 548 m 1255 s [Hu( NH5 )5 S02] Br2 a 1117 s 1327- 548 m 1 3 0 1 s b |Fe(CO\] 2 S02 a 1048 s 1209 s b ti:~C5 Hj Mn(CO)a S02 c 1282 s 1333 s S02 (solid)d 114? m 1330- 5 2 1 m 1 3 0 8 s

a - in KBr b - not reported c - in benzene solution See reference (49) d - See reference (53)

Abbreviations s - strong m - medium 2 5 sulfur dioxide complexes has been used to estimate the relative rt-bonding ability of S02 . In the compounds which contain both carbon monoxide and sulfur dioxide (tc-C5 Hj -

Mn(C0)2 S02 , Fe2 (C0)8 S02 , etc.), the carbonyl stretching frequencies are slightly higher in comparison with those

of the corresponding carbonyl compounds (71-C5 H5 Mn(00)3 ,

Fe2 (C0)9 , etc.)* Although there is some difference of

opinion (50), this should indicate that S02 is at least as good a m-bonder as CO, and perhaps somewhat better. Thus, sulfur dioxide appears to be a good ligand in inorganic systems. Recalling (Fig. 1) that, in the reactions which it undergoes and the compounds which it forms, sul fur dioxide bears a striking similarity to carbon monoxide, it is of interest to see how far this analogy can be ex tended. For example, the question arises whether alkyl- or arylsulfonyl derivatives of metal complexes can be synthesized. If they can be, several points of interest may be investigated. First, the route of synthesis is of interest. Acyl derivatives, as already noted, are easily prepared by CO insertion between a metal-alkyl (or -aryl) bond. By analogy, sulfonyl derivatives should be readily formed by

S02 insertion.

M-R + S02 ----- > M-S02-R ' (46) 26 However, reaction of an alkylmetal carbonyl could conceiv ably lead to formation of either an alkylsulfonylmetal carbonyl or a sulfur dioxide-acylmetal complex.

:r -S02-r ^ so2 + S02 --- > M or M (47) "CO '""CO X C-R 0

Second, since acylmetal complexes undergo decarbonylation either upon heating or when exposed to ultraviolet light, sulfonyl derivatives may react in a similar manner, losing S02 .

M-S02-R 0 jrf|—> + soz (^8 )

Another product is also possible under these conditions. The R group could migrate onto the metal resulting in the formation of a sulfur dioxide complex.

^ s o 2 I-SOj-R ore~V3 ~* M v (49) R

A third possibility exists if carbon monoxide is also co ordinated to the metal. The R group could then migrate onto an adjacent CO forming a sulfur dioxide-acylmetal derivative. 27

S02 CO / / or M or M (50) \ \ R R

Finally, some other chemical reactions of sulfonyl complexes could he investigated. For example, it may he possible to selectively reduce the sulfonyl to a sulfoxide or sulfide derivative. This thesis describes the first reported attempt to synthesize sulfonyl derivatives of some low oxidation state transition metals (5^) sund. mercury, a more representative metal. The first examples of sulfur dioxide insertion into a metal-to-carbon bond are discussed and the mode of bonding in the M-S02R moiety of the products is examined. EXPERIMENTAL

Starting materials

Metal carbonyls. The metal carbonyls used in this work were obtained from various sources. Molybdenum hexacarbonyl was donated by the Climax Molybdenum Co.

Iron pentacarbonyl was purchased from Antara Chemicals.

These were used without further purification. Dimanganese

decacarbonyl was obtained as a gift from Prof. H.B. Gray

of Columbia University and was purified by vacuum sub

limation (0.01 mm.; 50°C.) before use.

Cyclopentadienyliron dicarbonyl dimer, jjit-C5 H5 Fe(C0)2] 2 , was prepared as described by Hallam, et al. (55) A mix

ture of excess dicyclopentadiene (210 g.) and iron penta carbonyl (45 g.; 0.25 mole) was heated with stirring in

an oil bath. Extreme care was taken to flush the apparatus

(See Pig. 2) with nitrogen before heating. When the

temperature of the oil bath had reached 100°C. the nitrogen

was turned off and the positive pressure supplied by CO

liberated in the reaction was used to exclude air. The

temperature was then raised to 140-14-5°C. for 12 hours.

If the reaction temperature was allowed to exceed 14-5°C» tarry materials were produced instead of dimer. The mixture was allowed to cool slowly to room temperature over a period

28 Stirring motor

Stirrer Bubbler

—' 5 0 0 ml. Oil 3 -neck flosk bath

Figure 2. Apparatus for the preparation of [ 1T-C5 H5 Fe(CO)2] 2

and [tT -C 5 H5 M o ( C 0 ) 3' ] 2 30 of 12 hours, purple crystals of the dimer forming on cool ing. Further cooling in an ice hath yielded still more product* The crystals were collected on a filter and washed with pentane. No further purification was necessary. Yield: 24.3 g. Additional quantities of

[tc-Cj Hj Fe(C0)2J 2 were purchased from Alfa Inorganics, Inc.

Cyclopentadienylmolybdenum tricarbonyl dimer,

[jt-CsHjMoCCO)^] 2 » was prepared according to the method of Hayter (56) wherein molybdenum hexacarbonyl (100 g.J

0.38 mole) and 200 ml. of dicyclopentadiene were heated together under nitrogen at 140-145°C. Molybdenum hexa carbonyl slowly sublimed out of the reaction mixture and was returned to the reaction vessel (See Fig. 2) by scraping the condenser with a glass rod. After three hours all the Mo(C0)6 was consumed, as shown by the cessation of sublimation, and the reaction mixture was cooled in an ice bath to a temperature of 20°C. Pentane

(200 ml.) was added and the purple crystalline product was collected on a filter. Thorough washing with pentane removed the last traces of dicyclopentadiene. Yield: 79»1 g»

The compound was used without further purification.

Perfluoroalkyl and -aryl derivatives, W-C5 HjMo(C0)3 0F3

and tu-Oj H5 Fe(C0)2 C6 F5 , were graciously donated by Dr. R.B.

King of The Mellon Institute. 31 Other metal complexes. Diphenylmercury, phenylmercuric chloride, and dihenzylmercury were purchased from

Metallomer Laboratories. Diethylmercury was obtained from

Eastman Organic Chemicals and mercuric chloride was pur chased from the J.T. Baker Chemical Co. All mercury com pounds were used as obtained without further purification.

Titanocene dichloride, (x-C5 B5 )2 TiC]^ , was obtained from Arapahoe Chemicals, Inc. and was not purified further before use. Dimethylbis(cyclopentadienyl)titanium was prepared by adding 20 ml. (0.02 mole) of a solution of

CHjLi in diethyl ether to a suspension of 2.59 g. (0.01 mole) of (x-Cj Hj )2 TiCla in 30 ml. of diethyl ether at

-78°C. under nitrogen with stirring. The resulting orange

solution was mixed with 5 g. of neutral alumina and filtered with suction. The addition of alumina seemed to make the

filtration less difficult. The solution was collected and

filtered again by gravity. Ether was removed with a stream

of nitrogen and the orange crystals of (x-C5 H5 )2 Ti(CHj )2 were collected and used immediately due to their unstable nature. This preparation is a slight modification of that

of Piper and Wilkinson. (57) Trans-bis(triphenylphosphine)dimethylpalladium(II) was prepared according to the method of Calvin and Coates.

(58) In the first step ammonium tetrachloropalladate(II),

(NH*)2 PdCl*, was prepared by dissolving 10 g. (0.056 mole) 32 of palladium(II) chloride in an aqueous solution of ammonium chloride (6 g.J 0*11 mole) and evaporating the solution to dryness. Palladium chloride used in these reactions was purchased from Matheson, Coleman, and Bell and was not purified before use. _p In the second step, 10.1 g. (2.84x10 mole) of

(NH«,)2 PdCl* was dissolved in a small amount of cold, freshly boiled water. To this a solution of 14.9 g.

_ o (5.68x10 mole) of triphenylphosphine dissolved in 15 ml. of acetone was added dropwise with stirring. A yellow precipitate of trans-dichlorobis(triphenylphosphine)- palladium(II) formed immediately and was collected on a filter. Recrystallization from absolute ethanol gave pure yellow crystals. -3 Finally, a suspension of 5.3 g. (5x10 mole) of trans- [(C6 % )3 p] 2 PdCl^ in 30 ml. of ether was mixed with

10 ml. (0.017 mole) of LiCHj in ether at -78°C. under nitrogen. The pale brown solution was hydrolyzed at 0°C. with 100 ml. of water and the colorless product, trans-

L(C6H5 ),Pl8 Pd(OB,)2 , was recovered from the ether phase by evaporating the solvent (27°C.j 20 mm.). Recrystall ization from tetrahydrofuran at -78°C. afforded only impure compound. Yield: 0.1 g.

The preparation is stated simply in the following set of equations: 33

2 NH* Cl + PdCl* ----- > (1 ^ ) 2 PdCl^ (51)

(NHj, )2 PdCl* + 2 P(C6 H5 )3 » trans-Pd [p(C6 Hg )3] 2 Cl2 + 2 NH*C1 (52) trana-Pd [P(C6 Hg )J 2 C]* +2 LiCHg -- > trans-Pd [P(C6 Hg )g] 2 - (01% )2 + 2 LiCl (53 )

Ligands, solvents, other reagents, and: chromatography supports.

Anhydrous grade sulfur dioxide, from Matheson, Inc., was dried by passage through concentrated sulfuric acid and a phosphorus(V) oxide-calcium chloride column. (See

Pig. 3) It was then condensed at -40° to -60°C. in a trap immersed in a Dry Ice-isopropanol bath.

Reagent grade chlorine was obtained from Matheson, Inc. and was used without further purification.

Methyl lithium was purchased from Poote Mineral Co. as a 1.6 M solution in diethyl ether,

Other ligands and reagents were purchased from a variety of sources as reagent grade chemicals and were used without further purification. Ethyl iodide, iodobenzene, ethanesulfonyl chloride, methanesulfonyl chlo ride, and methanesulfonyl fluoride were purchased from

Eastman Organic Chemicals. Benzenesulfonyl chloride, benzoyl chloride, acetyl chloride, bromine, ammonium chlo ride, pyridine, and iodine were obtained from J.T. Baker Chemical Co. Matheson, Coleman, and Bell supplied

1 ,3-dibromopropane, the sodium salt of benzenesulfinic acid (NaSOjCgHj), triphenylphosphine, tri-n-butylphosphite, diethyl sulfide, p-toluidine, p-chloroanaline, tetra- methylamTnonium iodide, triphenylphosphite, thiophenol, and sodium borohydride. Methyl iodide was purchased from

Columbia Organic Chemicals Co., Inc., benzyl chloride from

Allied Chemicals, tri-n-butylphosphine from Metal and Thermit

Corporation, and p-toluenesulfinic acid sodium salt di hydrate (NaS02 fyH? *2H2 0) from Aldrich Chemical Co., Inc.

Triphenyltin chloride and chlorotrimethylsilane were donated by Dr. D.W. Meet of The Ohio State University. p-Iodotoluene was a gift of Mr. Bernard Hhem of The Ohio State University.

Tetrahydrofuran (THF) was purified by distillation from LiAlE* under a nitrogen atmosphere immediately before use. Technical grade pentane was used without further purification. All other solvents were of analytical reagent grade and were not purified before use. Spectroscopic grade chloroform and acetone were purchased from Matheson,

Coleman, and Bell. The CDC^ used in HMR studies was obtained from the Volk Chemical Co. in 99*5% isotopic purity.

The alumina which was used as a support for column chromatography was purchased in the neutral form of activity grade I from the M. Woelm-Eschwege Co. and was Glass "^/^WOOl P2 ° 5 CQ Clg

SO-

Dry ice - isopropanol slush - 4 0 ° - 6 0 ° C.

Cone. Liquid S 0 2 h2so4 4- sample

Dewar

Figure 3. Apparatus for drying and condensing S02„ 36 deactivated to grade III for all chromatographic separations.

Elemental analyses and physical measurements

Elemental analyses were carried out by the Galbraith

Laboratories, Inc. or the Alfred Bernhardt Microanalytical

Laboratories of the Max Planck Institute, Mulheim, Germany.

Molecular weight determinations were done by the author and Miss Margaret Jennings using a Mechrolab

Osmometer - Model 301-A. Compounds were dissolved in CHClj _2 to give solutions of concentrations ranging from 1x10 M to 2xlO“^M.

Melting points were measured with a melting-point block and are uncorrected. Infrared spectral studies were carried out on a Beckman

IE-9 spectrophotometer* Solution spectra were taken in a

KBr cell of 0*05 nun. thickness, a matched reference cell being used at all times. Spectra of solid samples were taken as either Nujol mulls or KBr pellets. The Nu^ol was dried over sodium wire.

Proton magnetic resonance spectra was measured by the author, Mr. P.J. Pollick, and Mr. James Walther, using a

Varian Associates A-60 spectrometer with a variable temp erature regulator. The solvents used were CDCI3 , and liquid S02 • Equipment used for ultraviolet irradiations was purchased from the Hanovia Lamp Division of Englehard Hanovia,

Inc. (See Pig. 4). The source of radiant energy was a 450

watt high-pressure quartz mercury-vapor lamp, model 679A-36.

Of the total energy radiated, approximately 30% is in the

ultraviolet portion of the spectrum, 18% in the visible,

and the balance in the infrared. The lamp is operated by

a reactive type transformer, model 34-245-1, which supplies

the extra voltage and current required to initiate the arc

and the reduced power for operation. A double-walled,

water cooled quartz immersion well, model 194-34, holds the

lamp in the center of the reaction vessel. An outlet on the

reaction vessel was connected to a gas burette for measure

ment of the volume of any gas given off during the irradi

ation. The entire system was thermostatted in a constant

temperature water bath.

Preparation of Sulfonyl Derivatives Cyclopentadienyl(phenylsulfonyl)dicarbonyliron(II),

Tt-Cs H; PeCCCOo S0» Cft EU . Cyclopentadienyl(phenyl)dicarbonyl-

iron(II) was prepared using the method of King and Bisnette.

(7) First, it—C5 H5 Fe(C0)2 Na had to be prepared.1 The re action was carried out in a 100 ml. three-neck round bottom

flask fitted with a nitrogen inlet and a mechanical stirrer.

1 This procedure was used without alteration each time tc-C5 Hj Pe(C0)2 Na was needed and therefore will not be described again in future preparations. Water cooled quartz immersion well

Reaction v e s s e l To gas burette

Sample in Lamp C_HL solution '

W a t e r ^ ^ * bath

UV irradiation apparatus Figure 4. 39 The flask had a 1 ml. bulge in the bottom to facilitate removal of amalgam. The complete operation was carried out under a nitrogen atmosphere. A sodium amalgam was prepared by adding 0.45 g. (0.026 mole) of sodium in small portions to 4 ml. (54 g.J 0.37 mole) of mercury.

Local concentrations of solid amalgam were broken up with a glass rod. After the contents of the flask had cooled to room temperature, a solution of 1.77 g. (0.005 mole) of [tc-Cj Hj Fe(C0)2l 2 in 60 ml. of freshly distilled

THF was added and the mixture was stirred for one hour.

During the course of this reduction the initial deep purple solution became reddish-brown, the characteristic color of the product.

2 7t“C5 Hj Fe(C0)2 Na (54) red-brown

Excess amalgam was removed from the flask by means of a hypodermic needle and syringe, the needle being inserted into the bulge at the bottom of the flask. Iodobenzene

(2.04 g.; 0.001 mole) was added to the sodium salt solution and the mixture was stirred under nitrogen for 5 hours at room temperature. Solvent was then removed (30°C.; 20 mm.) leaving a brown residue. This residue was extracted with three 50 ml. portions of pentane and the extracts were treated--with about 10 g. of alumina and filtered. The resulting orange filtrate was concentrated at 20 mm. to 40

a volume of about 5 ml* and chromatographed on an alumina column (5x20 cm.), eluting with pentane. The yellow band

of 7t-C5 H5 Fe(C0)2 CgHg was collected^ J~ju-C5 H5 FeCCO)^] 2 remained on the column. Solvent was removed (2?°C.; 20 mm.)

and the product was used without further purification.

Yield; 0.13 g. One gram (0.004 mole) of tc-C5 Hj Fe(C0)2 C$ H5 was placed

in a trap (20 cm. x 6 cm.) and immersed in a Dry Ice-isopropanol bath at -40°C. Dry S02 was passed into the trap where it condensed. (See Fig. 4) The temperature of the

trap was not crucial except that it had to be between -10°C.,

the temperature at which S02 becomes a liquid, and -78°C. where it freezes. It was found that a temperature of

about -40°C. was easy to achieve and maintain and that the

compounds dissolved readily in liquid S02 at this temp

erature. When all of the tc-C5 Fe(C0)2 C6E^ had dissolved (30-40 ml. was usually sufficient), addition of S02 was discontinued and the excess S02 was removed with a stream of nitrogen as the solution was allowed to warm to room

temperature. There was a slight color change from orange

to red-orange as the iron complex dissolved in S02 , and

when all of the S02 had evaporated a reddish-orange residue remained. This residue was dissolved in about

10 ml. of chloroform and chromatographed on an alumina

column (5x20 cm.). The chromatogram was developed with chloroform* There was some evidence of decomposition to a brown compound which remained at the top of the alumina.

A yellow band of 7E-C5H5 Fe(CO)2 CgHj (0.6 g.) followed by a second yellow band containing 71-O5 H5 Fe(C0)2 802 CgHj appeared. The 7t-C5H5 Fe(C0)2 S02 OgHg was collected and the volume of solution was reduced to about 10 ml. (27°C.; 20 mm.). Then

200 ml. of pentane was added slowly while stirring. Yellow crystals of the sulfonyl derivative formed at once and these were separated from the solution by filtration under nitrogen using suction. After washing the crystals with

20 ml. of pentane no further purification was necessary.

Yield: 36%; 0.46 g.

It should be noted here that the yield can be increased by allowing tc-C5 H5 Fe(C0)2 C61% to remain for a longer time in liquid S02 . For example, if reaction time is increased to two hours the yield is 46% (0.59 g*)« The reaction of X-C5H5 Fe(C0)2 C5H5 with S02 was also carried out in pentane at 27°C. Sulfur dioxide was bubbled slowly through a solution of 1 gram (0.037 mole) of the carbonyl in 50 ml. of pentane. The formation of a yellow precipitate was essentially complete in 48 hours, as evidenced by discoloration of the solution. After this time S02 addition was halted and the pentane was decanted.

The yellow residue was taken up in about 10 ml. of chloro form and the product was purified by chromatography as 42 described above. Yield: 89%; 1.06 g.

Three other methods have been used to prepare tc-C5 H5 Fe(00)2 S02 06 H5 . The first involved a direct reaction between tc-C5 H5 FeCC0)2 Na and benzenesulfonyl chloride. The sodium salt was prepared as described earlier from 1.77 g. (0.005 mole) of Jju-C5 Hj Fe(C0)7| 2 and excess 1% sodium amalgam. When the amalgam had been removed all reactants were transferred to a dry, nitrogen-atmosphere box. The x-C5 H5 Pe(C0)2Na solution was filtered by gravity into a flask containing 1.75 g* (0.01 mole) of pure ClSO^gHj.

The reaction mixture was stirred slowly. Formation of a white precipitate, shown later to be NaCl, was observed and the color of the solution gradually changed from red- brown to red. After all the THF solution of the carbonyl had been added, the reaction flask and contents were re moved from the dry box and the solvent was evaporated

(30°C.; 20 mm.). The residue was extracted with four 10 ml. portions of chloroform, the extracts were combined, and the volume of solution was reduced to about 5 ml. in a stream of nitrogen. The red solution was chromatographed on an a l um ina column (5x20 cm.) eluting with chloroform. Three bands appeared: first a purple band containing 0.2 g. of jjc-C5 % Fe^O)^] 2 , second a red band due to tc-C5 H5 Fe(C0)2 Cl

(0.6 g.), and finally a yellow band of it-Cs Hj Fe(C0)2 S02 CgH5 .

The first two compounds were recovered by removing the 43 solvent (2?°0 .; 20 mm.) and collecting the remaining solid.

The sulfonyl compound was eluted and the volume of the solution waa reduced to about 5 ml. under vacuum (27°C.;

20 mm.). Then 50 ml. of pentane was added with stirring giving 0.07 g. (2 .3%) of pure compound which was filtered and washed with pentane. Anal. Calcd. for O,H, 0 FeO* S:

C, 49.06? H, 3.14; S, 10.05; Fe, 17.65; mol. wt., 318.

Found: C, 49.02; H, 3.19; S, 10.li; Fe, 17.76; mol. wt.,

341.

Benzenesulfonyl chloride was also reacted with jjt-Cj Fe(C0)2] 2 to give a sulfonyl derivative. To a solution of 0.5 g. (1.4 mole) of [m-CjH5 Fe(C0)Q 2 in 10 ml. of freshly distilled THF was added 1.4 mmole (2,48 g.) of

C1S02 C6 H5 . This solution was stirred vigorously under nitrogen for 12 hours. Solvent was then removed (30°C.;

20 mm.) and the red-orange residue was dissolved in 5 ml. of chloroform. Chromatography on an alumina column (5x10 cm.) using CHClj eluent gave a good separation of the two products. First, a red band containing ti-C5 Hj Fe(C0)2 Cl

(0.24 g.; 80.1% yield) was eluted. Then a yellow band

containing tc-C5 Hj Fe(C0)2 S02 Cg H5 was collected and the

solvent was removed under reduced pressure (25°C.; 20 mm.)

giving 0.39 g. (89%) of pure product. This derivative was also prepared from the metathetical

reaction between te-C5 H5 Fe(C0)2 Cl and NaSO^gHj. The tc-Cj H5 Fe(CO)2 Cl was prepared according to the method of

Piper and Wilkinson. (59) In a mixture of 250 ml. of ethanol, 50 ml. of CHC13 , and 7.5 ml* of concentrated

HC1, 3.5 g. (0.01 mole) of Jtc-Cj H5 Pe(C0)2J 2 was dissolved.

Oxygen was bubbled through the mixture for three hours.

The solution was then evaporated to dryness under reduced pressure (40°C.; 20 mm.) and the red residue extracted with 300 ml. of water. Filtration with suction enabled

the separation of the soluble chloride from insoluble

unreacted dimer. The water solution was evaporated to

dryness (50°G.; 20 mm.) and the residue was extracted into about 20 ml. of CHC13 . The product was recrystallized

from chloroform by adding 200 ml. of pentane and chilling

the mixture at 0°C. in an ice bath for 30 minutes. Red

crystals of x-Cj H5 Fe(C0)2 Cl precipitated and were collected

on a filter to give an 84.5% yield (3.6 g.).

One half gram (0.0023 mole) of x-C5H5 Pe(C0)2Cl and 0«38 g. (0.0023 mole) of NaS02 C6H5 were dissolved in 50 ml.

of methanol. The solution was stirred under nitrogen for

12 hours at 27°C. There was some decomposition to a brown

solid which was removed by filtration. Methanol was removed

from the orange solution (60°C.; 20 mm.), the residue was

redissolved in 20 ml. of CHC13 , and the solution was chro

matographed on an alumina column (5x20 cm.). The chromato

gram was developed with chloroform. The first band on the 4-5 column contained unreacted n - C 5 H5 Pe(CO)2 Cl (0.05 g.).

The second, a yellow hand, contained te-C5 Hj Fe(CO)2 S02 • Solvent was evaporated in a stream of nitrogen to give

0.5 g. (73% yield) of pure product. Cyclopentadienyl(methylsulfonyl)dicarbonyliron(II), tc— Hs Fe(CO)«> S09 CSt . Cyclopentadienyl(methyl)dicarbonyliron(II) was prepared according to the method of Piper and Wilkinson (57) wherein tc-C5 H5 Fe(C0)2 Na, prepared from

3.54- g. (0.01 mole) of jjrc-C5 Hj Pe(CO)g] 2 and excess 1% sodium amalgam in 60 ml. of freshly distilled THE, was reacted under nitrogen with 1.02 g. (0.02 mole) of iodo- methane. After stirring the mixture for three hours at room temperature the solvent was removed (27°C.; 20 mm.) and the residue was taken up into 30 ml. of pentane and filtered through 10 g. of alumina. The volume of the filtrate was reduced to about 5 ml. in a stream of nitrogen and the solution was chromatographed on an alumina column

(5x20 cm.). Elution with pentane enabled the yellow methyl

compound to be easily separated from any unreacted dimer.

The purple dimer remained on the column while 7t-C5 H5 Fe-

(CO)2 CH3 was eluted. Solvent was removed in a stream of nitrogen and the remaining solid was purified by subli mation (0.01 mm.; 27°C.) onto a cold finger maintained at

-78°C. with a Dry Ice-isopropanol slush. Yield: 2.69 g.

One gram (0.005 mole) of x-C5 H5 Pe(C0)2 CHj was dissolved in about 40 ml. of liquid S02 at -40°C. The

S02 solution became deep red immediately. As soon as all of the compound had dissolved, addition of S02 was dis continued and the excess S02 was removed with a stream of nitrogen as the solution was allowed to warm to room temp erature. The red residue which remained was dissolved in 10 ml. of chloroform and chromatographed on an alumina column (5x20 cm.) eluting with CHC13 . Only one moving band appeared on the column and it was found to contain tc—C3 Hg Fe(C0)2 S02 CHg . There was some evidence of decom position to a brown compound which remained at the top of the alumina. The solution of te-C5 Hg Pe(C0)2 S02 CHg was con centrated to about 10 ml. (27°C.; 20 mm.) and 200 ml. of pentane was added slowly while stirring. Yellow crystals

of the sulfonyl compound formed at once and were collected

on a filter under nitrogen using suction. After washing

the crystals with 20 ml. of pentane no further purification was necessary. Yield: 95%^ 1*27 g.

The reaction between te-C5 Hg F e(C 0 )2 CHg and S02 was

also carried out in solution. One gram of m-CgHgFe(C0)CEg -

(0.005 mole) was dissolved in 50 ml. of pentane and S02

was bubbled slowly through the solution at 27°0. A yellow

precipitate, slowly formed accompanied by gradual discolor

ation of the pentane solution. When the solution was

essentially colorless (after 12 hours) S02 addition was stopped and pentane was decanted. The yellow residue was taken up in about 10 ml. of chloroform and chromatographed on an alumina column (5x20 cm.) eluting with chloroform.

Only a band due to x-05 Hj Fe(C0)2 S02 CBj appeared. This band was collected and solvent was removed (27°C.; 20 mm.) yielding 1.27 g. of the compound. (95% yield) This derivative was also prepared from the reaction of

7t-C51% Fe(C0)2 Na with C1S02 CBj . As described earlier, k-C5 H5 Fe(C0)2Na was synthesized from 1.77 g. (0.005 mole) of jjn:-C5 Hj Fe(C0)2j[ 2 and excess 1% sodium amalgam in 60 ml. of freshly distilled THF. The solution of x-C5 HjFe(C0)2 Na was filtered with stirring into a flask containing 0.01 mole

(1.15 g») of methanesulfonyl chloride in a dry, nitrogen- atmosphere box. Removal of THF (27°C.J 20 mm.) left a red residue which was taken up in about 20 ml. of chloroform and filtered by suction. The filtration was facilitated by the addition of about 10 g. of alumina to the solution.

Purification was effected by chromatography on an alumina

column (5x20 cm.) eluting with chloroform. The yellow band which contained the product was preceded by a purple band

containing [rc-C5 H5 Fe^O)/} 2 (0.19 g.) and a red band of X-C5H5 Fe(C0)2Cl (0.56 g.). Removal of chloroform with a

stream of nitrogen gave 0.05 g. (2% yield) of pure Tt-rCjI^Fe- (C0 )2S02CH3 , Anal. Calcd. for CgHgFeO^S: C, 37.50* H, 3.12

S, 12.50,* Fe, 21.87? mol. wt. 256. Found: C, 37.36; H, 2.99 48

S, 12.70; Fe, 21.64*, mol. wt. 262.

This same reaction was attempted using 7t-C5 Hj Fe(CO)2 Na and FS02 CBj . The procedure which was used with CISO2 CB3 was also followed here. A THF solution of m-C5 Hj Fe(CO)2 Na

(60 ml.) prepared from 1.77 g. (0.005 mole of [m-CjHjFe- (00 )2] 2 and excess sodium amalgam was added under nitrogen

to 0.98 g. (0.01 mole) of FS02CHj with stirring. Solvent

was then removed (30°C.; 20 mm.) and the residue was washed

with four 10 ml. portions of CHCI3 . The volume of the

resulting red solution was reduced to about 5 ml. (27°C.;

20 mm.) and purification was begun on an alumina column

(5x20 cm.). Elution with chloroform gave two bands on the

column. The first was due to [71-O5 Fe(C0)2J 2 (0.8 g.

recovered by removing the solvent in a stream of nitrogen)

and the second contained tc-C5H5 Fe(C0)2 S02CH3 . When chloro

form was removed (27°C.; 20 mm.) 0.05 g* (2% yield) of the

pure product remained.

A fourth preparation of tu-C5 H5 Fe(C0)2 S02 CHj involved

the reaction of [m-C5 H5 Fe(C0 )2] 2 and methanesulfonyl

chloride. To a solution of 0.5 g. (1.4 mmole) of [m-CjHjFe-

(C0)£J 2 in 10 ml. of freshly distilled THF was added 1.4 mmole (0.16 g.) of CISO2CH3 . The solution was stirred under

nitrogen for 12 hours after which time solvent was removed

(30°C.; 20 cm.) and the red-orange residue was dissolved

in 5 ml. of chloroform. Chromatography on an alumina 4-9 column (5x20 cm.) eluting with. CHCI3 separated the mixture into two hands. The first hand contained x-G, H, Fe(CO)2 Cl

(0.2 g.). A yellow band which followed was eluted and solvent was removed (2?°C.; 20 mm.) yielding 0.32 g.

(90%) of pure 71-C5H5 Fe(C0)2 S02 CH, .

In a similar reaction, 0.5 g. (1*4- mmole) of [x-CjBjFe

(CO)/] 2 and 0.14- g. (1.4- mmole) of FS02 CH, were dissolved

in 10 ml. of freshly distilled THF and the solution was

stirred at room temperature for 12 hours under nitrogen.

Solvent was removed under reduced pressure and the residue was taken up in about 5 ml. of CHCl, . Purification was

effected on an alumina column (5x20 cm.) eluting with

chloroform. A purple hand containing 0.4- g. of the dimer

was eluted first. The only other hand was a yellow one

which contained 0.004- g. (1% yield) of x-C5 H, Fe(C0)2 S02 CH, . Cyclopentadienyl(ethylsulfonyl)dicarbonyliron(II),

Tt-Cc Ek FeCCO), SO, C, Hg . The preparation of x-C5 H, Fe(C0)2 - S02 C2 H, from x-C, H, Fe(G0)2 02 H, and S02 first involved the

synthesis of x-C5 H, Fe(C0)2 C2 H, • This was made following

the method of Piper and Wilkinson (57) wherein x-CjHjFe-

(C0)2Ua was reacted with IC2H5 . Freshly prepared x-CjH^Fe-

(C0)2Wa, made by reacting 5«3 g. (0.015 mole) of [x-C,^-

Fe(CO)^] 2 with excess 1% sodium amalgam in 60 ml. of THF,

was stirred with 3.87 g« (0.03 mole) of ethyl iodide under

nitrogen at 27°C. for two hours. Solvent was removed (27°C.; 20 mm.) and the residue was taken up in 40 ml. of pentane. The pentane solution was filtered through 10 g. of alumina and the volume of the filtrate was reduced to about 5 ml. in a stream of nitrogen. Purification was accomplished on an alumina column (5x20 cm.) eluting with pentane. All unreacted [jc—05 Fe(CO)^] 2 remained on the column while the yellow product was easily removed with pentane. A stream of nitrogen was concentrated on the solution until infrared spectra indicated that all solvent had been removed from the yellow liquid product. When all solvent peaks had vanished from the infrared spectrum the compound was assumed to be pure and no further purification was attempted. Yield: 7.16 g.

Dry sulfur dioxide was condensed at -40°C. over 0.5 g.

(0.24- mole) of x-C5 Fe(C0)2 C2 1% until all of the iron compound dissolved (about 40 ml. of solution). The S02 solution became deep red almost immediately. , Excess S02 was removed with a stream of nitrogen and the residual solid was taken up in about 5 ml. of chloroform and purified by alumina chromatography. The single moving band on the column (5x20 cm.) was eluted with CHGI3 . This band con tained the yellow product in 91% yield (0.6 g.). A brown decomposition compound remained on the top of the alumina.

The product was recovered by reducing the volume of the chloroform solution to about 10 ml. (27°C.j 20 mm.) and 51 adding 150 ml. of pentane with stirring. The pentane in duced immediate precipitation of the pure compound which was collected on a filter under nitrogen.

This derivative was also prepared from the reaction between X-C5H5 Fe(CO)2Na and ClSC^C^Hj. Thus, TC-CjHsFe-

(CO)2Na was prepared as described previously from 1.77 g.

(0.005 mole) of ^c-C5 H5 Fe(CO)^] 2 and excess 1% sodium amalgam in 60 ml. of THF. The red-brown solution of the sodium salt was filtered in a dry, nitrogen-atmosphere box to remove any suspended amalgam. The filtrate was added dropwise with stirring to 1.29 g. (0.01 mole) of C1S02 C2 H5 . Formation of a white precipitate of N a d was observed. The reaction mixture was removed from the dry box and the solvent was evaporated (27°C.; 20 mm.). The residue was extracted with about 10 ml. of CHCI3 • The solution was chromatographed on an alumina column (5x20 cm.)

in the usugl manner, eluting with chloroform. A purple band ( jrc—05 Hj Fe(C0)J 2 ; 0.18 g.) and a red band (x-OjHjFe- (C0)2 Ci; 0.6 g.) preceded the yellow band of the sulfonyl product in the order given. From the eluted solution of

71-C5E5 Fe(C0)2 S02 C2 H5 solvent was evaporated (40°C.‘, 20 mm.)

to yield 0.05 g. (1.9%) of the product. Anal. Calcd.

for C9 H, o FeO* S: C, 40.00*, H, 3.71*, Fe, 20.75. Found: C,

39.94; H, 3.88*, S,'11.6i; Fe, 20.86.

A third method of preparing Tt-C5 % Fe(C0)2 S02 C2 52 utilized the reaction of [7U-C5 H5 Fe(CO)^] 2 with ethanesulfonyl chloride. One half gram of (jt-05 H5 Fe(CO)^j 2 (1.4 mmole) and 0.18 g. (1.4 mmole) of C1S02 C2 H5 were dissolved in 10 ml. of freshly distilled THF. This solution was stirred vigor ously under nitrogen for 12 hours. Solvent was removed

(27°C.; 20 mm.) and the red-orange residue was dissolved in

5 ml. of chloroform. Chromatography on an alumina column

(5x15 cm.) using CHCJ^ eluent gave two products. First, a red band containing tc-Cj H5 Fe(C0)2 Cl (0.18 g.) was eluted. Then a yellow band of it-Cg E5 Fe(C0)2 S02 C2 H5 was collected.

The sulfonyl derivative was recovered by reducing the volume of solution to about 5 ml. in a stream of nitrogen and stirring in 50 ml. of pentane to cause precipitation.

The yellow product was then collected on a filter and washed with pentane. Yield: 0.33 g.J 88%. Cyclopentadienyl (benzyl sulfonyl )dicarbonyliron( II),

Tt-Cg H* Fe(CO), SOo CHo C& EL; . In order to prepare this deriv ative the parent compound, n - 0 5 % Fe(C0)2 CE^ Cg Hj , had to be synthesized. This compound had been hitherto unknown.

Preparation of cyclopentadienyl (benzyl )dicarbonyliron(II) , Ti-Cg Hg Fe(CO). CH» C<; EU . To a solution of the sodium salt of cyclopentadienyliron dicarbonyl, freshly prepared from 1.77 g. (0.005 mole) of [x-C5H5 FeCCO)^ 2 and excess 1% sodium amalgam in 60 ml. of THF, was added

1.27 g. (0.01 mole) of benzyl chloride. The reaction 53 mixture was stirred at room temperature for three hours.

Ihen the solvent was removed (27°0 .? 20 mm.) and the

residue was extracted with four 20 ml. portions of pentane.

The pentane solution was mixed with about 10 g. of alumina

and filtered using suction. The volume of the filtrate

was reduced to 10 ml. with a stream of nitrogen and pur

ification was carried out on an alumina column (5x30 cm.).

Elution with pentane enabled the yellow it-C5 H5 Pe(C0)2 CHg Cg H5 to move down the column while unreacted [te—C5 B5 Fe(C0)2J 2

remained on the column. The yellow band containing the

desired product was collected and the volume of solution

reduced to about 5 ml* in a stream of nitrogen. This

solution was placed in Dry Ice for about 15 minutes,

: during which time crystals of the benzyl compound formed.

The yellow-brown crystals were collected on a filter and

washed with cold pentane. No further purification was

needed although the compound can be sublimed (50°G.?

0.01 mm.). Yield: 1.5 g.? 56.5%. Anal. Calcd. for

C ^ H ^ F e O a t C, 62.70; H, 4.49; Fe, 20.90*, mol. wt. 268.

Found: C, 62.73? H, 4.68? Fe, 21.09? mol. wt. 242?

m.p. 55-57®C.

One gram (0.003 mole) of tc-C5 H5 Fe(C0)2 CHa Og was dissolved in 40 ml. of liquid S02 and allowed, to react

for two hours at —40°C. At the end of this time, S02 was

removed from the orange-red solution with a stream of 54 nitrogen. The remaining solid was dissolved in a minimum of chloroform (about 5 ml.) and chromatographed on an alumina column (5x20 cm.). The chromatogram was developed with chloroform giving two yellow bands. The first con tained unreacted tc-Cj 1% Fe(CO)2 CHg C6 Hj (0.5 &•) and the second tu-C5 Hj Fe(C0)2 S02 CHg Cg H5 . There was some decompo sition to a brown compound which could not be eluted off the column. The band containing the sulfonyl product was collected and the volume of solution was reduced to about

10 ml. (27°C.J 20 mm.). Then 200 ml. of pentane was added slowly with stirring. Yellow crystals formed at once and were collected on a filter under nitrogen using suction.

After washing the crystals with 30 ml. of pentane no fur ther purification was necessary. Yield: 40%; 0.31 g.

It should be noted that the yield of tc-C5 Fe(C0)2 -

S02 CHg C6 Hj can be increased by allowing the starting material to remain for a longer time in liquid sulfur di oxide. For example, if reaction time is increased to two hours the yield is increased to 64% (0.50 g.).

CyclopentadienyK p-tolylsulfonyl)dicarbonyliron(II), tc-Cr Hg FeCCOla (p-SOo Ca EL OH* ). Before this derivative could be prepared it was necessary to make the parent compound, tc-C5 H5 Fe(C0)2 (£—tolyl), which had never been prepared before.

Preparation of cyclopentadienylfp-telyDdicarbonyl-

iron( II) , x-Cq S; Fe (CO )■> ( p-1olyl). A solution of n-C5 H5 Fe- (CO)2Na was prepared in 60 ml. of freshly distilled THF from 7.08 g. (0.02 mole) of cyclopentadienyliron dicarbonyl dimer and excess 1% sodium amalgam. When the amalgam had been removed, 8.72 g. (0.04 mole) of £-iodotoluene was added to the sodium salt under nitrogen. This mixture was refluxed at about 65°C. for twelve hours. At the end of this time solvent was removed from the solution (20 mm.;

27°C.). The residual solid was washed with four 20 ml. portions of pentane and the washings were filtered through

20 g. of alumina. Reduction of the volume of the deep red filtrate to about 5 ml. (27°C.; 20 mm.) was followed by chromatography on an alumina column (5x40 cm.). The chroma togram was developed with pentane since the yellow product, tu-C5 H5 Fe(C0)2 (£-tolyl), was easily eluted with this solvent while unreacted dimer remained on the alumina. The compound was recovered by removing all pentane from the eluted solution with a stream of nitrogen and subliming the yellow oil which remained (50°C.; 0.01 mm.). The sub limate was captured on a cold finger which was cooled to

-78°0. with a Dry Ice-isopropanol slush. Yellow crystals collected on the cold finger but pressure exerted by the spatula in attempting to scrape the crystals from the cold finger caused the compound to revert to an oil. This oil was collected but the yield was so small (0.04 g.; 0.37% yield) that elemental analyses were not attempted. Freshly chromatographed x-C5 H5 Fe(CO)2 (£-tolyl) (0.02 g.

7 .3x10 mole) was dissolved in 5 ml. of pentane to facil itate transfer to a trap (20 cm. x 6 cm.). Dry sulfur dioxide was passed into the trap (-40°C.) where it condensed to give about 10 ml. of liquid S02 . Two layers formed with the more dense S02 comprising the lower layer. A colorless S02 layer changed to orange and a corresponding loss of color in the pentane layer indicated that the carbonyl compound was being extracted into the sulfur dioxide. When the pentane had become colorless (usually after 2 or 3 minutes), addition of S02 was discontinued and the system was allowed to stand at -40°C. for 2.4 hours. (Immediate removal of S02 yielded no sulfonyl product.) At the end of this time pentane and S02 were removed with a stream of nitrogen as the mixture was allowed to warm to room tempera ture. The orange residue was dissolved in 5 ml. of CHC13 •

Purification by chromatography gave two products. There was no evidence of decomposition. The first band on the column contained about 0.015 S« of the parent carbonyl.

The second yellow band yielded only trace amounts (0.005 S«) of 7u-05 B5 Fe(CO)^ (£-S02 Cg CE3 ) when the solvent was removed

(27°C.; 20 mm.). The compound was identified by its infra red spectrum. The formation of x-05 Hj Fe(C0)2 (£-S02 C6 B* CHj ) , however, indicated that the starting compound which has not been analyzed was, indeed, x-05 H5 Fe(C0)2 (£-tolyl). This derivative was more successfully prepared by the metathetical reaction between n - C 5 H5 Fe(CO)201 and NaS02 -

(j>-tolyl) *2 Hg 0. A methanol solution (50 ml.) of 0.50 g.

(0.025 mole) of it-Cg Fe(C0)2 Cl, which was prepared as de scribed earlier (page 44), and 0.47 g. (0.023 mole) of

NaS02 (|>=tolyl) *2 0 was stirred at 27°C. for 12 hours under nitrogen. There was some decomposition to a brown solid which was removed by filtration. The remaining orange solution was evaporated to dryness (30°C.; 20 mm.) and the residue was redissolved in about 5 ml. of chloro form. The solution was chromatographed on an alumina column (5x15 cm.). The chromatogram was developed with chloroform. A red band containing less than 0.05 g. of unreacted tc-C5 H5 Fe(C0)2 Cl was followed by a yellow band of tc-Cj % Fe(C0)2 (£-S02 CgHj CH, ). The yellow band was eluted and the volume of solution was reduced to about 5 ml. with nitrogen. Pentane (150 ml.) was added with stirring. A fluffy yellow precipitate formed at once and was collected on a filter under nitrogen with suction. After washing the product with 20 ml. of pentane no further purification was necessary. Yield: 0.69 g.J 90%.

(Sulfonyltrimethylene)bis(dicarbonylcyclopentadienyl- iron(II)) and (trimethylenedisulfonyl)bis(dicarbonyl- cyclopentadienyliron(II)), u-0c He Fe(C0)» S0» (CH» )« Fe(C0)» -

N-O: E; ) and 7i-Cg H* FefCO), SO, (CH, )* SO, Fe(CO). (n-C* E, ). The 58 parent compound for these sulfonyl derivatives, [tc-C5 H5 Pe-

(CO)£j 2 (CHg)3 , was prepared using a modification of the procedure of King. (60) A solution of x-C5 Hj Pe(CO)2 Na, prepared from 3.54 g. (0.01 mole) of [tc-Cj Fe(CO)2] 2 and excess 1% sodium amalgam in 60 ml. of freshly distilled THF, was treated with 4.04 g. (0.02 mole) of 1 ,3-dibromopropane.

The mixture was stirred for three hours at 27°C. under nitrogen. Solvent was then removed from the reaction mix

ture at 20 mm. (27°C.) leaving a brown residue. This residue was extracted with four 20 ml. portions of pentane and the

extracts were treated with 10 g. of alumina and filtered.

The resulting orange filtrate was concentrated at 20 mm.

(27°C.) to about 15 ml. As the volume of the solution de

creased, orange crystals of the product formed. Cooling

the solution to -78°C. in Dry Ice facilitated formation of

the crystals which were collected on a filter and washed

with 20 ml. of cold pentane to give pure [x-C5 H5 Pe( C0)2] 2-

(CHg )3 . Yield: 3-7 g. One gram (0.0024 mole) of [x-C5 Hj Fe(C0)^j 2 )3 was

dissolved in 90 ml. of liquid sulfur dioxide and allowed

to stand for 12 hours at about -40°C. Then S02 was removed

with a stream of nitrogen as the solution warmed to room

temperature and the red-orange residue was taken up into

about 20 ml. of chloroform. Purification was effected on

an alumina column (5x30 cm.) using CHC13 eluent. Pour bands appeared on the column. Tbe first, a purple band, contained trace amounts (less than 0.005 g.) of [x-C^HjFe- (C0)2] 2 . Tbe second, a yellow band, contained about 0.06 g. of tbe parent propylene complex. Tbe tbird was due to a pale yellow "insertion" product, n - G 5 % Fe(C0)2 S02 (CH2 )3 - Fe(C0)2 (n-Cj H5 ). Finally, a very slow-moving yellow-orange band was eluted and was found to contain a second "insertion" product, x-C5 H5 Fe(C0)2 S02 (CI^ )3 S02 Fe(C0)2 (7t-C5 E5 ). Botb tbe sulfonyl compounds were isolated by evaporation of tbe

solvent (30°C.? 20 mm.) and recovery of tbe solid under nitrogen witb no further purification. Attempts to recrys-

tallize tbese derivatives from cbloroform-pentane resulted

in sticky products. Tbe compounds bave a tendency to be

come gummy under pressure and after exposure to moist air.

Yields: for Qn:-C5 H5 FeCCO)^ ^ O ^ C H ^ ; 18.6%, 0.2 g.*, for

[rt-Cj H5 Fe(C0)£] 2 (802)2 (0112)5 ; 61.5%, 0.8 g. Tbe yield of Tt-C5 H5 Fe(C0)2 S02 (CH^ )3 S02 Fe(C0)2 (tt-C5 H5 ) can be increased by prolonging tbe reaction time in liquid

S02 , since tbis "di-insertion" product can be made by dissolving tbe "mono-insertion" compound, 7t-C5 H5 Fe(C0)2 S02-

(CH2 )3 Fe(CO)2 (x-CjI^ ), in liquid S02 . Correspondingly,

increased reaction time decreases tbe yield of tbe "mono

insertion" product,

Cyclopentadienyl(metbylsulfonyl)trie arbonylmolyb-

denum(II), u-C« K; Mo (CO), SO, CH, . Pure tc-C5 %M o ( C 0 )5 CHj was 60 prepared according to the method of Piper and Wilkinson.

(57) The sodium salt of molybdenumtricarbonyl was prer pared following the procedure used in the synthesis of tu-C5 Pe(C0)2 Na (page 39). A 1% sodium amalgam was pre pared under nitrogen by adding 0.4-5 g. (0.026 mole) of sodium in small portions to 4- ml. (54- g.^ 0.37 mole) of mercury. Local concentrations of solid amalgam were broken up with a glass rod. When the contents of the flask had cooled to room temperature, a solution of 11.3 g.

(0.025 mole) of [tc-CjH5Mo(C0 )3J 2 in 60 ml. of freshly dis tilled THF was added and the mixture was stirred for one hour. As the reaction progressed the purple color of the dimer faded to a pale yellow, the color of the sodium salt.

Excess amalgam was removed from the flask with a hypodermic

[k-C^Mo(C0)3] 2 + 2 Ha — 2 it-O, % Mo(CO)3 Na (55) purple yellow needle and syringe and the sodium salt was then ready for reaction.

Methyl iodide (1.4-2 g.; 0.01 mole) was added to this

solution of te-Oj H5 Mo(C0)3 Na and the mixture was stirred vigorously under nitrogen at 27°C. for one hour. Solvent was then removed (27 °C.; 20 mm.) and the residue was collected. Pure tu-C5 H5 Mo(C0)3 CE^ was recovered from the

residue by vacuum sublimation (50°C.J 0.01 mm.) onto a cold 61 finger which, was maintained at -78°C. with a Dry-Ice- isopropanol slush. Yield: 2.21 g.

One gram of tc-C5 HgMo(C0)3 CBj (0.004 mole) was placed in a 20x6 cm. trap at -40°C. Dry S02 was passed into the trap where it condensed, dissolving the carbonyl (about

40 ml. of S02 was sufficient). There was some decompo sition to a black solid. As soon as all of the carbonyl had dissolved the excess sulfur dioxide was evaporated under nitrogen as the solution warmed to room temperature. The residue was treated with 10 ml. of chloroform and the ex tracts were filtered by gravity to remove the insoluble black solid which gave no bands- in the infrared and was pre sumed to be molybdenum metal. (0.005 g. of this solid was recovered) The volume of the filtrate was reduced to 5 ml. in a stream of nitrogen and purification by chromatography on an alumina column (5x15 cm.) was begun, eluting with chloroform. One yellow-green band appeared on the column.

It was collected and the solution was concentrated (27°C.^

20 mm.) to a volume of about 5 ml. Pentane was added in three 50 ml. portions with stirring, causing the precipi tation of 1.02 g. (83% yield) of pure, golden Tt-CjI^Mo- (C0)3 S02 CHj .

Attempts to prepare this derivative in the same manner as its iron counterpart were not successful. A solution of

1 g. (0.002 mole) of [tc-Cj Mo(CO)^] 2 and 0.23 g. (0.002 62 mole) of CISOgCHj in 50 ml. of THF was stirred under nitro gen for 24 Hours at 27°C. At the end of this time solvent was removed (27°C.J 20 mm.) and the residue was taken up in

10 ml. of CHClj and chromatographed on an alumina column

(5x20 cm.) eluting with chloroform. Only one purple band appeared and this was collected. The solvent was removed

(27°C.J 20 mm.) and the residue was collected without fur ther purification (0.97 g.). A comparison of infrared

spectra showed the solid to be [7t-C5 B5 Mo(CO)^] 2 . There was no decomposition.

Also, the reaction between tc-C5 H5 Mo(C0)3 Na and each C1S02 OB3 and FS02 CHj was attempted. The m-C5 Hj Mo(C0)3 Na was prepared from 4.90 g. (0.01 mole) of [tc-C5 H5130(00 )5] 2 and excess 1% sodium amalgam which were stirred in 60 ml.

of freshly distilled THF for 5 hours at 27°C. under nitrogen.

The solution of the sodium salt was transferred to a dry, nitrogen-atmosphere box and filtered by gravity into a flask

containing 2.30 g. (0.02 mole) of C1S02CHj . Occasional

stirring was sufficient to mix the reactants. When all of

the sodium salt had been added the now orange solution was

removed from the dry box and solvent was removed under re

duced pressure (30°C.; 20 mm.). Chromatography on an alum

ina column (5x20 cm.), eluting with CHC13 , gave one orange

band which was collected and the solution was evaporated

(27°C.; 20 mm.). The orange product was found to be 63 7t-C5 H5 Mo(CO)3 Cl, m. pt. 114°C. (dec.) Yield: 3.0 g.J

92.5%. Anal, calcd. for CgHgClMoOj: C, 34.10*, H, 1.78.

Pound: C, 34.17*, H, 1.86.

When x-C5 H5 Mo(C0)3 Na, prepared as described above from

2.45 g. (0.005 mole) of [rt-Cj H5Mo(C0 )^j 2 and excess sodium amalgam in 60 ml. of THF, was added dropwise with stirring to 0.98 g. (0.01 mole) of FS02CHj in a nitrogen atmosphere there was no formation of an orange solution. Instead, a purple product accompanied by considerable bubbling and decomposition to a brown-black solid, which gave no 0-0 peaks in the infrared, resulted. The dark solid was re moved by filtration (0.5 g. yield) and the purple filtrate was evaporated (30°C.; 20 mm.) to give 1.5 g. of (7C-C5 H5 M0-

(CO)jJ 2 • dimer was identified by its infrared spectrum.

Preparation of the sulfonyl derivative was possible using the hydride of cyclopentadienylmolybdenum tricarbonyl

and me thane sulfonyl chloride. The method of Piper and

Wilkinson (57) was used to make 7t-C5 B5 Mo(CO)3 H. To the

dry sodium salt, prepared as described above from 2.45 g.

(0.005 mole) of [rc-C5H5Mo(C0 )£| 2 and excess 1% sodium amal

gam in 60 ml. of freshly distilled THF, was added a stoi

chiometric amount (0.5 g.» 0.01 mole) of glacial acetic

acid. The mixture was stirred for 15 minutes and solvent

was removed under reduced pressure (27®0.J 20 mm.). The

product was sublimed (0.01 mm .\ 50°C.) from the residue TABHE 2

3. Analyses for Iron and Molybdenum Sulfonyl Derivatives

Compound______Calculated C H S M 0 C HSM 0

C5H5Fe(C0 )2 S02 CH3 37.50 3.12 12.50 21.87 25.00 37.80 2.99 12.76 21.80 23.94

C5H5Fe(C0)2S02C2H5 40.00 3.71 II .85 20.75 23.71 40 .16 3.83 11.68 21.12 23.62

CsHsFe(C0)2S0sC6H5 49.06 3.14 10.05 17.65 49.15 3.25 9.86 17.29

C5H5Fe(C0)2S02CH2C6H5 50.60 3.62 9.65 16.87 50.47 3.85 9.35 16.90

C^HgFe(C0)2(£-C6H4 CH3) 50.60 3.62 9.65 50.40 3.48 9.80 jc5H5Fe (C0 )2] 2S02v(CH2 )3 44.55 3.48 6.96 24.35 44.25 3.34 6 .7 4 24.69

[C5H5Fe(C0)2j2(S02)2(CH2)3 58.93 3.06 12.21 21.38 38.72 3.12 13.05 21.64

C5H5Mo(C0)3S02CH3 33.30 2.47 9 .8 8 29.60 33-21 2.69 9-57 29.42

Prepared ty insertion of S02

cn 65 onto a probe cooled to 0°C. The yellow hydride was then ready for use.

One gram of m-Cs H5 Mo(CO)3 H (0.004- mole) and 0.4-6 g.

(0.004- mole) of CISOgCHj were dissolved in 30 ml. of THF

and stirred under nitrogen at 27°C. for 30 minutes. The volume of solvent was then reduced to about 5 ml. in a

stream of nitrogen and purification was begun. Chroma

tography on an alumina column (2.5x10 cm.) using CHC13

eluent gave three bands. The first was a purple band due

to [tc-CjHjMoCCO^J 2 (0.01 g.), and the second band con tained orange it-C5 H5Mo(CO)3 Cl (0.90 g.}. The third band contained a trace amount of tc-C5 H5 Mo(C0)3 S02 CHj (0.01 g.J

1% yield). This band was eluted and the volume of solution

was reduced to about 3 ml. in a stream of nitrogen. Fifty

milliliters of pentane were stirred into the solution

giving immediate precipitation of the golden product, which

was collected on a filter under nitrogen.

Phenyl (phenyl sulfonyl )mercury (II), Ct Hg HgSO? Ct K; .

Five grams of pure diphenylmercury (0.014- mole) were placed

in a 20x6 cm. trap at -4-0°C. Dry sulfur dioxide was passed

into the trap where it condensed. When all of the mercury

complex had dissolved (usually 50-60 ml. of liquid S02 was

necessary) addition of S02 was discontinued and the solution

was allowed to shand for 4-8 hours at -40 °C. A stream of

nitrogen was then passed through the trap as the solution 66 warmed to room temperature, to remove any excess solvent.

The white residue which remained was taken up in about 40 ml. of chloroform and the solution was filtered. Then 200 ml. of pentane was added with stirring to the filtrate.

The mixture became slightly cloudy and in order to achieve precipitation of the product the flask and its contents were placed in Dry Ice for one half hour. Lowering the temperature in this way caused a white solid to crystallize

out of solution. The white precipitate was collected on a filter and redissolved in 20 ml. of chloroform. Another

200 ml. of pentane was stirred into the chloroform solution and the mixture was placed in Dry Ice for 30 minutes.

Again, a white solid precipitated and was collected on a filter. This recrystallization process was repeated

(usually two or three times) until melting point and infra red spectra could be reproduced on two successive recrys

tallizations, indicating that the product, C6 Hj HgS02 C6 Hj , was free of any unreacted diphenyl mercury. The diphenyl mercury was recovered from the various filtrates (2.86 g.) by removing the solvent under reduced pressure (27°C.J

20 mm.). Yield of C6H5 HgS02 C6 B, : 4?%*, 2.78 g. The preparation of C6 H5 HgS02 C$ H5 by a metathetical reaction between CgHjHgCl and NaS02C6Hj was not successful.

Phenylmercuric chloride (3.14 g.J 0.01 mole) was suspended

in 100 ml, of methyl alcohol and stirred vigorously at 0°C. (Later the temperature was lowered to -40°C. with the same results.) A solution of 1.64 g. (0.01 mole of NaS02 C6B5 in 10 ml. of water was added dropwise to the suspension.

The mixture was stirred for 1 hour at 0°C. Solvent was removed under reduced pressure (30°C.J 20 mm.) and the residue was treated with 50 ml. of chloroform. The result ing solution was filtered and the solvent was removed from the filtrate with a stream of nitrogen. The white solid which remained was identified as (CgH^gHg by its infrared spectrum. Yield: 2.4-9 g.

Benzyl(benzylsulfonyl)mercury( II), Cg iL CH, HgSO, CH, Cc IL .

Five grams (0.013 mole) of dibenzyl mercury was placed in a

20x6 cm. trap at -40°C. Dry sulfur dioxide was passed into the trap where it condensed, dissolving the mercury complex.

The liquid S02 solution became bright orange when the di benzyl mercury dissolved. When dissolution was complete

(about 50 ml. of solvent were needed) addition of S02 was halted and the solution was allowed to stand for 48 hours at -40°C. As the solution wanned to room temperature, the solvent was removed at 27 °0 . with a stream of nitrogen, a white residue remaining. This white solid was dissolved in

25 ml. of chloroform and the solution was filtered. Pentane

(200 ml.) was stirred into the filtrate giving a white pre

cipitate. The mixture was placed in Dry Ice for 15 minutes

to assure complete precipitation. The white solid was 68

collected on a filter and was immediately redissolved in

20 ml. of CHCI3 . Again 200 ml. of pentane was added with

stirring and the mixture was cooled in Dry Ice for 15 minutes* The resulting white precipitate was collected

on a filter and washed with 20 ml. of pentane. Usually

two such recrystallizations were sufficient to obtain pure

C6 fi5 CHg HgSOg CB^ C6 . If, however, a reproducible infrared

spectrum was not obtained, the recrystallization procedure was repeated until the spectra from two successive purifi

cations were identical. Unreacted dibenzyl mercury was

recovered (0.06 g.) by removing the solvent (27°C.; 200 mm.) from the filtrates* Yield of C6.H5 CI^ HgS02 CEg C6 H5 : 96%;

5.62 g.

It was necessary to store all samples of CsHjCHgHg-

S02.CH2 C6E; at Dry Ice temperatures. At room temperature

or at 0°C. and under nitrogen this derivative was very un

stable, decomposing to elemental mercury and dibenzyl sul-

fone in a matter of hours. Dibenzyl sulfone was identified

by its infrared spectrum. When normal laboratory light was

excluded from a sample maintained at 27 °0 . under nitrogen, the decomposition was noticeably slower (5 weeks) than in

the case of a sample which was exposed to light (4 hours).

EthylCethylsulfonyl)mercury(II), C,H* HgS0» Co S: , and

a compound of the empirical formula & HL, „ Hg» 0» S. Due to

the toxic nature of the vapors of diethyl mercury and the TABLE 3 Q* Analyses for Mercury Sulfonyl Derivatives

Compound______Calculated_____ Found CH S c H S

C6H5HgS02C6H5 34.56 2.39 7.63 34.63 2.50 7.87

C6H5CH2HgS02CH2C6H5 37.58 3.13 7.15 37.59 3.22 7.03

C2HsHgS 02C2H5 14.15 3.09 9.92 15.01 3.27 9.70

(C2H5Hg)2S02 9.14 1.91 6.10 9.14 2.00 6.01

0j Prepared "by insertion of S02

VO corrosive action of the liquid on human skin, all reactions and recrystallizations involving diethyl mercury and its derivatives were performed in a well-ventilated hood and rubber gloves were worn at all times. Five grams of diethyl mercury (0.019 mole) was placed in a 20x6 cm. trap at -40°C.

Dry S02 was passed into the trap where it condensed. Di ethyl mercury was not readily miscible with liquid S02 and so about 30 ml. of the dioxide was allowed to collect as a separate layer on top of the mercury compound. Then ad dition of S02 was discontinued and the contents of the trap were stirred vigorously with a cold glass rod in order to mix the two layers. The glass rod was chilled in Dry Ice to prevent loss of liquid S02 due to boiling caused by the heat of the rod.. The mixture was allowed to stand for 7 days at -78°0 . with occasional shaking to remix the liquid components. It was observed that the dissolution of

(C2 H5 )2Hg in liquid S02 gave a pale yellow solution. Ex cess solvent was removed with a stream of nitrogen as the solution warmed to room temperature and the remaining white solid was treated with 15 ml. of chloroform. Not all of the white solid was dissolved. The insoluble material was collected on a filter and washed with 5 ml, of chloroform.

Further purification was not possible due to the insoluble nature of this compound in all common solvents (See Table

12). Elemental analyses, however, indicated that this 71 derivative has an empirical formula corresponding to

C4 H,0 Hg2O2S (see Table 3). The white solid which was soluble in CHC13 was recovered from the filtrate by adding 200 ml. of pentane with

stirring and cooling the mixture for 15 minutes in Dry Ice.

A fluffy white solid precipitated and was collected on a

filter. The precipitate was recrystallized once more from

chloroform-pentane, collected on a filter, and washed with

20 ml. of pentane to give 2.62 g. (42% yield) of pure

C5 Hj HgS02 C2 Hj . No unreacted diethyl mercury was recovered and it was assumed to have been lost when excess liquid

sulfur dioxide was removed.

When this procedure was repeated using the same con

ditions, the yield of C2 H5 HgS02 C2 was consistent. How ever, the yield of the compound C4 H, 0 Hg2 02 S was not con

sistent and varied with each experiment. On one occasion

none of this product was detected.

Attempted Preparations of Sulfonyl Derivatives

Palladium system. Dimethylbis(triphenylphosphine)-

palladium(II) was prepared as described on page 32. Since

a pure sample of the compound was never isolated in this

study, 0.05 g. of impure [PCCgHj)^) 2 Pd(CH3 )2 (about 7.5X10*"5

mole) was placed in a trap (10x4 cm.) at -40°C. Dry sulfur

dioxide was passed into the trap where it condensed,

dissolving the white palladium complex to give a yellow solution. When all of the solid had dissolved (about

10-15 ml. of liquid S02 was needed) the excess S02 was evaporated in a stream of nitrogen as the solution warmed to room temperature. A yellow residue which remained was dissolved in about 5 ml. of chloroform. Pentane (100 ml.) was added with stirring. A yellow precipitate formed, was collected on a filter, and washed with about 10 ml. of pentane. Purification by alumina chromatography was not possible because the compound could not be eluted off the column. Chromatography on a cellulose column (5x10 cm.) eluting with chloroform gave one yellow band. Solvent was removed in a stream of nitrogen at 27°C. The yellow powder which remained gave the same infrared spectrum as the solid recovered from chloroform-pentane. The product of this reaction has not been identified. Elemental analyses are inconsistent and correspond to no probable formulation.

Yield: 0.02 g.; m.pt., 105°C. (dec.). Anal. Calcd. for

C3 8H3 6 0* P2 PdS2 : 0, 57.87; H, 4.57; S, 8.12*, P, 7.87\ mol. wt., 788. Calcd. for C3 8H3 602 P2 PdS: C, 62.98; H, 4.97\

S, 4.42; P, 8.56; mol. wt., 724. Pound: C, 48.87, 48.55,

47.09, 47.26; H, 4.59, 4.68, 5.97, 4.18*, S, 9.96, 9.25,

9.55; P, 6.64, 6.80; mol, wt., 716.

An attempt was made to prepare a sulfonyl derivative by metathesis using [p(Cg Hj )3] 2 PdC^ (page 32) and NaSO^^E^.

A solution of 0.351 g. (5xl0~* mole) of jp(C6 H5 )3] 2 PdC^ and 73

0.082 g. (5x10”' mole of NaSOgC^E^ in 75 ml. of N,1T- dimethylformamide was stirred under nitrogen for 7 days at 27°C. Solvent was then removed under reduced pressure

(20 mm.) at 27°C. and the residue was treated with 20 ml. of CHClj . A yellow solution and a white solid resulted.

The mixture was filtered using suction. The white solid was found to he NaSOgCgHj (0.08 g.). When the filtrate was evaporated (27°C.; 20 mm.) the remaining yellow residue was identified as unreacted {p(Cg )£j 2 PdClg

CO.30 g.). Both compounds were identified by their infra

red spectra. It should be- noted that this reaction can

not be carried out at higher temperatures because

[p(C6 H, )J J PdCl, , in solution, decomposes above 30°C.

Titanium system. Dimethyl titanocene was prepared

as described on page 51. One gram of (it-C5 Hj )2 Ti(CB3 )2 was dissolved in 10 ml. of pentane and the orange solution

was placed in a 20x5 cm. trap at -40°C. Dry S02 was

passed into the trap where it condensed to give about

30 ml. of liquid S02 . Liquid sulfur dioxide and pentane

are not miscible, however, and two layers formed, the

lighter pentane comprising the upper layer. As the sulfur

dioxide travelled to the bottom of the trap it extracted

the titanocene complex from the pentane solution. The

bright orange color of the pentane layer disappeared

while the S02 layer changed correspondingly from colorless 74 to deep red.1 This mixture was kept at -40°C. for 24 hours after which time nitrogen was bubbled through the trap to remove pentane and excess S02 • A gummy red residue remained. This was taken up in about 10 ml. of chloro form and 200 ml. of cold pentane was added with stirring.

An orange oil separated from the mixture. Pentane was decanted and the oil was redissolved in 5 ml* of CHC13 .

Chromatography on alumina was not possible. As soon as the solution of the red residue came in contact with the alumina, heat was given off and the resulting yellow band could not be removed from the column with CE^ Gig , CHC13 , or 0 % OH.

If the red residue was dissolved in 10 ml. of chloro form and the solution was evaporated under reduced pressure

(27°C.; 20 mm.), a red solid resulted. When attempts were made to redissolve a portion of this solid, it would not go into solution. Yield: 1 g. Anal. Calcd. for G12E,6 - 0^ S2 Ti: C, 41.60; H, 4.76; S, 19.02. Calcd. for C, 2 H, 6-

02 STi: C, 52.90; H, 5.87; S, 11.78. Found: C, 38.71*,

37.90; H, 4.77, 4.64; S, 13.63, 13.30.

1 When liquid S02 was condensed directly on solid (tc-CjHj^- TiCCHj)2 a violent reaction took place. Considerable heat was evolved, a foul-smelling yellow smoke was given off, and reduction to metallic titanium occurred. This rapid reduc tion was eliminated entirely by first dissolving dimethyl - titanocene in pentane. Another batch of (7t-C51% )2 TiCCHj )2 was prepared as before and reacted with liquid S02 , giving the same red gum as a product. Washing the residue with anhydrous ether caused the dissolution of some of the red compound.

Ether was removed from this solution with a stream of nitrogen at 27°C. leaving an orange solid (0.01 g.).

Analysis of this compound was not good but it is believed that decomposition began to take place almost immediately.

When a closed sample was opened after standing overnight at room temperature, the odor of cyclopentadiene was evident. Molecular weight determinations made immediately after the compound was recovered so that decomposition would be minimal, indicated a molecular weight of 338 .

The theoretical molecular weight for (71-C5 H5 )2 Ti(S02 CHj )2

is 336. Elemental analyses were not consistent, however, with this formulation. Anal. Calcd. for C12 K, 50*S2 Ti:

0, 41.60*, H, 4.76; S, 19.02. Pound: C, 44.96, 45.18*,

H, 4.04, 4.18; S, 11.15, 11.09, 11.29.

Titanocene dichloride (1 g.; 0.004 mole) and NaS02-

(g-tolyl)‘2 Hg 0 (0.86 g.*, 0.004 mole) were stirred under

nitrogen in 50 ml. of freshly distilled THP for 48 hours.

As titanocene dichloride reacted with the sodium salt the

solution became orange. The mixture was filtered using

suction and solvent was removed under reduced pressure

(27°C.; 20 mm.). An intractable red oil remained. 76

Attempts to crystallize the compound from chloroform- pentane were as unsuccessful as in the case of the di methyl derivative just described. On standing the oil apparently liberated cyclopentadiene, which was detected by its pungent odor.

Iron-tin system. A solution of tc-C5 1% Fe(CO)2 Na was prepared in the usual manner from 2.1 g. (0.006 mole) of

[tu-C5 Hj Fe(OO)^] 2 and excess 1% sodium amalgam (1.0 g. of

Na in 100 g. of mercury) in 100 ml. of freshly distilled

THF. The mixture was stirred at 27°C. under nitrogen for

12 hours. After removing the mercury with a syringe and hypodermic needle, 4 g. (0.012 mole) of triphenyltin chloride was added to the reaction mixture which was then stirred at 27°C. for one hour. The solvent was evaporated

(30°C.; 20 mm.): and the residue was extracted with chloro form. The volume of solution was reduced under vacuum

(27°C.J 20 mm.) to 5 ml. Pentane (200 ml.) was added with stirring to force precipitation of the yellow product

(2.1 g.) which was collected on a filter and washed with pentane. This preparation is a modification of that of

Gorish. (61)

L One gram (0.0023 mole) of 7i-C5 Hj Fe(C0)2 Sn(C6 % )3 was dissolved in about 30 ml. of liquid S02 at -40°C. and the

orange solution was allowed to stand at that temperature

for 24 hours. Then excess S02 was removed in a stream of nitrogen as the solution warmed to room temperature. The residual solid was taken up in about 5 ml. of chloroform and chromatographed on an alumina column (5x20 cm.) eluting with chloroform. Two bands appeared on the column: a yellow one containing 1.9 g. of unreacted 7t-C5 Hj Fe(C0)2 -

Sn(061^)3 followed by a very faint yellow-green band. This second band was collected and chloroform was removed with a stream of nitrogen leaving a yellow-green solid (less than 0.005 g. recovered). There was not enough of the product for microanalyses. The infrared spectrum of the compound did contain S-0 stretching frequencies indicating that S02 was present in the molecule. Subsequent attempts to prepare additional quantities of this compound were not successful.

Manganese system. Reactions between RaMn(C0)5 and sulfonyl chlorides were not as straightforward as expected.

The preparation of MaMn(C0)5 (62) was carried out in a 100 ml. three neck round-bottom flask fitted with a nitrogen inlet, a condenser and a mechanical stirrer. Essentially the same method that was used to make Tt-C5 Fe(C0)2 Ra (page

39) was employed here. A 1% sodium amalgam (54- g.i 0.37 mole Hg and 0.45 g.J 0.026 mole Na) was reacted with 1.0 g.

(0.0025 mole) of Mn2 (CO)10 in 50 ml. of freshly distilled

THE for one hour at room temperature. During the course

of this reduction the initial yellow-orange solution became colorless to yellow-green

Mng2 V(CO)w /1 o + 2 Na -- ^ -- > 2 NaMn(CO)5 (56) yellow- yellow- orange green

All reactants were then transferred to a dry box. The solution of NaMn(CO)5 was filtered by gravity into 0.885 g.

(0.005 mole) of C1S02 C6H5 with occasional stirring. Form ation of a white precipitate, shown later to be NaCl, was observed and the solution gradually changed from colorless to yellow. After all the THF solution of NaMn(C0)5 had been added, the reaction flask and contents were removed from the dry box and solvent was evaporated (27°C.; 20 mm.)

The residue was taken up into 5 ml. of chloroform and the solution was filtered. Slow addition, with stirring, of

100 ml. of pentane gave a pale yellow precipitate which was collected on a filter and washed with 20 ml. of pentane

When an attempt to recrystallize the solid was made, not all of it redissolved in chloroform. The insoluble matter was removed by filtration and another 100 ml. of pentane was stirred into the filtrate. The resulting yellow pre cipitate was collected on a filter and washed with 20 ml. of pentane. Yield: 1.4 g. Anal. Calcd. for C11I^Mn07S:

C, 39*28; H, 1.49; S, 9.52; mol. wt., 336. Found: C, 22.74

S, 8.17; mol. wt., 1198.

Exactly the same reaction was tried using NaMn(C0)5 , 79 prepared from 1 g. (0.0025 mole) of M n ^ C O ) ^ and excess

1 % sodium amalgam in 60 ml. of freshly distilled THF, and

0.575 g. (0.005 mole) of C1S02 CI^ . The product was re covered in the same way as the phenyl derivative and ex hibited the same behavior. Each attempt to recrystallize the pale yellow powder resulted in only part of the sample being soluble in CHC13 . Yield: 1.5 g. Anal. Calcd. for

CgHjMnOyS: C, 26.50*, H, 1.09*, S, 11.17? mol. wt., 274.

Found: C, 18.83, 19.02, 18.57, 18.58; H, 2.05, 1.87, 2.06,

2.20*, S, 13.50, 13.58, 13.97, 14.25*, mol. wt., 1200.

When the same reaction was tried using 0.49 g. (0.005 mole) of CHj S02 F (HaMn(C0)5 prepared as above), a different product resulted. After the THF solution of NaMn(C0)5 had been added to FS0Z CHj in a dry box, the solvent was evapo rated (27°C.; 20 mm.). The remaining solid was taken up in

10 ml. of chloroform and the solution was filtered into 100 ml. of pentane, A yellow precipitate resulted. The pro duct was collected on a filter and washed with pentane.

(Yield: 0.02 g.). Anal. Calcd. for C6H3Mn02 S: C, 26.30\

H, 1.09; F, 0; Mn, 20.01. Found: C, 22.96; H, 2.67*, F, 0*,

Mn, 35.38. Evaporation of the filtrate gave 0.7 g. of

Ena (C0)1 0 .

In another preparation methylmanganese pentacarbonyl

(2) and liquid sulfur dioxide were reacted. The 0 % Mn(C0)5 was synthesized by reacting HaMn(C0)5 with CH3 I. In 60 ml. 80 of freshly distilled THF, 0.5 g. (0.0012 mole) in Mn^CO).,,, and excess sodium amalgam were stirred under nitrogen for one hour to make NaMn(C0)5 . Unreacted amalgam was removed with a syringe and hypodermic needle and 0.36 g. (0.0025 mole) of methyl iodide was added to the THF solution under nitrogen. After stirring the mixture for one hour at room temperature, solvent was removed under reduced pressure

(27 °G.; 20 mm.) and pure CH3Mn(CO)5 was recovered from the residue by vacuum sublimation (50°C.; 0.01 mm.) onto a probe which was maintained at -78°C. by means of a Dry Ice- isopropanol slush.

Methylmanganese pentacarbonyl (0.1 g.J 0.0005 mole) was dissolved in about 15 ml. of liquid S02 at -ZK)°C. and the solution was allowed to stand for two hours at that temperature. Solvent was then removed in a stream of nitrogen as the solution warmed to room temperature. The yellow residue was dissolved in about 5 ml* of chloroform and the solution was filtered into 50 ml. of pentane. A yellow precipitate formed in pentane Sind was separated from the solution by filtration. (Yield: 0.08 g.). The

infrared spectrum of this solid was not the same as that

of the product derived from the reaction between NaMn(C0)5 and C1S02 CH^ . Insufficient supply of (G0)1 0 forced

discontinuation of the investigation of this system.

Perfluoroalkyl and -aryl systems. A 0.5 g» (0.014 81 mole) sample of x-Gg Hg Fe(CO)2 C6 F5 was dissolved in about

50 ml. of liquid S02 and allowed to react for 168 hours at

'-40°C. Excess sulfur dioxide was removed in a stream of nitrogen and the residue was taken up in 10 ml. of chloro form and filtered. Pentane (150 ml.) was stirred into the filtrate giving a yellow precipitate which was collected on a filter and washed with 10 ml. of pentane. The yellow product was shown by infrared spectroscopy to be the un reacted x-C5 Hg Fe(C0)2 Cg P5 (0.45 g.).

A perfluoromethylmolybdenum complex, x-C5EgMo(C0)3 CF3 ,

(0.3 g.? 0.001 mole), was dissolved in about 30 ml. of liquid S02 and allowed to react for 168 hours at -40°C.

Solvent was removed in a stream of nitrogen as the solution warmed to room temperature and the residue was purified by vacuum sublimation (50°C.*, 0.01 mm.) onto a probe cooled to -78°C. by means of a Dry Ice-isopropanol slush. Pure yellow x-CgHgMo(C0)3CP3 (0.28 g.) was recovered from the probe. No "insertion" product was found.

Acyl and benzoyl systems. The method of King and

Bisnette (7) was used to prepare x-C5 Hg Fe(C0)2 (C0CH3 ) and x-C5 Hg Pe(C0)2 (COCg Hg ). The sodium salt of cyclopentadienyliron dicarbonyl dimer was prepared in 60 ml. of freshly distilled THF from 1.77 g. (0.005 mole) of

[x-Cg Hg Fe(C0)^j 2 and excess 1% sodium amalgam as described on page 39. The unused amalgam was removed from the 82 reaction flask with, a syringe and hypodermic needle. A stoichiometric amount of acetyl chloride (0.01 mole;

0.78 g.) or benzoyl chloride (0.01 mole; 1.41 g.) was added to the THF solution and the mixture was stirred for three hours at 27°C. Solvent was removed (30°C.; 20 mm.) and the residue was treated with four 20 ml. portions of pentane. The pentane extracts were filtered using suction and the combined volume was reduced to about 10 ml. (27°C.;

20 mm.). Chromatography on an alumina column (5x30 cm.), eluting with pentane, gave two bands. The only moving band was a yellow one containing tc-C5 H5 Fe(C0)2 COCH3 (or te-C5 % -

Fe(C0)2 C0C6H5 ). A purple band due to unreacted cyclopentadienyliron dicarbonyl dimer stayed on top of the alumina column. Pure tc-C5 H5 Fe(C0)2 000% (or tc-C5 H5 Fe(C0)2 C0C6 Hg ) was recovered by evaporating the solution of the compound

(27°C.; 20 mm.).

One gram of te-C5 Hj Fe(C0)2 COCH3 (0.0045 mole) and one gram of 7t-C5 H5 Fe(C0)2 COCg H5 (0.0035 mole) were placed in separate 20x6 cm. traps. Dry S02 was passed into the traps

(-40°C.) where it condensed, dissolving the carbonyl com pounds. About 20 ml. of liquid sulfur dioxide was nece ssary for complete dissolution. The samples were allowed to stand at -40°C. for 12 hours. Solvent was then removed with a stream of nitrogen as the solution warmed to room temperature. Each residue was purified by alumina chroma tography as described above, eluting with, pentane. Only one band was eluted in each case. Solvent was removed with a stream of nitrogen to give 0.95 g« of n - C 5 Pe-

(C0 )2C0 CH3 and 0.90 g. of 7t-C5 H5 Fe(C0)2 (C0C6 H5 ), respec tively. No sulfonyl derivatives were detected.

Iron-silicon system. The compound 7i-C5 H5 Pe(C0)2 Si- (CHj)3 was prepared following the method of Piper and

Wilkinson (57) from tc-C5 H5 Pe(00)2 Na and ClSi(CH3 )3 . The sodium salt of cyclopentadienyliron dicarbonyl was pre pared as described earlier from 3*54- g. (0.01 mole) of

[tu-C5 H5 Pe(C0)£] 2 and excess 1 % sodium amalgam in 60 ml. of freshly distilled THE. To the solution of the sodium salt was added 0.56 g. (0.02 mole) of chiorotrimethyl-

silane and the solution was stirred for 4- hours under nitrogen at 27°C. Solvent was removed (30°C.J 20 mm.) and the residue was extracted with four 20 ml. portions

of benzene. The extracts were combined and filtered

through about 10 g. of alumina. The volume of solution was reduced to about 10 ml. in a stream of nitrogen at

27°C. and purification was begun on an alumina column

(5x30 cm.) eluting with benzene. An orange band con

taining Ti—O5 Hij Pe(C0)2 Si(CHj )3 followed by a purple band of [tc-Cj H5 Pe(C0)£j 2 appeared. Each band was eluted with

benzene and the solutions were evaporated under reduced

pressure (27°C.; 20 mm.). Prom the purple band 0.3 S. of Qir-Cj H5 Fe(CO)2J 2 was obtained. The residue from the orange

solution was further purified by vacuum sublimation (50°C.;

0.01 mm.) onto a water cooled probe. The orange subli mate, pure ic-Cj Hg Fe(00)2 SiCCHj )3 , was collected (2.50 g. J

0.01 mole) and the entire sample was dissolved in 40 ml. of

liquid sulfur dioxide at -40°C. The orange solution was allowed to stand at -40°C. for 24 hours. Solvent was then removed with a stream of nitrogen as the solution warmed

to room temperature, and the residue was taken up in10 ml.

of chloroform. Chromatography on an alumina column

(5x15 cm.)., eluting with CHC13 , gave two bands. The first band contained unreacted tc-C5 Hj Fe(C0)2 SiCCHj )3 (2.23 g.) which was recovered by evaporation of the solvent (30°C.i

20 mm.). The second band was a red one and moved very

slowly down the column. Solvent was removed with a stream

of nitrogen giving a red oil which was very unstable, even

under nitrogen. There were no carbonyl or sulfonyl stretch

ing frequencies in the infrared spectrum of the oil.

Preparation of Acetyl Derivatives of Tt-Cq Hk Fe(CO)9 OS,

Cyclopentadienyl(acetyl)(triphenylphosphine)carbonyl-

iron(II) , Tt-Cs E* Fe(C0)(C0CH, ) [PCC^S: ),] . One gram (0.005

mole) of cyclopentadienyl(methyl)dicarbonyliron (page 45)

and 1.31 g. (0.005 mole) of triphenylphosphine were diss olved in 10 ml. of freshly distilled THF and the solution

was refluxed for 48 hours. Moisture was excluded by means 85 of a CaCI^ drying tube. The solution was filtered to remove an insoluble brown decomposition product. A stream of nitrogen was used to evaporate the solvent and the orange residue was redissolved in 10 ml. of pentane. Puri fication was effected on an alumina column (5x20 cm.) eluting with pentane. One orange band appeared and was collected. Solvent was removed with a stream of nitrogen at 27 °G. to give 2.25 S« (99% yield) of pure orange X-C5H5 -

PeCC0)(00C^)[p(06H5 )3] . On one occasion when this reaction was run, the prod uct band was preceded by another orange band. This band was eluted and solvent was removed in a stream of nitrogen.

There was just enough of the orange compound for an infra red spectrum which showed one terminal C-0 stretching fre quency (1926 cm."*1 ) and no acetyl 0-0 stretching frequency.

The experiment could not subsequently be repeated.

Cyclopentadienyl(acetyl)(tributylphosphine)carbonyl- iron(II) , tu-CU Hq Fe(CO) (COCH, ) [p(CH, CB, CH, OH, ),] . One gram

(0.005 mole) of 7t-C5 H5 Pe(C0)2 CH3 (page 45) and 1.01 g. of tri-n-butylphosphine were dissolved in 10 ml. of freshly distilled THF and refluxed for 48 hours. The reaction was exposed to the atmosphere but moisture was excluded with a calcium chloride drying tube. Solvent was removed with a stream of nitrogen and the residue was taken up in 10 ml. of pentane. Chromatography on an alumina column (5x20 cm.) 86 using pentane eluent gave one yellow-orange band. An in soluble brown decomposition product remained on tbe alumina.

Solvent was removed from the yellow-orange solution ■under reduced pressure (30°C.; 20 mm.) giving 1.91 g. (97%) of pale orange tc-C5 Hg Fe(CO) (C0CH3 ) [pCCHa 0% CH* CHj )3] .

Cyclopentadienyl(acetyl)C triphenylphosphite)carbonyl- iron(II) , tt-Cc; K; FeCCOHCOCH, ) DpCOCa E* )J . Cyclopenta- dienyl(methyl)dicarbonyliron (1 g.^ 0.005 mole), prepared as described on page 45, and 1.55 g. (0.005 mole) of tri phenylphosphite were dissolved in 10 ml. of freshly dis tilled THF and refluxed for 48 hours. A calcium chloride drying tube was used to prevent moist air from entering the reaction vessel. The orange solution was filtered to remove an insoluble brown decomposition product and puri fication of the filtrate was effected on an alumina column

(5x20 cm.). Elution with a 50-50 mixture by volume of chloroform-pentane gave one yellow band. The solution was evaporated under reduced pressure (27°C.? 20 mm.). A yellow-orange crystalline product was recovered (2.46 g.;

98% yield) and identified as Tc-Cg Hg Fe(C0)(C0CH3 ) |j?(0C6 Hg )^J . Oyclopentadienyl(acet.yl)(tributylphosphite)carbonyl-

Iron(II), it-C.H.geCOO)(OOOa.)[P(OO^OH,OB,OH.)J . A solution of 1 g. (0.005 mole) of tz-Q5 Hg Fe(C0)2 CHg (page 45) and 1.25 g. (0.005 mole) of tri-n-butylphosphite in 10 ml. of freshly distilled THF was refluxed for 48 hours under TABLE 4

Analyses for Acetyl Derivatives

Compound Calculated Found C H P Fe C H P Fe

C5HsFe(CO) (COOfe) [p(C6H5 )3~] 68.95 5.06 6.82 69.06 5.00 6.56

CsH5Fe(CO)(COCH3)Jp (C4H9 )3] 60.90 8.90 7.86 14.20 60.60 9.3 0 7.83 14.13

C5H5Fe(CO) (C0CH3) |P ( 0C6H5 )2 62.15 ^.58 6.18 61.94 4.49 6.21

C5H5Fe(CO) (C0CH3 ) [p(0C4H9 )3] 5^-50 7 .91 7.01 55.13 8.13 6.82

\ 8 8 dry air. Chromatography on an alumina column (5x20 cm.) eluting with a 50-50 mixture by volume of chloroform- pentane gave one moving hand, a yellow one. Some brown decomposition product remained at the top of the alumina.

The yellow band was collected and solvent was removed under vacuum (27°C.*, 20 mm.). A yellow-orange liquid, tu-C5 % Fe(CO) (COCHj ) [p(0CI^ CHg CH* CHj )£] , remained (2.08 g. *, 96% yield).

m-CsK; Fe(C0)gCE| and pyridine, diethyl sulfide. p-toluidine, and p-chloroaniline. Five 1 g. samples of cyclopentadienyl(methyl)dicarbonyliron (0.005 mole), pre pared as described on page 4-5, were placed in separate 50 ml. round bottom flasks and each was dissolved in 10 ml. of freshly distilled THF. To the first solution was added

0.39 g. (0.005 mole) of pyridine; to the second, 0.4-5 g.

(0.005 mole) of diethyl sulfide; to the third, 0.54- g.

(0.005 mole) of p-toluidine; and to the fourth, 0.64- g.

(0.005 mole) of p-chloroaniline. The four reaction mix tures were refluxed for 4-8 hours, protected from moisture by calcium chloride drying tubes. At the end of that time solvent was removed with a stream of nitrogen and the in frared spectrum of each residue was taken. The pyridine reaction had completely decomposed the tc-C5 % Fe(C0)2 CHj to an insoluble black solid. No C-0 bands appeared in the spectrum of the pyridine reaction residue. The residues 89 from the other three reactions had no acetyl C-0 hands and all three spectra contained the two terminal C-0 hands of

7t-C5 Hj Fe(CO)2 CH3 . When these samples were later chromato graphed on an alumina column (5x20 cm.), eluting with pen tane, 7u—C5 H5 Pe(C0)2 CBj was recovered in essentially 100% yield.

tc—Cs EL; FeCOO)? CH« and (CEU^NI. One gram (0.005 mole)

of tc-C5 H5 Fe(C0)2 CH3 (page 45) and 1.00 g. (0.005 mole) of tetramethylammonium iodide were dissolved in 50 ml. of

freshly distilled THF and stirred under nitrogen for 4

days. The solution was filtered to remove a hrown decom

position product and the filtrate was evaporated (27°C.J

20 mm.). The residue was sublimed (30°C.; 0.01 mm.) onto

a cold finger which was maintained at -78°C. with a Dry-

Ice-isopropanol slush. Ahout 0.8 g. of te-C5 B5 Fe(C0)2 CH3

sublimed onto the cold finger. The material in the resi

due which did not sublime was identified as (CHj)kHI by

its infrared spectrum. Thus, essentially no reaction

took place between the two compounds.

Preparation of phenyl(phenylsulfide)mercury(II),

Ca Hg HgSCc Hg . Phenyl(phenylsulfide)mercury was prepared

using the general method of Takagi, Tanaka, and Tsukatani.

(63) Specific experimental conditions are those of the

author, however.

Phenylmercuric chloride (3«14 g.J 0.01 mole) was suspended in 200 ml. of absolute ethanol and stirred vig orously at -78°C., the reaction flask being immersed in a

Dry Ice-isopropanol slush. A solution of 1.10 g. (0.01 mole) of thiophenol in 20 ml. of absolute ethanol was added dropwise with stirring to the suspension. The mixture was stirred at -78°C. for 30 minutes and then was filtered using suction. The volume of the filtrate was reduced to about 150 ml. (30°C.; 20 mm.) and the alcohol solution was allowed to stand in Dry Ice for 24 hours. A white precipi tate gradually appeared. This was collected on a filter and recrystallized from absolute ethanol to give 1.55 g. (40% yield) of CgHjHgSCgHj, m. pt., 100-102°C. (literature value, 103.5°C.). Anal. Calcd. for C^B^oHgS: C, 37.21 ;

H, 2.58; S, 8.27. Found: C, 37.35*, H, 2.81*, S, 8.45.

If the temperature of the reaction was not maintained as low as -78°C. the only product formed was (Cgf^S^Hg.

Therefore, reaction conditions had to be controlled care fully.

Reactions of Sulfonyl Derivatives

Iron sulfonyl derivatives and halogens. One gram

(0.005 mole) of tc-C5 ]% Fe(C0)2 S02 CH3 was dissolved in 100 ml. of benzene and placed in an ice bath at 0°C. The 250 ml, round bottom flask which held the solution was fitted with a bubbler and an outlet. The outlet was connected to a trap which contained a saturated barium chloride solution. Chlorine gas was bubbled slowly through the benzene solu tion at 0°C. After about one minute the solution began to bubble very vigorously and addition of chlorine was discontinued. The evolved gas was passed through the barium chloride solution. For some time there was no observable change in the BaC]^ solution. Then a white precipitate began to form. Sulfur dioxide is known to form a white precipitate of BaS03 in barium chloride solution. (64) Therefore, S02 must have been evolved.

Accompanying the evolution of gas by the compound was the formation of a viscous oil1 which was immiscible with ben

zene. When bubbling had ceased the solution was heated in an oil bath to 80°C. and benzene was distilled off through a Liebig condenser. A dark, viscous residue, which showed no C-0 stretches in the infrared, remained. This residue was transferred to a micro vacuum distillation apparatus and distilled (26°C.J 10 mm.). A black tar remained in

the distillation flask; about 5 drops of a clear liquid was collected. Anal. Calcd. for C5 H5 CI: C, 62.50*, H, 5.20

Cl, 32.23. Found: C, 61.82*, H, 5.09*, 01, 32.42. The

elemental analyses and the boiling point indicate that the

1 The reaction between 7t-C5 H5 Fe(C0)2 Cl (59) and gaseous chlorine in benzene at 0°C. gave the same vigorous bubbling action and the formation of a viscous oil. Infrared examin ation of the oil showed that all CO had been lost. distillate was CgHjCl. The boiling point of C5 Cl is reported as 25°C. at 10 mm. pressure. (65)

The reaction of rc-C5 H5 Pe(C0)2 S02 C6 Hj and 71-C5 H5 Pe(C0)2 - S02 CI^ Cg Hj with chlorine gas followed the same pattern.

One gram of the sulfonyl derivative was dissolved in 100 ml. of benzene and chlorine gas was bubbled through the solution at 0°C. In each case there was complete decomposition of the compound. Sulfur dioxide was evolved, as well as an

other gaseous compound (presumably CO), and CjHjCl was re covered in small amounts by vacuum distillation. When the phenylsulfonyl derivative was used as the starting material, a few drops of C6 H5 Cl were also recovered by distillation

(30°C.; 0.01 mm.). The compound was identified by compar

ing its infrared spectrum with that of a known sample of

chlorobenzene. When tu-C5 H5 Pe(C0)2 S02 CH2 C6 H5 was used as the starting material, C5 H5 CI and CgHgCl were identified by infrared spectroscopy as the products. However, no benzylchloride was detected.

Essentially the same reaction occurred when the iron

sulfonyl compounds tc-C5 H5 Pe(C0)2 S02 CH3 and tu-C5 Hg Ee(C0)2 -

SOjjCgE^ were reacted with bromine. One gram of cyclopenta-

dienyl(methylsulfonyl)dicarbonyliron (0.005 mole) was

dissolved in 100 ml. of benzene. Bromine was added (0.80 g.

0.005 mole) to the solution at 0°C. There was evolution of

gas and, as in the reaction with chlorine, some of the gas 93 eous product gave a white precipitate when hubhled through a saturated barium chloride solution, indicating the evol ution of S02 . Bromine and the phenyl derivative reacted in exactly the same way. The reaction products were not examined. An infrared spectrum of the impure residue showed no GO stretches.

One gram (0.005 mole) of n-C5% Pe(C0)2 S02 0 % and 1.27 g. (0.005 mole) of iodine were dissolved in 100 ml. of ben zene and the solution was heated to 80°C. No gas was evolved at this temperature. Solvent was removed from the solution at 50°C. with a stream of nitrogen. The residue was transferred to a sublimation apparatus where iodine

(1.2 g.) was recovered by sublimation (50°C.; 0.01 mm.) onto a water cooled probe. The material which would not sublime was identified as unreacted ti-Cj Fe(C0)2 S02 0%

(0.98 g.). There was no evidence; of any product.

Mercury sulfonyl derivatives and chlorine. Phenyl-

(phenylsulfonyl)mercury (0.5 g.» 0.001 mole) was dissolved in 50 ml. of freshly distilled tetrahydrofuran and main tained at 0°C, in an ice bath. The 250 ml. round bottom flask whibh held the solution was fitted with a bubbler and gas outlet. The outlet was connected by a piece of

Tygon tubing to a trap, which contained a saturated so lution of barium chloride. As chlorine was bubbled through the THF solution a white precipitate formed and then quickly dissolved. At no time during the reaction did the barium chloride solution become cloudy. After 15 minutes addition of chlorine was halted and solvent was removed (30°C.; 20 mm.). The white residue was treated with 20 ml. of chloroform. Not all of the residue diss olved. The insoluble portion was collected on a filter and washed with chloroform. An infrared spectrum was taken of this solid, identifying it as phenylmercuric chloride (0.75 g. recovered)). Solvent was removed from the filtrate with a stream of nitrogen at 27°C. A color less liquid, identified as benzenesulfonyl chloride from its infrared spectrum, remained in about 0.1 gram yield.

Ethyl(ethylsulfonyl)mercury (0.5 g«» 0.0015 mole) was dissolved in 50 ml. of freshly distilled THF at 0°C.

The flask containing the solution was connected to a satu rated BaClg solution as described above. Chlorine gas was bubbled through the THF solution at 0°C. for 15 minutes.

There was no formation of a precipitate in either the re action vessel or the barium chloride solution. Solvent was removed from the THF solution (30°C.; 20 mm.) and the residue was washed with chloroform. Elemental analyses

showed the insoluble portion to be HgCl^ . Anal. Calcd.

for HgClg : Cl, 26.10. Found: Cl, 26.49. The filtrate was then evaporated at 27°C. with a stream of nitrogen

giving a colorless liquid. The infrared spectrum of this 95 liquid identified it as ethanesulfonyl chloride.

Sulfonyl derivatives and chloride ion. One-half gram samples of tt-C5 H5 Fe(CO)2 S02 CH3 and Cg Hg HgS02 Cg Hg were diss olved separately in 5 ml. of 6M HC1. After 12 hours the acid was removed under reduced pressure (30°C.’, 20 mm.)

leaving the original sulfonyl derivatives 100% intact.

7t-0q S; Fe(C0)9 SO, Cg E; and NaBHj, . Two grams (0.006 mole) of 7u-C5 Hg Fe(C0)2 S02 Cg Hg was dissolved in 10 ml. of freshly distilled THF and cooled to 0°C. in an ice bath. To this

solution, 0*30 g. (0.006 mole) of sodium borohydride was

added with stirring. There was considerable bubbling and

the formation of an insoluble brown precipitate. When all

bubbling had ceased solvent was removed (27°C.*, 20 mm.)

and an infrared spectrum was taken of the residue. There were no peaks in the C-0 stretching frequency region, in

dicating that the carbonyl complex had decomposed.

Heating sulfonyl derivatives. One gram samples of

71—C5 Hj Fe(C0)2 S02 CHj Cg Hg (0.003 mole) and C6 H5 CHj, HgS02 CHg C6 H5

(0.004- mole) were dissolved separately in 20 ml. of dioxane

and refluxed under nitrogen at 101°C. for two hours. At the

end of this time solvent was removed (50°C.; 20 mm.). In

the case of the iron sulfonyl derivative, the yellow solid

which remained was redissolved in 10 ml. of chloroform.

Addition of 200 ml. of pentane, with stirring, effected the

precipitation of 0.95 g. of the starting compound, Tt-CgHgFe- 96 (C0)2 S02 CHa C61% , which, was collected on a filter. The white residue from the mercury reaction was taken up in

30 ml. of chloroform. The volume of solution was reduced to about 10 ml. in a stream of nitrogen and 100 ml. of pentane were added with stirring. A white precipitate of C6 CHg HgS02 CE^ C6 (0.09 g.) was collected on a filter and washed with pentane.

One gram of % - C 5 Hg Fe(C0)2 S02 C6 (0.003 mole) was dissolved in 100 ml. of toluene and the solution was re fluxed under nitrogen at 110°C. for 5 hours. At the end of this time solvent was removed (50°C.j 20 mm.) and the residue was taken up in about 5 ml. of CHC13 . Chromato graphy on an alumina column (10x3 cm.), eluting with chloroform, gave only one band. Evaporation of solvent in a stream of nitrogen yielded 0.96 g. of cyclopentadienyl-

(phenylsulfonyl)dicarbonyliron(II). When this same ex periment was tried under carbon monoxide the sulfonyl com pound was, again, unchanged after refluxing in toluene at

110°C. for 5 hours.

Ultraviolet Irradiation of Sulfonyl Derivatives

Irradiation of iron sulfonyl compounds. Two grams of

tc-C5 Hj Fe(C0)2 S02 CH3 (0.01 mole) was dissolved in 100 ml. of benzene and transferred to the reaction vessel used for

ultraviolet irradiations. (See Figure 4) The reaction

vessel was connected to a gas burrette and the solution was irradiated using no light filter. During the 72 hours of irradiation, 94.2 ml. of gas were evolved. The benzene solution was filtered to remove an insoluble brown com pound which had formed. This solid gave no carbonyl stretching frequencies in the 1900-2100 cm.*"1 region in the infrared. The volume of the filtrate was reduced to about 5 ml. with a stream of nitrogen and purification was effected on an alumina column (5x20 cm.) eluting with chloroform. Two bands appeared on the column. The first one, orange, contained a trace (less than 0.001 g.) of ferrocene, which was identified by its infrared spectrum.

The second, yellow band was due to unreacted n-CjH5 Fe- (C0)2 S02 CHj (0.42 g.). This was recovered by evaporating the solution under reduced pressure (27°C.; 20 mm.).

The phenylsulfonyl and benzylsulfonyl derivatives of cyclopentadienyliron dicarbonyl reacted in the same way when irradiated with ultraviolet light. There was con siderable decomposition to an insoluble brown compound which contained no carbonyl groups. Ferrocene was pro duced in very small amounts and the unreacted starting compound was recovered in about 20% yield.

Irradiation of mercury sulfonyl compounds. One gram

of ethyl(ethylsulfonyl)mercury (0.003 mole) was dissolved

in 10 ml. of freshly distilled THF. Benzene was slowly

added to the solution in three 30 ml. portions, stirring vigorously. If benzene was added rapidly without careful

stirring the C2 HgS02 C2 H5 precipitated out of solution

and. could only be redissolved by adding a considerable

amount of THF (about 40 ml.). The solution was trans

ferred to the ultraviolet irradiation reaction veasel

(See Figure 4) and irradiated for 72 hours using no filter.

During this time 4.8 ml.1 of gas was evolved. The solution was filtered to remove a small amount of elemental mercury

which had formed. Solvent was then removed under vacuum

(30°C.; 20 mm.) and the white solid which remained was

dissolved in about 10 ml. of chloroform. Pentane was

added with stirring and the solution was placed in Dry Ice

for 15 minutes to induce precipitation. The white preci

pitate was collected on a filter and identified as CgHjHg-

S02 C2H5 by means of its infrared spectrum (0.90 g. re

covered). There was no evidence of any other product.

Similarly, one gram (0.004 mole) of C6 01^ HgS02 -

C6 was dissolved in about 10 ml. of freshly distilled

THF and 90 ml. of benzene. The solution was irradiated

for 72 hours using no filter for the lamp. During this

time 6.1 m l.1 of gas was evolved. The solution was fil

tered to remove any elemental mercury which had formed

and solvent was evaporated (30°C.J 20 mm.) from the fil

trate. The white residue was examined in the infrared

1 Corrected to STP 99 and was identified as C6 H5 GE^ HgS02 CE^ C6 H5 (0.94 g. re covered). There was no evidence of any other product.

Cyclopentadienyl(phenyl)dicarbonyliron(II), Na(p-SO{>-

Cfi Hfc CILt ) * E> 0, and Liquid Sulfur Dioxide. Two grams of ti-Cj H5 Fe(CO)2 C6 H5 (0.008 mole), prepared as described on page 36, and 3.64 g. (0.02 mole) of Na(p-S02C6H*CH, )'2Hg0 were dissolved in 30 ml. of methanol. The solution was placed in a 20x5 cm. trap maintained at -40°C. with a Dry

Ice-isopropanol slush and sulfur dioxide was passed into the trap where it condensed, giving a total volume of about

90 ml. of solution. The reaction was allowed to proceed at

-40°C. for 24 hours during which time much of the Na(p-S02-

C6 H* CHj) precipitated out of solution. Solvent was removed with a stream of nitrogen as the mixture warmed to room temperature and the residue was taken up in about 10 ml.

of chloroform. Insoluble Na(£-S02 C6 H*01% ) was removed by

filtration (3.5 g. recovered) and the filtrate was evapo rated using a stream of nitrogen. The yellow residue was

dissolved in about 5 ml. of chloroform and 150 ml. of pen

tane was added to the solution with stirring. The yellow

precipitate which formed was collected on a filter and redissolved in about 1.5 ml. of CDC13 . An NMR spectrum

of the compound showed a signal at 2 .0 -2 .57'and one at

4.757 indicating the presence of te-C5 Hj Fe(C0)2 S02 C6 H5 .

There were no signals at 4.917 or 7.587 to indicate that 100 any exchange had occurred to produce % -G5 H5 Fe(C0)2 (£-S02-

Cg CH5 ) . RESULTS AND DISCUSSION

Investigation of the Iron

Sulfonyl Derivatives

Since no alkyl- or arylsulfonyl derivatives of metal complexes had been reported prior to this investigation,

it was first necessary to determine whether a stable com pound of this type could be prepared. The simplest method

of synthesis appeared to be reaction between a metal car bonyl anion and an appropriate sulfonyl chloride. (Other methods, to be discussed in the following section, were

later employed to prepare sulfonyl derivatives.) Because

of its availability in this laboratory and its proven

ability to participate in CO insertion reactions (2), the

cyclopentadienyliron dicarbonyl system was selected for

initial study.

When the sodium salt of cyclopentadienyliron dicar bonyl was reacted with a sulfonyl chloride, small amounts

of a k-C5H5 Pe(CO)2S02R complex were produced. Having thus

established that these compounds can be synthesized, the most significant part of this research - preparation of

new derivatives by sulfur dioxide insertion - was begun.

The reaction between sulfur dioxide and alkyl (aryl)

101 102 derivatives of cyclopentadienyliron dicarbonyl gives stable, crystalline products which have one S02 per each iron, as shown by elemental analyses. A comparison of the infrared spectra of the compound formed in the reaction between S02 and 7t-C5 H5 Fe(C0)2 CHj , for example, and the sulfonyl product of reaction between C1S02 CH3 and x-C5 H5 Fe(C0)2 Na showed that the two compounds are identical. Still, it was necessary to elucidate the mode of bonding in the FeS02R moiety. This was established primarily by means of a proton magnetic resonance study and examination of the infrared spectra of the derivatives.

Preparation of x-CU EU FeCC0)i> R. Sulfonyl derivatives of cyclopentadienyliron dicarbonyl were prepared by four different methods. The sndium salt of a sulfinic acid was reacted with cyclopentadienyliron dicarbonyl chloride to give good yields of the iron sulfonyl complex.

x-C5 Hj Fe(C0)2 Cl + NaS02 R 12- x-C5 H= Fe( C0)2 S02 R +NaCl (57)

±1T? - —p 05115 tt , —p 05 TT fFToxij 73-90%

Similarly, the reaction between the sodium salt of cyclopentadienyliron dicarbonyl and a sulfonyl chloride gave small amounts of the sulfonyl derivatives and slightly larger yields of both cyclopentadienyliron dicarbonyl chloride and the parent dimer. 103

7i-C5H5 Fe(00)2Na + C1S02R > 7t-C5 R; Fe(C0)2 S02 R + NaCl 2% R- -CH3 , -C2 H5 , -C6 H5 + tt-C5 H5 Fe(C0)2 Cl + [tt-Cj H5 Fe-

Reaction between rc-C5 B5 Fe(C0)2 Na and FS02 CH3 gave essentially the same yield of cyclopentadienyl(methylsulfonyl)dicarbonyliron(II) (2%) and a 23% yield of

[m-Oj Hj Fe(C0)2^] 2 . The fact that no tu-C5 H5 Fe(C0)2 F was re covered is not surprising since the fluoride derivatives of most metal carbonyls have never been isolated.'1' If any tc-C5 H5 Fe(CO)2 F is formed, it probably is an unstable spe cies which may undergo decomposition to a fluorine-contain ing compound and cyclopentadienyliron dicarbonyl dimer.

This could explain the higher yield of [jc—G5 H5 Fe(CO)7j 2 in the reaction using FS02 CHj .

It is possible that what actually took place in these reactions was initial formation of ir-C5 H5 Fe(C0)2 X and NaS02 OH3 followed by reaction between these two compounds, as described in Equation (57)» to give the sulfonyl com plex. If this is the case, the relatively short time allowed for reaction (15 min.) may account for the low yield of m-C5 H5 Fe(C0)2 S02 CH3 , inasmuch as cyclopentadienyl iron dicarbonyl chloride and the sodium salts of sulfinic

Notable exceptions are PtF2 (C0)2 [^(CgHj)^ 2 , PtF2 (C0)2 - [P(0C6 H5 )3] 2 , Pt(C0)2 F8 , and Rh(C0)2 F3 reported by D.W.A. Sharp and co-workers (16, 66 ). 104- acids react slowly under the same conditions, requiring about twelve hours to go to completion. Any unreacted n>05 Hg Fe(CO)2 F, again, would most likely decompose to the dimer and a fluorine-containing compound.

Another sequence of reactions could be responsible for the production of ir-Cg .Hg Fe(CO)2 S02 CHg from ru-CgHgFe- (CO)2Na and FS02 CHg . A third method of preparing the sul fonyl derivatives involved the reaction of cyclopenta dienyliron dicarbonyl dimer and a sulfonyl chloride.

[jc-G5 Hg Fe(CO)2] 2 + C1S02 R -- > 71-C5 Hg Pe(CO)2 Cl + n-C5 Hg Fe- (C0)2 so2r

R= -CHj , -C 2 Hj , -Cg H5 70* 90% (59)

Methanesulfonyl fluoride also reacts with the dimer to give low yields of 7t-C5 Hg Fe(C0)2 S02 CH3 , although, again, no 71-Cg Hg Fe(C0)2 F was isolated from the reaction mixture.

prt-Cg Hg Fe(CO)^] 2 + FS02 CH3 — > rc-Cg Hg Fe(CO)2 S02 0% (60) 1%

Since the dimer is a product in the reaction between

7t-Cg Hg Fe(C0)2 Na and FS02 CH5 , it could then react further with FS02CHj to form the methanesulfonyl derivative.

Finally, sulfonyl derivatives were prepared by re action of a cyclopentadienyliron dicarbonyl alkyl or aryl with sulfur dioxide. Sulfur dioxide was condensed at

-40°C. into a trap containing a carbonyl alkyl or aryl 105

x-C5 H5 Fe(C0 ) 2 R + S02 °°-'•- ) x-C5 Hg Fe(C0 ) 2 S0 2 R (61)

R^-GHj , -C2 H5 , -Cg H5 , -CHa C6 H5 , -£-Cg B* CH,

tc-Oj H5 Fe(CO)2 2 (CHg )3 + SO* > x-C5 H5 Fe(C0)2 S02,-

(CHj, )3 Fe(CO)2 (x-C5 H, ) + x-C5 H5 Fe(CO)2 S02 (CHg )3 S02 Fe-

(C0)2 (tc-Oj Hj ) (62) complex which dissolved to form a red solution. Evapo ration of S02 at room temperature immediately after the carbonyl had dissolved was followed "by alumina chroma tography of the residue to give, in most cases, good yields of the sulfonyl derivatives. (See Table 5) The reaction of sulfur dioxide took place most readily with the methyl and ethyl compounds. This was indicated by an instantaneous color change from orange to red as the carbonyl dissolved and by essentially 100% conversion to the sulfonyl derivative. Under the same conditions the reaction proceeded more slowly with the other compounds.

Qualitatively, the relative rates of reaction for x-CjHj-

Fe(C0)^E and S02 are: x-Gj H5 Fe(U0)2 CB^ and -C2H5 y [x-CjHj-

FeCCO)/| 2 (CH* )3 > x-Cj H, Fe(C0)2 CH* Cg % > x-Cj H5 FeCC0)2 Cg Hj >

X - C 5 Hj Fe(C0)2 C£-C6 H* CH, ). Since the insertion1 reaction must ultimately involve the breaking of a metal-carbon bond, this order of reaction

■^The word insertion is not used to indicate a mechanism here. 106 rates is not unexpected. The compounds having a stronger metal-carbon bond, i.e., Fe-CgHg and Fe-C6H*CHj (67) i re

act most slowly. Other experiments in this study show

that perfluoroalkyl and -aryl complexes, which should

have very strong metal*-carbon bonds due to the electron withdrawing nature of the fluorines in the R groups and

M C it-bonding, do not insert S02 at all under conditions

employed in this investigation. If it is assumed that

a weak three-centered bond between the metal, the incoming

ligand (S02 ), and R is formed, a steric argument can also

be used to explain the observed order. It would seem that

the reaction rate is slowest for those compounds having a

bulky group such as a phenyl ring directly bonded to the

metal. A nucleophilic attack of the S02 molecule on the

metal as well as the formation of a weak carbon-sulfur bond

may be hindered by the bulk of the R group.

Some evidence is available to support the nucleophi

lic attack of S02 on the metal. The rate of the insertion reaction of m-CjHjPe(C0)2 CH3 appears to be dependent upon

the concentration of sulfur dioxide. When the concentra

tion is very high, i.e., in liquid S02 , the reaction pro

ceeds rapidly, but at low concentrations (in pentane so

lution) at 27°C. the reaction is slow.

Assuming there is a nucleophilic attack by S02 ,

three possible mechanisms may be considered in an attempt 107

to explain the ultimate attachment of the alkyl or aryl

group to sulfur dioxide.

First, R may migrate onto an adjacent carbonyl to

form a coordinately unsaturated acetyl species\ this is

followed by nucleophilic attack of S02 and simultaneous migration of R onto S02 . This mechanism is not likely

fast S02 tt-C5 E5 Fe(CO)2 R ( s TC-C5H5 Fe(CO)(COR) > tu-C5 H5 Fe(CO)2 - S02R (63)

to occur since S02 (either as a solvent or nucleophile)

has coordinating ability.

A more reasonable explanation would be that a solvent

(S02 ) or ligand (S02 in pentane solvent) assisted migra

tion of R onto carbon monoxide, similar to the mechanism

proposed by Mawby, Basolo, and Pearson for the methyl-

manganese pentacarbonyl system (See page 10), takes place

followed by a rapid migration of R onto S02 .

x-C5 H5 Fe(CO)2 R + S02-^±tu-C5 H5 Fe(CO) (C0R)(S02 )— >Tt-C5 H5 Fe- (C0)2S02R (64)

Certain qualitative observations in this study

support this mechanism. As already noted, the rate of

the insertion reaction seems to depend upon the concen

tration of sulfur dioxide. Also, whereas S02 insertion

proceeds rapidly in liquid S02 and reasonably fast in

pentane, good nucleophiles such as phosphines (to be dis- 1 0 8 cussed later) react very slowly in ether or tetrahydrofuran solution (48 hours) with 7t-C5 H5 Pe(C0)2 OH3 , even at

65°C., to give the acetyl derivatives, n - C 5 HgFe(CO)-

(COCH3 )H?3 (R -C6 Hg , -C* Hg , -0C6Ej, -OC^Hg). A three-fold excess of the nucleophile, however, reduced reaction time to about 30 hours. (Thus, there appears to be a strong dependence of the reaction rate on the nature of the nu cleophile as well as its concentration, whether solvent or ligand.

Considering yet a third mechanism, the attack by sulfur dioxide may be accompanied by direct migration of the R group onto S02 . It is difficult to distinguish

CO / ^ S 02 tu-C5 Hg Pe(C0)2 R + S02^ n - C s B s t e : — > H-C5 H5 Pe(CO)2 S02 R \ 'H - CO (65) this mechanism from the preceding one using the evidence

available. If a stable compound of the type tc-C5 H5 Fe(CO)- (C0R)S02 can be made, the solvent assisted mechanism must

be eliminated because then this acetyl-sulfur dioxide com

pound, rather than a sulfonyl derivative, would be the

product. In order to resolve this problem the acetyl and

benzoyl derivatives of cyclopentadienyliron dicarbonyl

were reacted with sulfur dioxide. It was thought that

perhaps one carbonyl group would be replaced by S02 to

yield n - G 5 H5 Fe(CO)(C0R)S02 , which then could remain 109 unaltered and therefore definitely eliminate path two, or which could rearrange to 7t-(^ H5 Fe(CO)* S02 R. If the former compound had been isolated, then R group migration from CO to S02 would have in all probability taken place, thereby providing evidence for mechanistic route 2 (See

Equation (64)). However, no reaction occurred, even after

12 hours. The result is not really very surprising since the compounds 7u-05 H5 Pe(C0)2 (COR) are quite inert and de- carbonylate only under the influence of ultraviolet light.

(7) Thus, the approach above did not resolve the mechan istic dilemma. Additional studies are necessary to clarify the issue.

Physical properties of the sulfonyl derivatives. The sulfonyl derivatives of cyclopentadienyliron dicarbonyl are all yellow, crystalline compounds with sharp melting points. (See Table 5) The solids appear to be indefi nitely stable in air, showing no signs of decomposition after several months? decomposition to an insoluble brown solid takes place in chloroform solution after about 24- hours of exposure to air. The complexes are readily sol uble in benzene, chloroform, dichloromethane, alcohols,

HC1, acetonitrile, tetrahydrofuran, acetone, and water, but are insoluble in pentane, hexane, cyclohexane, and carbon disulfide. The dinuclear compounds, [rc-CjI^Fe-

(C0)£| 2 (S02 )(CH2, )3 and [x-C5 H5 Pe(C0)2J 2 (S02 )2 (CHg )3 , are TABLE 5

Some Physical Properties of Iron and Molybdenum. Sulfonyls 3/

mol.wt. Compound Color m.pt.°C. Calcd. Found Solubility

CsHsFe(C 0 )2 S 0 2 CB3 yellow 135 256 262 All these compounds are soluble in H20, CHG13, C5H5Pe(C0)2S02C2H5 yellow 165 270 306 CH2C12, CH3CN, C6H5N02, acetone, and liquid S02 . CgHgFe(C0)2 S02 C 6 H 5 yellow 137 518 348 They are moderately sol uble in C6H6, and insol CsHsFe(C0)2 S02 CH 2 C 6 H 5 yellow 117 332 337 uble in pentane, hexane, and carbon disulfide. C 5 H 5 Fe(C0)2 S0 2 (p-S02 G 6 H4GH3 ) yellow 212 332 352

[CgHgFe (C0)2] 2 S02 (GH2 )3 yellow 86 46 0 473 yellow- JCgHsFe (C0)2j 2 (S02 ) 2 (CH2 ) 3 185 524 503 orange C5H5Mo(CO)3S02CH3 gold 158(dec.) 324 336

a. Prepared by insertion of S02 110 Ill less soluble in benzene and chloroform. These two deri vatives are slightly hygroscopic and tend to become gummy in moist air. Nuclear magnetic resonance spectra (to be discussed later) show very sharp proton signals, indi cating that the compounds are diamagnetic.

Nuclear magnetic resonance studies. Nuclear magnetic resonance spectra of the iron sulfonyls are listed in

Table 6 . The assignment for the hydrogens in the R group, in most cases,1 precludes structures in which both R and S02 are coordinated separately to the metal. For example, cyclopentadienyl(methylsulfonyl)dicarbonyliron(Il) shows sharp proton signals at 4-.75£ (TC-CgHg) and 6.857T (CH3 ).

The methyl proton signal for 7t-C5 Hg Fe(CO)2 CH3 is at a much higher frequency (9 .89£) (68 ) indicating that hydro gens belonging to an alkyl group bonded directly to a transition metal experience strong diamagnetic shielding by the metal. The ll values for methyl proton resonance in CHg S02 Cl and CHgS02 F, 6.36 and 6.73? respectively, (69) are more similar to the value for ic-Cg % Fe(CO)2 S02 CEg .

Deshielding of the methyl protons, however, can be

1It is difficult to make a conclusion of this nature from the spectrum of ti-C5 Hg Fe(CO)2 S02 C5 Hg because of the complex nature of the signal assigned to the phenyl protons. Furthermore, effects of deshielding are difficult to assess inasmuch as there are no hydrogens on the carbon bonded directly to iron. TABLE 6

Proton Magnetic Resonance Spectra of Tf-CsHsFe(CO)2R &

R- Chemical shift, "t Relative Intensity Assignment

SO2CH3 4.75 (s) 5 C5H5 6.85 (s) 5 ch3

SO2C2H5 4.58 (s) 5 C5H5 6.70 (q; J~8 cps) 2 ch2 8 .h-9 (t; J~8 cps) 5 ch3 so2c6h5 2 .0-2.5 (m) 5 c6h5 4.75 (s) 5 g5h5

S02CH2C6H5 2.4 (s,hr) 5 c6h5 4.70-(s) 5 C5H5 5.61 (s) 2 ch2

SO2C6H4CH3 2.11-2.44 (m) 2 s < 5-c

2 .50-2.82 (m) 2 s-Q)-o H 4.91 (s) 5 G5H5 7.58 (s) 5 CHS

SO2CH2CH2CH2 4.60 (s) . 10 C5H5 6.48 (t; J~6 cps) 4 SO2-CH2 7.51-7.51 (m) 2 C-CHs-C

CHsCeHs 2.80 (s,hr) 5 c6h5 5.51 (s) 5 C5H5 7.25 (s) 5 CH3

CH3 b 5.50 (s) 5 C5H5 9.89 (s) 3 ch3

C2H5 C 5.40 (s) 5 C5H5 8.45 (q; J~8 cps) 2 ch2 8.75 (t; J~8 cps) 3 CHa

Qi ' ^ In CDCI3 unless otherwise noted s-singlet m^multiplet In CCI4. See reference 7 t=triplet t>r=broad In CeH6 . See reference 7 q-quartet 113 accounted for by formation of either an acetyl or a sul fonyl group. A notable absence of any absorptions in the

14-50-1800 cm"'*' region of the infrared spectrum, which will be discussed! in more detail in the next section, indicates that the products are not acyl complexes.

The knowledge that the S02 molecule has, indeed, in serted between the metal and the R group raises a question concerning the bonding in the FeS02R moiety. Examination of the nuclear magnetic resonance spectra of the ethyl and benzyl iron sulfonyls can answer this question.

Figure 5 shows the three most probable structures which these compounds could have. In structures II and

III the methylene protons are not magnetically equivalent and would be expected to give an AB type spectrum (a pair of doublets). (70) The splitting, which has been ob served for some sulfinic esters (7 1 , 72 ), is thought to be derived from the lack of symmetry associated with the sulfinate sulfur. Structure I has no asymmetric sulfur; the CHg protons will have identical magnetic environments and should give a much different spectrum. The quartet of relative intensities 1 :3 :3;1 at 6 .70"t due to the methylene hydrogens of the ethyl derivative and the sharp singlet at 5.61); in the case of the benzyl derivative are consistent with structure I. The higher affinity of low valent iron for sulfur rather than oxygen (53) lends 114 credence to this structural assignment, as well. An oxygen-bonded species such as structure III seems additionally improbable in view of 7t-bonding to be dis cussed later.

Figure 5

Possible Structures of 71-C5 Hj Fe(C0) 2 S02 CHj R

I II III

R = -CH3 , -Cg H5

The significance of the reactions which produced

Tt— C5 H5 1*6 (00)2 S02 R from-the sodium salt of cyclopenta dienyliron dicarbonyl and a sulfonyl chloride, or from tc-CjFe(CO)201 and the sodium salt of a sulfinic acid cannot be overlooked. Reasoning qualitatively, structures

I and III are more likely to be formed than structure II because II requires rearrangement of the -S02R moiety from that containing a sulfone to one with a sulfinic ester linkage, whereas the other two do not. Since some

of these reactions were carried out over several hours, however, the -S02R group had every opportunity to bond

in any one of the three possible ways suggested in Figure 5 . In all cases, the product obtained from the above men tioned reactions was identical with that isolated from the reaction between S02 and the appropriate alkyl or aryl complex. Therefore, structure I clearly represents the most favored mode of bonding, which is the same as that found in sulfonyl chlorides and organic sulfones.

Because of the similar physical properties of all of the

iron sulfonyl derivatives, the entire series has been assigned this sulfonyl-type linkage.

TABLE 7

Gyclopentadienyl Proton Chemical Shift Position

Por it—C5 E> Pe(CO)2 S02 R

R =

-S 0 2 0% 4 . 7 5 -SO^CgHj 4 . 5 8 -S 0 2 C6 H; 4 . 7 0 -S 0 2. CBfc, Cg Hg 4 . 9 0 - S 0 2 C6 H* CBj 4 . 9 1

-CHj 5 . 3 ° I -C2 5 . 4 0 a -C 6 H5 5*2? -CH^CgH; 5 .3 1

aSee reference (7)

The M R data afford another interesting observation.

Table 7 contrasts the cyclopentadienyl proton chemical

shift positions of the sulfonyl and alkyl (aryl) deriva

tives of cyclopentadienyliron dicarbonyl. Rot only the 116

alkyl and aryl groups are deshielded as a result of the

S02 insertion; the t values for the cyclopentadienyl

protons show a noticeable shift downfield, indicating

that the H5 moiety is also being deshielded. This

deshielding could be caused by the formation of a bond with some ir-character between iron and sulfur. Back do

nation from filled non-bonding orbitals on the metal to

empty orbitals on the sulfur would shift electron density

away from the cyclopentadienyl group. Figure 6 illus

trates the deshielding of both the benzyl and cyclopenta

dienyl protons in the sulfonyl derivative.

Infrared spectroscopic studies. Any it-bonding be

tween the sulfur and the iron in cyclopentadienyliron di

carbonyl sulfonyls should be readily detected by a shift

to lower values in the S-0 stretching frequencies in the

infrared spectra of the complexes. However, before any

shift could be studied, it was necessary to identify the

S-0 stretching frequencies. *

Organic sulfones are recorded (76, 77) as having

strong absorption bands in the 1120-1160 cm ^ and 1300- — 1 1350 cm ranges of the infrared. These bands are gener

ally assigned to the symmetric and asymmetric S02 stretch—

ing vibrations. All sulfones also have a medium to strong

intensity band at 54-5-610 cm-1 which is due to the S02

scissoring vibration. Saturated sulfones have a second Figure 6 A comparison of the NMR spectra of cyclopenta

dienyl (benzyl)dicar"bonyliron(II) and cyclo-

pentadienyl( "benzylsulfonyl)dicarbonyliron(II).

117 5.31

Fe — CHj -C 6Hs

2.80 in CDCI

T.M.S. 7.23

4 .90 CO

F e - S O ,- C H .

CO in CDCI

T.M.S. 2.42 5.61 V 118

2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 X 119 medium to strong intensity band at 495-525 cm-1 which has been assigned to a wagging vibration.

The substitution of one alkyl (aryl) group by a halo

gen in a sulfone would be expected to result in a shift of

both characteristic bands due to symmetric and asymmetric

stretching towards higher frequencies. Bellamy (76) re

ports that the range is, indeed, shifted upward for the

sulfonyl chlorides to 1340-1370 cm”1 and 1166-1185 cm-1. (See Table 8 )

Recalling that coordinated sulfur dioxide complexes

give strong bands in the 1350-1000 cm”1 region of the

spectrum (See Table 1), it seemed reasonable to expect

that coordinated sulfonyls could absorb in this region as well. Therefore, the entire region from 1370 to 1000 cm”1

in the infrared spectra of the sulfonyl derivatives was

examined carefully. If the spectra of 7i-C5 H5 5*6(00)2 CH3

and n-C5 H5 Pe(C0)2 S02 GH3 are compared (See Figure 9) it is

readily apparent that two strong bands occur (at 1057 and

1208 cm”1) in the spectrum of the latter which are not

present in the spectrum of the methyl derivative. These

two bands are also absent from the spectrum of Tt-CgHgFe-

(CO)2 SCH3 (78 ), which should exhibit essentially the same

strong absorptions as the sulfonyl spectrum, minus those

due to S-0 vibrations. (See Table 9) Thus, strong in

tensity bands in the 1045-1060 cm”1 and 1180-1210 cm 1 120

lA H F 8

Infrared SO Stretching Frequencies of Some Q» Sulfonyl Compounds

Stretching Frequencies, cm 1 Compound Symmetric Asymmetric

CH3S 02CH3 b 1157 1511 C6H5S0aC6H5 b 1155 1307 CHsCe^SOaCs^CHsh 1155 1319

CH3SO2CI ° 1175 1370 G6H5SQ2CI C 1185 13^0 CH3 C6 H4 S0 2 C1 c 1166 13 66

TT-C 5 HsFe(C0)2 S02 CH3 1057 1208

7 r-C5 H 5 Fe(C0) 2 S02 C2 H 5 10^9 1180

TT-C5 H 5 Fe(C0)2 S02 C 6 H 5 1050 1197 ir-C 5 H5Fe (C0 )2 S 0 2 C 6 H 4 CH 3 10it-5 1200

■T-CsHsFe(C0)2 S02 CH 2 C 6 H 5 1050 1187,1181

£r-C5 H5Fe (CO)sJ 2 S02 (CS2 ) 3 1055 1188 jy-CsHsFe (00)212(302)2(0112)5 1052 1187

9/ CHC13 solution unless otherwise stated. b CCI 4 solution See reference (77) C C6Hs solution See reference (76 ) 121 regions have been assigned as the S02 symmetric and

asymmetric stretching frequencies, respectively, for the

iron sulfonyl complexes. It is interesting to note that

Collman (73) reports the S-0 stretching frequencies of a new iridium complex, Ir(CO) [P(C6 H5 )3] 2 (S02 CH3 )Cl2 (to be

discussed later), to be 1240, 1220, and 1060 cm-1, in

good agreement with the assignments made in this study.

It is difficult to assign bands due to a scissoring

or wagging vibration because of the presence of medium-

strong intensity cyclopentadienyl and phenyl absorptions

between 495 and 750 cm”1 . Figure 7 shows two additional

new bands in the infrared spectrum of 7t-C5 H5 Fe(C0) 2 S02 - -1 -1 CHj : one at 753 cm and another at 531 cm . Other

sulfonyl derivatives have some additional bands in that

portion of the spectrum. For example, the benzylsulfonyl

compound gives a strong intensity band at 610 cm” 1 and a

medium intensity band at 522 cm” 1 which do not appear in

the spectrum of the benzyl derivative. But the sulfonyl

also has absorptions at 574 and 558 cm” 1 which are not

found with tc-C5 H5 Fe(C0)2 C6 H5 . The dinuclear propylene

sulfonyl derivatives are equally as complex in the lower

regions of the spectrum. Therefore, no definite assign

ments have been made for these two vibrations.

Once the S02 stretching frequencies have been identi

fied, it becomes obvious that they are considerably lower Figure 7. A comparison of the infrared spectra of

Tt-Cj H5 Fe(CO)2 CHj and tu-C5 H5 Fe ( CO )2 S02 CH3 .

122 Percent Tranemieelon o ro

3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Wovenumber in cm 124-

TABLE 9

Comparison of Infrared Absorption Frequencies, cm""'*' of C5H5Fe(CO)2CH3, C5H5Fe(CO)2S02CH3, and C5H5Fe(CO)2SCH3

CsH5Fe(C0)2CH3 3 C5H5Fe(C0)2S02CH3 b C5H5Fe (co)2sch3 c

C-H 3050 (vw) 3170 (vw) 3060 (vw,br) 2972 (m) 3091 (m,br) 3010 (vw,br) 2900 (m) 3050 (m,br) 2920 (ww) 2816 (vw) 2987 (vw) 2860 (ww) 2810 (w)

C-0 2018 (vs) 2058 (vs) 2032 (s) 1963 (vs) 2009 (vs) 1985(s) c-c 1438 (w) 1480 (m) 1420 (m) 1425 (w) 1432 (m) 1310 (w) 1424 (m,br) 1412 (m,br)

S-0 1208 (vs) 1057 (vs) other 1178 (m) 1298 (m) 1004 (w) peaks 1015 (w) 940 (m) 988 (w,br) 1010 (w) 850 (m) 947 (w) 837 (m) 753 (s) 845 (w) 800 (vw) 711 (m) 835 (vw) 695 (w) 617 (s) 642 (s) 579 (s) 599 (s) 560 (s) 575 (s) 531 (s) 515 (vw) 500 (w) 471 .(vw) 461 (w)

In w = weak s = strong bIn CH Cl vw = very weak vs = very strong 2 2 vvw = very very weak br = broad cKBr See reference (78) m = medium 125 than the frequencies found for organic sulfones or for coordinated sulfur dioxide. The lower values indicate that there has been a decrease in the sulfur-to-oxygen bond order. It is not difficult to envisage how the lowering of bond order arises, since HMR data indicate the possibility of some m-character in the iron-sulfur bond. Any increase in double bonding between the metal and sulfur would be accompanied by a decrease in double bond character between oxygen and sulfur.

The metal carbonyl stretching frequencies of the iron sulfonyl complexes should also be sensitive to any it-bonding between the metal and sulfur. As already noted, for mation of a x-bond would most likely be accomplished be tween filled orbitals of iron and empty orbitals of sulfur.

However, the antibonding x-orbitals of carbon monoxide and the d orbitals of sulfur have the same symmetry. (74)

Therefore, the -S02R moiety and CO will be competing for the appropriate iron orbitals. This competition should result in less %•-bonding between iron and CO (a lowering in the order of the M-C bond) and thus a shift of the car bonyl stretching frequencies to higher values in the infra red. Table 10 compares the stretching frequencies of

7i—Cj H5 Fe(C0)2 R complexes.

Two facts are clear from Table 10. First, the number of C—0 bands and the very strong intensities are consistent 126 with the dicarbonyl structure already assigned.^ Second,

the carbonyl stretching frequencies for the sulfonyl de rivatives are 30-40 cm”^ higher than those for the corr

esponding alkyl and aryl complexes (5 7)» indicating that

there is some 7i-character in the sulfur-metal bond. In

fact, the CO stretching frequencies for the sulfonyl de rivatives are very similar to those of 7t-C5 H5 Fe(C0)2 CN

(59). The sulfonyl group in these complexes, then, must be comparable in k -bonding ability to cyanide, a very good ic-bonder. (74)

TABLE 10

Infrared GO Stretching Frequencies of tc-C5 H5 FeCC0)2 R Complexes3,

R = cm”'*' (all very strong) < V C 2018, 1963 2010, 1950 2 0 2 0 , I960 OBfOfB, 2009, 1951 06 0*0 % 2 1 1 2 , 1963 C1T 2060, 2020 S02 CB3 2 0 5 8, 2009 SO2 C2 H5 2061, 2010 SOyCfiHj 2060, 2013 S02 CHg C6 H5 2060, 2010 S02 Cg CH3 2060, 2012

3In CHCl. unless otherwise stated ^ ee re^erence (6 8) °In C6 Hfi See reference (59)

^The absence of any C-0 bands in the 1450-1800 cm""^ spectral region eliminates the possibility that the products are acyl complexes. An interesting reflection of the energy of the Fe-S bond appears in the color of the sulfonyl derivatives.

Whereas 7i-C5 Hj Fe(CO)2 Cl and tc-C5 Hj Fe(CO)2 Br are red in color (59)» ti-G5 Hj Fe(C0)2 S02 R compounds are all yellow, indicating that the sulfonyls absorb at higher energies in the visible spectrum. The cyano derivative is also yellow. (59)

Ultraviolet irradiation reactions. The original purpose in irradiating the sulfonyl derivatives with ultraviolet light was to determine whether S02 or GO would be given off in a reaction similar to the decarbonylation of acyl derivatives. (7) The only new com pound recovered from the irradiation reaction was ferro cene, regardless of whether the methyl-, benzyl-, or phenylsulfonyl complex was used. Considerable amounts of unreacted sulfonyl derivative as well as an insoluble brown decomposition product were also recovered. Gas was evolved during the course of the reaction (ca 95 ml./

0.005 mole) but the volume collected in a gas burette was considerably less than that expected if all CO and

S02 are lost from the iron sulfonyl molecules (ca. 350 ml.).

Since no carbonyl bands were found in the infrared spec

trum of the brown decomposition product, it is believed

that CO has, indeed, been given completely off. Never

theless, the amount of gas collected is still small com- 128 pared to what should he given off if all the CO is evolved.

Increased stability of the metal-sulfur bond due to

7t-bonding may render loss of S02 more difficult than first anticipated. On the other hand, decreased 71-bonding be tween iron and carbon monoxide would result in a weaker

M-CO bond. The M-CO bond may be the first to break under ultraviolet irradiation, giving evolution of one or two

CO molecules and an unstable iron complex which then de composes to ferrocene and an insoluble brown residue. It is very likely that S02 is present in this residue. One strong band, which may be due to S-0 stretching vibration, appears at 1234 cm"*’1' in the infrared spectrum of the solid.

Once carbon monoxide is lost, however, the infrared spec trum could be significantly different for the -S02R group and a definite assignment becomes difficult.

Heating sulfonyl derivatives. Iridium sulfonyl com plexes of the type represented in Equation 10 have been reported this year by Collman and co-workers. (73) They found that S02 could be removed by heating the aryl (but not the alkyl) sulfonyl compounds in toluene at 110°C.

It therefore seemed reasonable to expect that the iron arylsulfonyl derivatives could react analogously under

similar conditions. However, heating tc-C5 H5 Pe(C0)2 S02-

C6H5 at 110°C. under nitrogen in toluene gave no reaction. 129

Cl Cl

toluene 110°C.

Cl Cl

X = H, CH, CSS) 0 * G6H5 Because of the completely different metal systems in volved here, this result is not as surprising as it might first appear. One of the primary differences between the two kinds of molecules is the charge on the metal. Iron(II), with the lower oxidation state, will be better stabilized by formation of a x-bond between the metal and sulfur than will iridium(III). Back-donation from the metal to sulfur may result in a stronger M-S bond in the case of iron, thus making cleavage of that linkage more difficult. But, again, the differences between these two types of molecules make any contrast or comparison of this kind difficult,

A toluene solution of cyclopentadienyl(phenylsulfonyl)dicarbonyliron(II) was also refluxed at 110°C. under carbon monoxide. No gas was evolved and there was no ex change of S02 for CO. The sulfonyl derivative was re covered in essentially 1 0 0 % yield.

Reaction with halogens. Cyclopentadienyl(methylsulfonyl)dicarbonyliron(II) was reacted with chlorine to 130 determine which bond (or bonds), if any, would be cleaved.

Large quantities of gas were liberated during the course of the reaction and a viscous oil formed. In order to distinguish whether CO or S02 was evolved, the gas was bubbled through a saturated solution of barium chloride.

Carbon monoxide does not react with barium chloride whereas sulfur dioxide reacts to form a white precipitate of BaSOj .

The first portion of gas liberated did not give a precipitate with BaC^ . But, later in the reaction, BaS03 suddenly began to form. Since no evidence for the formation of a carbonyl or sulfonyl compound was found after bubb ling had ceased, it has been concluded that first carbon monoxide and then S02 were evolved. Some of the gas may have been CHjCl, but there is no proof at this time that it was formed in the reaction.

Distillation of the viscous oil gave small yields of

CjI^Cl, obviously formed from dissociated cyclopentadienyl group. When the benzyl- and phenylsulfonyl derivatives were reacted in the same way with C^ , formation of gas and C5H5 Cl were again observed. However, both of these

compounds also produced small amounts of chlorobenzene.

Although no benzyl chloride was ever detected as a pro

duct in the benzylsulfonyl reaction, it is believed that

C6 % Cl was formed by reaction of chlorine with either the 131 -CH^ C6 H5 or -CgH5 group. Since the reaction was carried out in benzene solution, CgHjCl could conceivably have been formed by interaction of C12 and C6 Hj in the presence of iron. But the absence of any chlorobenzene in the pro ducts of the reaction using te-C5 H5 5*6 (00)2 S02 CH3 supports the former route.

Actually, decomposition of these derivatives is not too unexpected. Reaction of tc-C5 H5 Pe(C0)2 Cl with chlorine in benzene solution under the same conditions resulted in gas evolution and formation of a viscous oil which con tained CjHgCl. (No CgHsCl was produced in this reaction.)

It is doubtful, however, that cyclopentadienyliron dicar bonyl chloride'*' was first formed as an intermediate from it— C5 H5 I'e(C0)2 S02 GBj and C]^ . This step would require

either formation of a sulfonyl chloride or evolution of

S02 before CO. No sulfonyl chlorides were recovered after

the reactions, and it has already been shown that CO was

the first gas evolved. Also, initial formation of the

chloride would change the color of the benzene solution

from yellow to red, the characteristic color of 7i-C5 H5 Fe-

(C0)2 C1, and no color change was observed.

The same reaction was also tried with bromine in

^The sodium salt of benzene sulfinic acid does not lose S02 on reaction with Cl2 under these conditions. 132 hopes that a weaker oxidizing agent would give a different result. Bromine, unfortunately reacted in the same manner, causing loss of S02 and CO and completely decomposing the

iron complex.

The failure of "bromine to react as desired led to the use of iodine, a still weaker oxidizing agent. (75) (The

oxidation potential of I2 is 0.555 volt, whereas for Br2 ,

E§98=1.07 volt.) Even on heating, iodine gave no reaction with the cyclopentadienyliron dicarbonyl sulfonyl deri vatives. Possibly thiocyanogen, with an oxidizing power

intermediate between Br2 and I2 (E§98=0.77 volt), would react without causing decomposition of the sulfonyl com

pound, if it should react at all.

Reaction with sodium borohydride. Sulfonyl deriva

tives of cyclopentadienyliron dicarbonyl were reacted with

sodium borohydride in an attempt to reduce the -S02R

moiety to a sulfoxide (-S0R) or sulfide (-SR) linkage.

Even at 0°C., however, decomposition occurred to give an

insoluble brown compound. Examination of the infrared

spectrum of this solid showed that all carbon monoxide

and sulfur dioxide as well as all groups containing hydro

gen had been lost. It has been observed in the course of

this study that all cyclopentadienyliron dicarbonyl de

rivatives are unstable in basic media and decompose to a

brown, insoluble solid (like the one noted above) which 133 is believed to be iron(III)' oxide. Therefore, milder conditions than those used in this investigation should be employed to effect reduction, if possible.

Investigation of the molybdenum derivative. it-C« St Mo COO)* S0» OB* . Since eye1opentadienyl(alkyl)tricarbonylmolybdenum(II) complexes participate in CO insertion in much the same way as their iron counterparts, it was of interest to see whether this chemical analogy extends also to S02 inser tion.

Preparation of ti-Ck HgMoCCO)* S0» CKt . Two methods were used to prepare eye1opentadienyl(methylsulfonyl)tricar- bony lmolybdenum(II). First, it-Cj H5Mo(CO)3 CHj was diss*- olved in liquid sulfur dioxide, giving insertion of S02 between the metal and the methyl group.

k-C3H5Mo(CO)3 CH3 + S02 — --0-G-^ x-CgHg Mo(CO)3 S02 CHg (67)

83% Some decomposition to molybdenum metal occurred during the course of this reaction. Since the sulfonyl derivative dissolves in liquid S02 without decomposition, the parent methyl compound is obviously the species which undergoes reduction.

Cyclopentadienyl (methyl) tricarbonylmolybdenum( II) adds to sulfur dioxide at about the same rate as the methyl and ethyl derivatives of iron. Therefore, the mechanism of “insertion” may be the same: nucleophilic attack of S02 accompanied by migration of the methyl group.

The second method used to prepare the sulfonyl de rivative utilized the reaction of eye 1 opent adienyl - molybdenum tricarbonyl hydride with methanesulfonyl chloride*

tc-CjHjMoCCKOjH + CBsSOaCl ) x-Cj Hj Mo (00)3 S02 CH^ + 1% (6 8 ) 71-C5 HjMoCCCOj Cl + [tc-Cj HgMoCCO^J 2

Some interesting comparisons with the iron system can be made at- this point. Under the same conditions as those for the reaction between the sodium salt of cyclopentadienyliron dicarbonyl and methane sulfonyl chloride, no 71-C5 1%Mo(CO)3 S02 CHj resulted from u-C5 H5 -

Mo(CO)3 Na and C1S02 CHj . Only the chloride, 11-C5H5M 0- (C0)5C1, was produced in 93% yield* Also, reaction between PS02 CHj and tc-Cj H5 Mo(CO)3 Nai yielded only the dimer, whereas the iron salt reacted to give some sul fonyl derivative as well as the dimer. Finally, al though sulfonyl complexes were prepared from the iron carbonyl dimer and sulfonyl chlorides, the molybdenum dimer gave no reaction. This may be a reflection of the strength of the metal-metal bond in the molybdenum 135 compound.

It may be that the first reaction between the sodium

salt and methanesulfonyl halides leads to formation of tc-C5 Hj M o (CO)3 X and NaS02 CHj . If this is the case, it

appears from the products recovered that eye1opentadienyl- molybdenum halides do not react very rapidly with NaS02 CHj •

The stable chloride is recovered in large yields. If any

x-C5 Hj Mo(CO)3 F is formed, it is very likely an unstable

species which undergoes decomposition to the dimer, the

only product in the reaction with FS02CHj, and/or an F-

containing compound.

Physical properties of x-CgKtMoCCO)* S0» CH« . The

methylsulfonyl derivative of cyclopentadienylmolybdenum

tricarbonyl is a golden, crystalline substance with a

sharp decomposition point (See Table 5)» ®be solid de

composes to a black material after standing for several

weeks in air; slight decomposition in chloroform solution

takes place after only 15 minutes at 27°C. in air. The

complex is readily soluble in benzene, chloroform, di-

chloromethane, alcohols, acetonitrile, tetrahydrofuran,

acetone, and water, but it is insoluble in non-polar

solvents such as pentane, hexane, carbon disulfide, and

cyclohexane. Nuclear magnetic resonance spectra show

sharp proton signals indicating that the compound is dia

magnetic. 1 3 6

Nuclear magnetic resonance studies. Table 11 shows the methyl and cyclopentadienyl proton signals in the NMR spectrum of tc-Cj HjMoCOO^R. As in the spectrum of the iron-methylsulfonyl derivative, addition of S02 has re sulted in deshielding of both -CHj and tc-C5 %• Because of the remarkable similarity of the nuclear magnetic reso nance spectra and the physical properties of the iron and molybdenum complexes, the sulfonyl linkage assigned to

iron sulfonyl derivatives is assumed to be present in the; case of tc-Oj % Mo(CO)3 S02 CH, .

TABLE 11

Proton Magnetic Resonance Spectra of 71-C5 HjMoCCO^ R

R = Chemical shift /t Relative intensity Assignment

0% a 4.73 5 7C—O5 He 9.66 3 -0% S02 C% 4.06 5 H-O5 He 6.71 3 -0%

^ee reference (6 8 )

The result of insertion of S02 between molybdenum

and the methyl group is evidenced in the shift of the sig

nal for the methyl protons from 9*66 (6 8 ) to 6.71^* A

certain amount of u-bonding between the sulfur and metal,

pulling electron density away from the ring, must account

for the deshielding of the 71-05% group protons.

Infrared spectroscopic studies. Sulfonyl and carbonyl 137 stretching frequencies, again, were used to test the theory that sulfur is participating in Tt-bonding with the metal. Recalling that an Mo-S bond would result in the lowering of S-0 stretching frequencies and a correspond ing increase in 0-0 stretching frequencies in the infra red, the 1300-1000 cm”1 and 2100-1900 cm 1 regions of the

spectrum were examined to locate the proper bands. The

S-0 stretching frequencies for x-CjHjMoCCO)*S02 CH5 (See

Appendix I for complete spectrum) were assigned to strong bands at 1223 and 1055 cm”1 . These bands are not present

in the spectrum of ti-Cj Hj M o ^ O ^ CH^ . (57) The frequen

cies correspond closely to those found for the iron sul

fonyl complexes, indicating that the assumption of struc

tural similarity between iron and molybdenum sulfonyls is

valid. The low values support the idea of Tt-bonding be

tween molybdenum and sulfur.

Carbonyl stretching frequencies for the molybdenum

sulfonyl derivative (2058 and 1975 (broad) cm”1) are

shifted to values 30-40 cm”1 higher than those of the

methyl complex (2023, 1934-, 1904- (shoulder) cm”1), (68 )

Thus Tt-bonding between the metal and carbon monoxide has

been reduced, probably because of competition with sulfur

for the filled d orbitals of molybdenum.

In summary, infrared studies, when coupled with RMR

studies, have afforded a good picture of the structure of 138 and bonding in tc-C^HjMoCCO^SC^ CHj . First, the number and intensity of the CO bands in the infrared spectrum of this molecule are consistent with a tricarbonyl assign ment. The absence of any CO bands in the 1800-1450 cm”'*' region of the spectrum precludes the presence of an acetyl moiety. Secondly, the values; for the methyl hydrogens in the proton magnetic resonance: spectrum of the complex show that S02 has been inserted between the metal and the

-CHj group. Finally, the remarkable similarity between the S-0 and C-0 stretching frequencies: and the NMR spectra

of the iron and molybdenum methylsulfonyl derivatives in dicates that the bonding of the sulfonyl group is the same

in each case. Therefore, structure I in Figure 7 has been assigned to the molybdenum complex. Formation of an Mo-S bond with some x-character is considered likely.

Inveatigation of the Mercury

Sulfonyl Derivatives

The dialkyl and diaryl mercury(II) system was chosen

for study for several reasons. Having ascertained that

S02 insertion will proceed with some transition metals, it

was of interest to see whether the reaction could be ex

tended to include representative metals. The R2Hg system

offers an excellent opportunity to test whether or not the

presence of 00 in the molecule is necessary for S02 inser

tion. The effect on the insertion reaction (if any) of 139 changing the coordination number of the metal can also be studied. Finally, it was hoped that more concrete infor mation concerning the assignment of S-0 stretching frequen cies could be obtained from the infrared spectra of the mercury derivatives.

Preparation of the compounds. Four sulfur dioxide complexes of mercury were prepared by dissolving dialkyl

(or diaryl) mercury(II) compounds in liquid sulfur dioxide and allowing them to react for several days.

BjjHg + S02 ----- > RS02 HgR (69)

R=-C2Hj , -C6H5 ,

An additional product of the empirical formula

(C2 H5 Hg)2 S02 was formed when diethyl mercury was used.

The irregular yield of this compound (on one occasion none of it was produced) indicates: that it is a by-product rather than a major sulfonyl. Also, (C2 H5 Hg)2'S02 cannot be prepared by dissolving C2 S02 HgC2 1% in excess liquid sulfur dioxide. Similar dinuclear species were not ob tained using diphenyl or dibenzyl mercury.

There is some evidence that a free radical mechanism may be involved in the reactions of K^Hg and S02,. When

(OgHjOE^^Hg is dissolved in liquid sulfur dioxide, the

solution becomes bright orange. Diethyl mercury forms a yellow solution. The intense color may be due to formation of free radical species RHg* and .R. If this is the case,

S02 could react with either radical to give several poss ible products: RS02R, RS02 HgR, or (RHg)2S02 . A mechanism of this type accounts for the formation of C02^ H g ) ^ S 02 and C2 % S02>HgC2 H5 but it leaves several points unex plained. Firsi, it offers no explanation why the diinu- clear species is formed only with the ethyl complex.

Secondly, no organic sulfones were recovered from the re actions, although this mechanism would predict their formation* Finally, these reactions do proceed in the absence of light, though much more slowly than in the light of a tungsten lamp. For example, diethyl mercury required two weeks to react with liquid S02 to give 10% yield when all light was excluded* In normal laboratory light, a 42% yield was obtained after seven days* The fact that some sulfonyl was produced without exposure to light may mean that more than one mechanism is being utilized.

Rates of reaction for the individual mercury com pounds are difficult to compare because of the difference in solubilities of the parent complexes in liquid sulfur dioxide. Diethyl mercury is; almost immiscible in liquid

S02 at -40°C., a property which naturally retards re action. Diphenyl and dibenzyl mercury, on the other hand, are extremely soluble. In general, however, all the 141 mercury compounds react less rapidly than any of the iron or molybdenum alkyls and aryls.

Attempts to prepare the phenyl derivative by a metathetical reaction between C6 H5 HgCl and NaS02 C$ Hj were not successful. Sulfur dioxide was evolved during the course of the reaction and diphenyl mercury was formed.

Gg B| HgCl + NaS02;C6H5 ---- >(C6H5 )2Hg + S02 + NaCl (70)

A similar reaction was tried in 1905 by Peters. (40)

He observed evolution of S02 in the reaction of mercuric chloride and sulfinic acids at elevated temperatures. It was hoped that loss of S02 might be prevented by carrying out the reaction expressed in Equation (70) at very low temperatures. However, even at -78°C. only diphenyl mer cury was obtained.

Although Otto (39) reported the preparation of (C4 H5 - S02 )2 Hg by bubbling sulfur dioxide through a diphenyl mer cury melt, a disulfonyl product of this type was never found in this study.

Physical properties of the mercury derivatives.

Table 12 lists some physical properties of the mercury sulfonyl derivatives. They are all white, crystalline compounds with sharp melting or decomposition points.

The three mononuclear complexes are all moderately soluble

in solvents such as chloroform, dichloromethane, tetra- TA.BLE 12

9j Some Physical Properties of Mercury Sulfonyls

Mbl.wt. Compound Color m.pt.°C. Caled. Found Solubility

CeHsHgSOaCsHs white 105 419 446 These compounds are sol uble in CHCI3 , CH2C12 , CeHsCIfeHgSOaCHaCsHs white 95 447 495 THF, and liquid S02 . They are insoluble in water, C2HsHgS02C2H5 white 85(dec.) 325 273 alcohols, and CeH6 . __ b (C2H5Hg)2S02 white 195(dee.) 524 Sparingly soluble in liquid S02 ) insoluble in H20, CH3OH, CHCI3 , and GeHe»

Qi Prepared hy insertion of S02

Compound too insoluble to measure 2-trT 14-3 hydrofuran, and liquid sulfur dioxide. The dinuclear com pound, £C2HgHg)2 S02 , is insoluble in all common solvents, including alcohols and water; it is sparingly soluble in liquid sulfur dioxide.

Solid (C2 H^Hg)fcS02 appears to be indefinitely stable in air. Phenyl (phenylsulfonyl)mercury(II) is the most stable of the three other derivatives. It shows no signs of decomposition after several months of storage. Ethyl-

( ethy1 sulfony1 )mercury(II) becomes: dark after standing for two or three weeks, and solid C6 Hj CHa HgS02 CI^ Cg H5 decom poses to elemental mercury and dibenzyl sulfone in a matter of hours at room temperature.

Dioxane solutions of the sulfonyl compounds have been heated at 100°C. for several hours under nitrogen without causing decomposition. On standing in air for 24- hours, however, solutions of all three of the sulfonyl deriva tives decompose slightly. It is interesting that solid benzyl (benzylsnlfonyl)mercury( II) decomposes so rapidly whereas solutions of the compound are relatively stable.

The proximity of all groups to one another in the crystal

lattice evidently facilitates decomposition. Sharp pro

ton signals in the NMR spectra of these compounds indi

cate that they are diamagnetic mercury(II) derivatives.

Nuclear magnetic resonance studies. Proton magnetic

resonance spectra of the mercury sulfonyl derivatives (EARLE 15 Q» Proton Magnetic Resonance Spectra of tfercury Derivatives, RHgR'

R s R 1 = Chemical shift, b Relative ares Assignment

) W 0 0 01 -302C6H5 1 . 87- 2.62 (m) - -C6H5 -ch2c 6h5 -so 2gh2c 6h5 2.17-2.97 (m) 10 -c 6h5 6.16 (s) 2 - s -ch2 - 7.01 (s) 2 - ch2 - -CH2CsH5b -so 2gh2c 6h5 2 . 20- 5.17 (m) 10 -c s h5 6.22 (s) 2 -s-c h 2 7.1 2 (s) 2 - ch2 - -C2Hs -S02C2Hs 7.0^-7.5l(q)(J=7cps) 2 -s-c h 2 7-53-8.05(q)(J-7cps) 2 - ch2 - 8.25-8.77'(m) d 6 -CHS -GsHs13 -S02G2Hs 7 .19-7 .6 6 (q)(j-6 cps) 2 - s - ch2 - 7.71-8.2i(q)(Js6 cps) 2 - ch2 - 8 .4 2 -8 .8 8(q) ' d 6 -ch3 -CH2C6Hs -ch2g6h5 2 .5 3 -2 .8 5 (m) 10 -c 6h5 7.60 (s) 4 -CH2- -C2Hs -C2Hs 7.98-8.51(qt) - -c2h5 Q/ In CDCI3 unless otherwise noted s = singlet In liquid S02 at -20°C. q = quartet clTeat m = multiple t See discussion qt = quartet superimposed on a triplet 145 were recorded in CDC13 at 25°C. and in liquid sulfur di oxide at -20°C. The results are given in Table 13. No

NMR data are available for one compound, (C2 ^5 Hg)2 S02 , because of its insufficient solubility.

Several points are at once apparent from the Table.

First, sulfur dioxide has evidently been inserted between one alkyl or aryl group and mercury. This is shown most clearly in the spectra of dibenzylmercury(II) and benzyl-

(benzylsulfonyl)mercnry(II). Not only have the signals been shifted to lower fields, but there is an indication of two different kinds of methylene protons as a result of addition to sulfur dioxide.

If the two methylene groups are non-equivalent, the

S02 must be located between the metal and one benzyl group, i.e., C$ Hj HgS02 CHg Cg . An assignment such as

this also explains the shift downfield. Protons belong

ing to the methylene group bonded to S02 would be signi

ficantly deshielded (6.16t) relative to those of the methylene group bonded directly to the metal (7 .10 t).

But the latter have also been deshielded compared to the CHj, hydrogens of the parent compound, (Cs Hj CHj, )2 Hg 07.60*3. The same downfield shift is observed for the reso

nance peak of the methylene protons in benzylmercuric ha

lides as compared to dibenzyl mercury. (79) The order 146 of chemical shifts in this system, however, is CgHgOHg-

Hgl (6.86*; Ah »0.74 )> Cg Hj CHg HgBr (6.89t;A* =0.71 )>

Cgl^CHaHgCl (6*93tJAi =*0.6? ). This result is the re verse of the order ejected on the basis of electro negativities alone. However, similar apparent reversals

of electronegativity effects have been found in proton

NMR studies involving the methyl proton resonance shifts

in ethyl halides (80, 81), in NMR studies involving 13 13 C directly attached to halogens as well as 0 one atom

removed from halogens (82), and in trimethylsilicon ha

lides. (83) It is probable that deshielding of methylene

hydrogens (belonging to the -CHg group bonded to Hg) which

occurs on sulfur dioxide insertion is due to formation of

an Hg-S ir-bond rather than to a purely inductive effect.

The NMR spectrum of the benzylsulfonyl derivative of

mercury supports a sulfur-bonded structure of this type.

Recalling that bonding through one oxygen would be ex

pected to give an AB splitting pattern for the methylene

protons in the SC^OHaCgHs group, the presence of two sharp

singlets in the methylene region of the spectrum can be

interpreted to indicate a sulfone linkage.

Nevertheless, there are two other possible structures

which could account for the observed spectrum. The first

is an oxygen-bonded species which exchanges so rapidly

that only a single, average value for the methylene hydro- 147 gens is observed.

Hg-q,,-?-OHj -R Hg-Qj^-CH, -E (71) ^!) HD The second possibility is: an extension of this ex

change reaction. Both oxygens of S02 could be bonded to

the metal in a chelate fashion. In this structure sulfur

would not be asymmetric and, thus, the methylene protons would be equivalent, giving only a single-line NMR spec

trum.

In view of the higher affinity of mercury for sulfur

than for oxygen (53 ), a sulfonyl-type linkage is the most

likely. A recent report by Bullock and Tuck (84) shows

that, the compound (NH* ^Hg^Oy;^ is sulfur-bonded; there

fore, there is little reason to expect RHgS02R derivatives

to bond other than through sulfur.

Although the proton magnetic resonance spectrum of

the ethylsulfonyl derivative is quite complicated, it can

also be rationalized to support a sulfur-bonded structure.

As: noted in Tshle 13» three sets of peaks appear in the

spectrum of the compound: two quartets and a "multiplet".

The quartets are obviously due to the methylene protons

but the "multiplet" requires further explanation. Making

the interpretation even more difficult is the fact that

the spectrum taken in liquid sulfur dioxide exhibits a

more complex "multiplet" than that recorded in CDCI3 . 148 Since C2 H5 HgS02 C2 1% has two non-equivalent ethyl groups, the expected spectrum should contain two quartets and two triplets. Prom the analysis of intensities of the signals and the spin-spin coupling values, it is believed that the protons of the two methyl groups are magnetically so similar that their triplet signals are superimposed on one another, giving the "multiplet" observed. (See Figure 8 )

There is a significant difference between the spectrum of C2 HgS02 C2 Hj recorded in CDClj and the one recorded in liquid S02 • The chemical shifts are not the same in each solvent (See Table 13). Also, as shown clearly in Figure 8 , the coupling constants differ: 3 = 7 cps in CDClj and 6 cps in liquid S02 . A similar solvent effect is evident upon examination of the proton magnetic resonance spectra of the benzylsnlfonyl derivative. The sharp singlets assigned to the methylene proton signals of Cg Hj CHg HgS02 CH*,C6

(See Table 13) occur at 6.16 and 7«01~t in CDCly , but atj

6.22 and 7.12 ^ in liquid S02 • These changes in the proton magnetic resonance spectra may result from solvation of the complexes by one or more molecules of S02 .

Nevertheless, the spectrum of the ethylsulfonyl de rivative in either solvent represents two sets of A^Bj patterns. (An A2 B3 spectrum is frequently found for ethyl compounds CH3 CE^ X, where X has nuclear spin equal to zero

(85).) A comparison of the "fc values for the two methylene n J'= 6 cps

J = 6cps

Assig nment

H i - s - c h 2- c h 3

□ n . CHj-CHj-Hg

■In liquid SO* ,-20°C.

In CDCI 25°C.

i + n

Figure 8. Proton magnetic sonanc e spectrare of the methyl protons in C2H5HgS02C2H5< 150 groups of C2 H5HgS02 02 H* with those for diethyl mercury

(See Table 13) shows that both sets of -CH^-hydrogens in the sulfonyl compound have been deshielded* As already noted in the case of the benzylsulfonyl derivative, the deshielding is likely due to formation of a metal-sulfur x-bond, if the compound is sulfur-bonded. The proton magnetic resonance spectrum of the ethylsulfonyl complex does not definitely prove that the -S02 C2 H5 moiety is not bonded through both oxygens in chelate fashion, nor does it discount the possibility of a rapid equilibrium be tween two oxygen-bonded structures. But;, as stated earlier, bonding through oxygen is considered unlikely.

Although the proton magnetic resonance spectrum of the phenylsulfonyl derivative cannot be used to clearly define the mode of attachment of the sulfonyl group in that compound, it is reasonable to expect that C6 H5 Hg-

S02 Cg H5 is: bonded the same as the benzyl- and ethylsul fonyl compounds.

Nothing definite can be said about the structure of

(C2 H5 Hg)2 S02 . The recent synthesis of C2 H5 HgSHgC2 H5 from (C2 H5 )2Hg and carbonyl sulfide (86 ) leads to specu lation that the two compounds may be similarly bonded with sulfur bridging the two ethylmercury groups. An

other possible structure, C2H5 Hg-HgS02.02H5 , utilizes a mercury—mercury bond. The lack of physical data on this 151 compound prohibits any specific structural assignment.

Proton magnetic resonance studies have also been helpful in qualitatively ascertaining whether S02 in sertion takes place at lower temperatures (-11 to -20°C.) or only at or above the boiling point of sulfur dioxide

C-10°C.). A sample of pure dibenzyl mercury was dissolved in liquid S02 and placed in the probe of the NMR spectro meter. The solution was maintained at -20°C. using a variable temperature control. The spectrum was scanned from 0 to 10 t at one minute intervals. During a period of 20 minutes, the intensities of the peaks due to di benzyl mercury decreased and those of the peaks corre sponding to the benzylsulfonyl derivative increased. This shows that the insertion reaction does proceed in liquid

S02 solution below -10°C. as well as at higher temperatures.

The experimental conditions employed here and the sharp quality of the NMR signals under these conditions indicate that formation of the sulfonyl while the sample is in the probe cannot be attributed to a free radical pro cess, mentioned earlier. Since essentially all light is excluded while the sample is suspended in the probe at

-20°C., generation of free radicals is very improbable.

If. any free radicals are present, however, a definite broadening of the NMR signals should be observed. The peaks due to both dibenzyl mercury and benzyl(benzyl- 152 sulfonyl)mercury were very sharp and! clearly defined.

Infrared spectroscopic studies. The infrared spectra of the mercury sulfonyl derivatives show that S-0 stretch ing frequencies are much lower than those of the iron and molybdenum compounds. A comparison of the spectra of

C$ Hj HgSC6 1% and C6 Hj HgS02 C6 H5 was used to make assignments listed in Table 14. As shown in Figure 9» there are two peaks in the 800-1300 cm”1 region of the spectrum of the sulfonyl compound which do not appear in the spectrum of

CgHgHgSCgHg (1058 and 847 cm*”1). These values are about

200 cm”1 lower than the assigned S-0 stretching frequen cies for 7t—C5 H5 Fe(00)2 S02 R.

At first glance, the low values for the S-0 stretch ing frequencies in mercury derivatives (See Table 15) might be interpreted to indicate bonding through oxygen.

Recent information concerning a new tin compound shows that this could be the case. Coilman and Slager (8 7 ) have prepared (CH,)3 SnS02 C6 H5 and report that this com pound is oxygen-bonded. The structural assignment is based on the presence of a band at 957 cm”1 in the infra red spectrum which is believed to be due to an Sn-0 stretching vibration.

(CH3 )3 SnOl + Cg H5 S02 Na --- > (0% )3 Sn-0-g-C6 H5 (72)

A compound was synthesized by the author from stoi- Figure 9. A comparison of the infrared spectra of

C6 H5 HgSCg H5 and C6 Hg HgSO*C6 H5 .

153 O - H g - S - O in

a Hg - S— ^

in K Br

J L J L 4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Wavenumber in cm-i 155

TABLE 14

A Comparison of the Infrared Absorption

Frequencies (cm*"1) of C5H5HgS02C5H5 and

C6H5HgSC6H5 3

C6H5HgS02C6H5 C6H5HgSC6H5

3076 (w) C-H 3068 (w) 3021 (w) 3058 (w) 3015 (vw)

1576 (w) c-c 1576 (s) 1479 (m) 1475 (s) 1463(sh) 1463 (w) 1438 (s) 1437 (m) 1390 (w) 1430 (s) 1390 (w)

1058 (vs) S-0 847 (vs)

1332 (vw) other 1333 (vw) 1307 (w) bands 1306 (w) 1186 (w,br) 1188 (w,br) 1092 (m) 1084 (m) 1026(sh) 1072 (w) 1005 (w) 1023 (s) 847 (vs) 1000 (w) 752 (s) 903 (w) 737 (s) 898 (sh) 701 (vs) 737 (s) 593 (s) 726 (vs) 529 (m) 693 (vs) 476 (w) 510 (sh) 456 (m) 482 (m) 477 (sh) 454 (m) a KBr p e lle ts w = weak vw = very weak s = strong vs = very strong m = medium br = broad sh = shoulder 156 chiometric amounts of (CHj )3 SnCl and C6 Hj S02 Na in freshly distilled THF at 27°C. The infrared spectrum (KBr) of the product of this reaction showed a strong-intensity band at 970 cm“^. The only other strong-intensity band

in the 1000 to 600 c m - '*' region occurred at 780 cm” ’1'.

No bands were present between 1 0 0 0 and 1100 cm”’1' and 800-

900 cm”’1', where the S-0 stretching frequencies of the mer

cury derivatives are found.

Table 15

Infrared S-0 Stretching Frequencies of RHgS02R a

S-0 stretching frequencies, c m ”’1’ R * Sym. Asym.

-CjkHj 1053 (s) 1156 (s,br) -OHgCgHj 879 Cs) 1052 (s> 840 (s) 1050 (s)

aNujol mulls s » strong br » broad

It would appear that the 1100-600 cm”'1' region of the

infrared spectra of the RHgS02R compounds is not compa

rable to that of the iron sulfonyl compounds nor of the

oxygen-bonded tin complex. Therefore, it is difficult to

assign a structure on the basis of infrared evidence alone.

Recalling that the two extreme structural possibilities

are a sulfonyl-type linkage and a system where the -S02R

moiety is attached to the metal through both oxygens in 1 5 7 chelate fashion, it is entirely possible that the actual

structure is somewhere between these two. The sulfonyl

group may be sulfur bonded but some interaction may also

exist between the oxygens and vacant orbitals on mercury.

This would result in a lowering of S-0 bond order and

lead to the frequencies observed. A structure of this

type would also be compatible with the NMH spectra of the

mercury derivatives.

The entire infrared spectra of these compounds and

of (OgHjHg^SOg are reported in Appendix I. No sulfonyl

stretching frequencies have been assigned for the poly-

nuclear compound because of the lack of information con

cerning its structure.

7c-Cb Hg Fe(OO), SnC(k R t )x and SO, When TC-C5H5 Pe(CO)2Sn(C6 H^ )3 had. been dissolved in

liquid sulfur dioxide and allowed to react for several

hours, usually no reaction took place. But on one

occasion, alumina chromatography separated a yellow-green

compound from the starting complex. Very little cx>uld be

done to characterize this compound because only a few

crystals were produced. An infrared spectrum was taken,

however. The absorption frequencies of the product are

compared with the absorption frequencies of 7E-C5H5 3?e(CO)2

S n ( C 6135)3 in Table 16. 158

TABLE 16 a “1 Infrared Absorption Frequencies of Iron-Tin Complexes (cm )

-n--C5H5Fe(CO)2Sn(C6H5)3 JT-C5H5F e(CO)2Sn(C6H5)3 + S02

3057 (w) C-H 3081 (w) 2930 (vw) 2945 (vw) 2915 (w)

2365 (vw) 2368 (w)

1995 (vs) C-0 2076 (s ) 1935 (vs,b r) 2001 (vs)

1573 (w) C-C 1467 (vw) 1476 (w) 1449 (w) 1422 (m) 1430 (vw) 1410 (w) 1415 (w) 1381 (vw) 1377 (w)

S-0? 1190 (s) 1031 (s)

1300 (vw) other 1231 (vw) 1256 (vw) bands 1080 (m) 1181 (vw) 1018 (w) 1066 (m) 849 (w) 1019 (w) 748 (w) 994 (m) 698 (m) 870 (vw) 687 (m) 853 (vw) 611 (m) 840 (m) 584 (m) 830 (w) 568 (s) 725 (s) 556 (s) 700 (s) 635 (s) 604 (s) 587 (vs) 520 (w) 458 (vw) 448 (m) 436 (vw)

aKBr p e lle ts w - weak vw = very weak s = strong vs = very strong m = medium br = broad Two facts become immediately evident from the Table.

First, two new strong bands appear at 1 1 9 0 and 1031 cm”1 which are not present in the spectrum of the parent com pound. These are both similar in frequency and intensity to the S-0 stretching absorptions of the iron and molyb denum sulfonyl derivatives, which are found in the 104-5-

1223 cm”1 region of the infrared spectrum. Therefore, S02 is probably contained in some form in the product.

Second, the carbonyl stretching frequencies of the pro duct are considerably higher than those of the parent. Re calling that addition of S02 to iron and molybdenum alkyl and aryl complexes has resulted in a shift of the carbonyl

stretching frequencies to higher values, it is reasonable

to suggest that sulfur dioxide is bonded in some form to

either iron, tin, or both in the product. The absence of

any bands in the 920-980 cm 1 region of the infrared spec

trum (this region is generally assigned to an S n - 0 stretch

ing vibration (88 )) precludes an oxygen-bonded tin species. The S02 could insert between tin and one or more

phenyl groups or it could insert between the two metals,

much in the same way SnOil^ inserts between the two iron

atoms of the cyclopentadienyliron dicarbonyl dimer. (38 )

It is doubtful that insertion between tin and the phenyl

group would have the pronounced effect on the carbonyl

stretching frequencies observed in this case. Therefore, 160 it is more likely that insertion between the two metals took place. Of course, this cannot be confirmed until analyses and more physical data have been obtained.

Tc-Cg Hg Fe (CO), SifOH, )« and SO,

Since the insertion reaction of sulfur dioxide with compounds containing a,metal-carbon bond was so success ful, insertion between the metal-silicon bond of tc-C5 Hj -

Pe(CO)2 Si(0H3 )j was tried. Small amounts of a red oil were collected as the only product of the reaction. This compound was extremely unstable in air, making physical studies very difficult. Samples decomposed to a brown solid before an infrared spectrum could be recorded. For this reascn no evidence was obtained to show whether the red substance was an insertion product.

Investigation of the

Manganese System

The carbon monoxide insertion reactions of alkyl- and arylmanganese pentacarbonyls have been well character ized in recent years. (3» 18, 24) Apparently, R migrates quite easily in these compounds. (28) The recent report by Strohmeier and Guttenberger (49) of synthesis of a

7u—C5 Hj Mn(C0)2 S02 derivative indicates that manganese can form stable sulfur dioxide complexes. Therefore, it was of interest to see whether the manganese pentacarbonyl alkyls and aryls could react with sulfur dioxide to give complexes such as Kn(CO\ (C0R)S02 or Mn(C0)^S02R. Before insertion of S02 was attempted, however, it was first necessary to demonstrate: that a compound of this type is stable.

{Che first method used to prepare a manganese sulfonyl derivative involved the reaction between NaMn(CO)5 and benzenesulfonyl chloride. The product of this reaction was a yellow powder which is not monomeric in chloroform solution. Osmometry indicates a molecular weight of over

1000 , whereas the molecular weight of the expected pro duct, 06 Hj S02Mn(C0)5 , is 331. Elemental analyses show that sulfur is present in the molecule, but also confirm the fact that the product is not benzenesulfonylpenta- carbonylmanganese(l), or any dimeric species such as

Mn^CCO^CSOgCgHj )2 . The infrared spectrum is of little help in identifying this compound. Table 17 records the infrared absorption frequencies of derivatives formed by reacting benzene-, methane-, and ethanesulfonyl chlorides with NaMn(C0)5 . (It should be noted here that reaction with C1S02 CHj and CISO^ C2 gives yellow powders which have the same properties as the product formed when C1S02 -

CgHj was used, i.e., molecular weight of about 1000 and apparent elemental composition which does not correspond to any stoichiometrically reasonable product.) 1 6 2

TABLE 17

Infrared Absorption Frequencies For Compounds Prepared from NaMn(CO)^

and RS02Cla

R = ~CH3 R = -C2H5 R = -C6H5

3012 (vw) 3010 (s) 3080 (vw) 2358 (vw) 2346 (vw) 3021 (vw) 2206 (vw) 2200 (vw) 2106 (m) 2068 (sh) 2103 (w) 2046 (vs) 2050 (vs) 2038 (vs) 1981 (vs) 1992 (s) 1980 (s) 1939 (vs) 1953 (vs) 1948 (vs) 1485 (vw) 1308 (vw) 1457 (w) 1456 (m) 1128 (m) 1135 (m) 1189 (vw) 1011 (m) 1055 (m) 1126 (m) 953 (vw) 1010 (m) 1097 (s) 1075 (m) 1035 (s) 1019 (s) vw = very weak 1000 (s) vs = very strong 715 (s) sh = shoulder 698 (m) w = weak 680 (sh) s = strong 669 (w) m = medium 658 (sh) 632 (w) 600 (s) 539 (m) 437 (w) a CHClg solu tion A monosubstituted six-coordinate pentacarbonyl man ganese complex of the type Mn(CO)5X would have C^v symme try. Group theory considerations predict four carbonyl stretching frequencies, namely 2 A1 + E + . One of the

A, and the E vibration are expected to be both infrared and Raman active \ the remaining A, and the B., mode should be Raman active only, if the metal is in the plane of four carbonyls. However, a slight distortion of the man ganese from the plane of four equatorial CO’s activates the second A, mode, which then gives rise to a weak ab sorption in the infrared spectrum. (90 ) By comparison with the spectra of the pentacarbonyl halide complexes

(8 9 ), the relative intensities? of these infrared active bands are expected to be weak (A1 (2)), strong (E), and medium (A, (l)1) . The relative intensities of the carbonyl bands for the three compounds noted in Table 17 are weak, very strong, strong, and strong.

In view of the local C symmetry about sulfur in the s -S02R group (This is the highest symmetry possible here.), molecular C^ symmetry is not expected for Mn(C0)5 S02R.

Recently, Wilford and Stone C90, 91) have shown that for manganese and rhenium pentacarbonyl complexes, M(C0 )5 L

(where L is an organic ligand and the L-M group lacks axial symmetry), all four fundamental modes noted above can become infrared active and the degeneracy of the E 164 mode may also be removed. For example, the infrared

spectrum of C$H5Mn(CO)5 in hexane has five C-0 bands: 2114 cm”1 weak (A1 (2)>, 2055 cm”1 weak (Bi)» 2021 cm”1

strong (35(2 )), 2010 cm”1 strong (E(l)>, and 2002 cm”1

strong (JLjC'l));. Other unsymmetrical ligands give rise

to a weak B1 peak but do not split the E mode at all. (91)

The complex spectra observed in the case of the manganese

"sulfonyl" derivatives are not at all similar to the spec

tra of the type noted above, however.

It is more likely that the compounds are not pure when spectra are being taken. Several observations made

in the course of this study indicate that this is the case.

First, solid samples of the yellow, powdery products which

had at one time been dissolved in chloroform could not be

completely redissolved in the same solvent. Some fraction

of the sample always failed to go back into solution. This

behavior would seem to indicate that polymerization is

taking place in solution or on recrystallization. Secondly,

successive recrystallizations; of the products resulted in

subtle changes in the infrared spectra* For example, the

medium-intensity band at 2106 cm”1 in the spectrum of the

product obtained from reaction with benzenesulfonyl chlo-

ide los* intensity while the strong band at 1939 cm”1

gained intensity. Furthermore, the intensity of a medium

band at 1126 cm”1 was observed to decrease with repeated 165 recrystallization.

Decomposition, isomerization and/or polymerization may be occurring in solution, thereby making character ization of the products difficult. A proton magnetic resonance spectrum of the compound recovered from the re action of NaMn(CO)5 and C1S02 OH3 showed a sharp singlet at

7«84-£. Although this would ordinarily indicate the pre

sence of only one methyl group-containing compound in so

lution, the datum must be interpreted with caution in view

of the other evidence already discussed.

It is of interest to note that a product prepared

from Mn(CO)5Br and NaS02 C6 H5 exhibits behavior identical with that of the "benzenesulfonyl11 derivative mentioned

above. It also has the same infrared spectrum as the

latter derivative. (92) When NaMn(CO)5 was reacted with PS02 OBg, another yellow

product was obtained but this compound has an infrared spec

trum quite different from that of the compound recovered

from reaction with C1S02 CHg. The carbonyl stretching fre

quency region of the spectrum contained three bands:

2121 cm”1 (vw), 2055 cm_1 (vs>, and 194-0 cm”1 (vs, broad).

No further attempts were made to characterize this complex.

Elemental analyses of the compound did reveal that it is

not a fluoride derivative, however.

One attempt was made to prepare (GHjS02 )Mn(G0)5 by 166

insertion of sulfur dioxide with, methylmanganese penta carbonyl. The product of this reaction was a yellow pow der which was soluble in chloroform and insoluble in pentane. The infrared carbonyl bands for this compound are

completely different from those of the other two "methane-

sulfonyl" derivatives. The bands occur at 2098 cm”1 (w),

2055 cm”^(vs), and 1962 cm"’1 (w, broad). Although this

compound has not been identified, its infrared spectrum

shows that it is neither dimanganese decacarbonyl nor a

pentacarbonyl species, Mn(C0)5 X.

Unfortunately, an acute shortage of M^COO)^ made

a detailed study of this system an impossibility. Cer

tainly, new compounds have been prepared from these re

actions, but the composition and structure of the pro

ducts is still unresolved.

Investigation of the

Palladium System

Another compound which gave intriguing results upon

reaction with sulfur dioxide was trans-PdfOHs )2 [jP(C6 Hg )£j 2 .

This complex was investigated for several reasons. First,

Chatt (15) has shown that CO insertion proceeds with di

alky lbisphosphinepalladium(XI) compounds and therefore it

seemed possible that insertion of S02 could also take

place. Second, palladium has an empty dg2 orbital which

should be readily available for nucleophilic attack by 1 67 S02 . It is of interest to know what effect the presence of this vacant orbital will have on reaction with S02 and what product or products will be formed. Sulfur dioxide may be inserted between palladium and one or both of the methyl groups; it may be substituted for a phosphine either as a monodentate ligand or as a bridging group be tween two metal atoms; or, it may simply add to the square planar molecule in an axial position to form PdCCHj)2-

[p(C6 H5 ),_] 2 S02 or PdCCHj )2 [P(C6 E; )3] 2 (S02 )2 . Finally, the absence of any carbon monoxide in this system offers an opportunity to determine whether reaction with S02 can proceed without CO being present as a ligand.

The product of the reaction of trans-Pd(C%)2-

jjP(Cg H5 )3J 2 and liquid S02 is a yellow crystalline com pound which decomposes sharply at 105°G* It is soluble in chloroform, lower molecular weight alcohols, and ace tone, but insoluble in water, pentane, and benzene. The solid appears to be stable in air, showing no signs of decomposition after two weeks; solutions of the compound are less stable, with decomposition occurring after one hour.

Elemental analyses indicate that the product is neither Pd(S02 CH, )2 [P(C6 H5 )3] 2 nor PdCCI^ )(S02 CH, )-

[PCCgHj)£f 2 , although sulfur is definitely present in

the complex. The infrared spectrum (KBr) of the product 168 has bands at 3079 (vw), 2986 (vw), 1482 (m), 1433 (m),

1238 (m, broad), 1192 (sh), 1167 (sh), 1120 (m), 1110 (m),

1073 (m), 1028 (w), 1008 (w), 974 (vw), 924 (vw), 855 (vw),

749 (vs), 714 (sh), 693 (s), 665 (vw), 647 (in), 617 (w,- broad), 538 (sh);, 521 (s), and 509 cm”^ (sh). No bands other than those present in the spectrum of trans-

PdCl2 fp(C6 H5 )3J 2 appear in the S-0 stretching frequency

(1200-700 cm”^) of the spectrum of the product, although elemental analyses prove that the latter is not the dichloro complex. A proton magnetic resonance spectrum shows a broad multiplet at 1,83-2.75 (relative area 39) which has been assigned to the phenyl protons of triphenylphosphine, and two very crowded singlets, one at 7*18

(relative area 2) and another at 7.26 'c (relative area 4).

The singlets overlap each other somewhat. These relative intensities correspond to no product of reasonable stoi chiometry. Obviously, both the IR and NMR data impart little useful information as to the nature of the compound, except to indicate that it is none of the expected pro ducts. Since the parent compound, trans-Pd(CH, )2 Qp(C6H5 )£] 2 , was never prepared in its pure state in this study, the difficulties encountered in preparing a sulfonyl deriva tive may result from impurities or the unstable nature of the dimethyl complex. (58) 1 6 9

Attempts to prepare a sulfonyl compound of palladium(II) "by reacting trans-PdCl, |~P(Hu ),] 2 and NaS02 C6 Hg were not successful. The two reagents did not react at all in N,N-dimethylformamide at 27°C. It has been sug gested (93 ) that the failure of these compounds to react may be due to the strong trans directing ability of the

-S02R group. If this is the case, a cis complex such as

Pd(bipy)Cl2 might react with the sodium salt of a sulfinic

acid to give mono- or diisulfonyl derivatives.

Investigation of the

Titanium System

Like the palladium(II) system, (m-Cj ^ )Ti(CHg )2 has

an empty low-energy orbital on the metal which should be

readily available for nucleophilic attack by S02 „ Also,

any insertion reaction of dimethy1tit anocene with S02 can

be studied in the absence of carbon monoxide as a ligand.

Since the results of reaction of the palladium compound

were inconclusive, it was hoped that the titanium system

would provide some- evidence as to the possible role of 00

in the S02! insertion reaction and the effect of the empty

orbital on titanium in the synthesis of new compounds.

Dimethyltitanocene was reacted with liquid sulfur

dioxide to give various red-orange products. The products

were crystallized with difficulty because of a tendency on

the part of all of them to form viscous oils. Because of 1 7 0 the lack of reproducibility of the experiments and the apparent loss of cyclopentadiene by the products, the ti tanium compounds have not been characterized. Elemental analyses do indicate that sulfur is present in the com pounds, however, confirming that some reaction did take place with sulfur dioxide.

Titsnocene diichloride was reacted with NaS02 C6 H5 to give a viscous red oil, similar to the ones mentioned above. On standing, the oil evolved cyclopentadiene. The product was not investigated further.

Investigation of the Acetyl

Derivatives. 7t-C« EU FeCCOXCOCH, )R

Cyclopentadienyl(methyl)dicarbonyliron(II) was re acted with several nucleophiles, other than S02 and 00,

ligands. When it had been demonstrated that carbon mon

oxide insertion (or perhaps; methyl migration onto a car

bonyl group) does proceed, it; was of interest to qualita

tively measure the effect of different nucleophiles on the

rate of the insertion reaction and to compare these obser

vations with S02 work done on the same system.

Preparation of the compounds. Acetyl derivatives of

cyclopentadienyliron carbonyl were prepared by refluxing

a tetrahydrofuran solution of te-Cj H5 Pe(00)2 CH3 and a phos

phite or phosphine at 6 5 °0 . for 48 hours. 171

7i-C5H5 I,e(CO)2 OH3 + m 5 --- ) U-C5H5 Fe(CO)(COCH, )ER3 (73) ca 100% R = -C6 H5 , - C k Hg , -0C6 H5 , -0 C*

The same reaction, when carried out in diethyl ether at 34°C. for the same length of time, only gave a 21% yield with tri-n-butylphosphine and a 50% yield with triphenylphosphine. Unreacted starting materials were re covered in good yields because only a small amount of decomposition takes place in these reactions under the con ditions employed.

Qualitatively, the rates of reaction of K-K^HgFe-

(C0)2 CH3 with phosphines in tetrahydrofuran were about the same as the rates with phosphites. Addition of ex cess ligand seemed to increase the rate of the reaction somewhat. Whereas a 1:1 mole ration of 7t-C5 Fe(C0)2 CH3 and tri-n-butylphosphine required 48 hours to give essen tially complete conversion to the acetyl compound (in

THE), a three-fold excess of the phosphine reduced neces sary reaction time to about 30 hours. The rate of re action also appears to depend on the solvent. After refluxing a hexane solution of Tt-C5 B5 Fe(C0)2 CBj and triphenylphosphine at 67°C. for one week, only unreacted starting materials were recovered from the reaction mix

ture .

These observations support a mechanism similar to 1 7 2 the one suggested by Mawby, Basolo, and Pearson (18) for the reaction of methylmanganese pentacarbonyl and a va riety of nucleophiles, L, to give acetyl derivatives,

(CHjCO)Mn(CO)*L. When the solvent is capable of coordi nation (THE, ether), a solvent-assisted methyl migration may take place first, followed by rapid entry of the nu cleophile , the latter step gaining importance as the li gand concentration increases.

Still, the possibility of an Sjj2 mechanism involving direct nucleophilic attack by the ligand on iron, accompa nied by migration of the methyl group onto an adjacent carbonyl, as opposed to the solvent-assisted mechanism, cannot be discounted. Experiments using several other ligands also support this mechanism. Diethyl sulfide,

£-toluidine, and |>-chloroaniline were refluxed with cyclopentadienyl(methyl)dicarbonyliron(II) in THE for 48 hours set 65°C. It the end of this time no detectable reaction had taken place.1

These three ligands are all weak bases and poor tu- bonders (95) and their failure to cause migration may be due to these properties. For example, it is possible that

1It should be noted here that, if the reaction proceeds by an S^l mechanism whereby methyl migration to a car bonyl group takes place first, these ligands should also give acetyl products. The apparent role of sol vent in these reactions also makes an S„1 mechanism unlikely. 173 there is a certain level of basicity which must be achieved before nucleophilic attack on the metal can proceed, Also, stable products may result only when the ligand is capable of forming a it-bond with iron.

It is difficult to assess the role of basicity in this problem because ir-C5 Hg Fe(CO)z CH3 is very unstable in strongly basic media. Reaction with pyridine, for example, resulted in the decomposition of the carbonyl complex in a matter of hours. The ability to ir-hond appears to be important in the reaction, however. In this study the only nucleophiles which have successfully caused methyl migration have been good x-bonders: phosphites, phosphines, and sulfur dioxide. By comparison, the reaction with

CBj Mn(CO)5 and different nucleophiles show only a modest dependence on the properties of the nucleophile. Good

71-bonders such as phosphines, phosphites, and carbon mon oxide, as well a® amines, which do not participate in

7C-bonding, all effect migration.

Physical properties of the acetyl derivatives. The

triphenylphosphine, tri-n>butylphosphine, and triphenyl— phosphite derivatives of cyclopentadienyl(acetyl)iron

carbonyl are crystalline solids whereas the tri—n-butyl-

phosphite compound is a liquid at room temperature.

Phosphine complexes were of a deeper orange color than

the phosphites, the latter being yellow-orange. All the TABLE 18

Some Physical Properties of the Acetyl Derivatives of CsH5Fe(0 0 )20%

Mbl.wfc Compound Color m.pt.°C. Calcd. Found ..Solubility

C5H5Fe(CO)(C0CH3 )P(C6H5 )3 orange 145 kjl All these compounds are soluble in CHC13, CH2C12 , C5H5Fe (CO) (COCH3 )P (C^g )3 orange 35-37 280 305 hexane, pentane, C6H6, and acetone. They are yellow- C5H5Fe(CO)(C0CH3 )P(0C6HS )3 502 I»81 insoluble in H20 and orange 65 lower alcohols. yellow- a __ h CsHsFe(CO)(COCH3 )p(OC4H9 )3 kh-2 orange

Si Liquid at room temperature

^ Not determined 175 solids have sharp melting points and are monomeric in chloroform. (See Table 18) In chloroform or benzene solutions, the acetyl compounds decompose in a matter of minutes to brown solids which have no carbonyl bands in their infrared spectra. Liquid 7t-C5 H5 Fe(CO) (OOCH3 )- PCOC* Hg)3 is equally unstable in air, decomposing to a brown solid. The crystalline derivatives are much more stable in the solid state, showing no signs of decom position after two weeks in air.

Solvents in which the^, acetyl derivatives are very soluble include chloroform, dichloromethane, benzene, acetone, and tetrahydrofuran. The complexes are moder ately soluble in pentane and hexane and insoluble in lower alcohols and water.

Nuclear magnetic resonance spectra of the products show sharp signals, indicating diamagnetic iron(II) complexes.

Nuclear magnetic resonance studies. The proton magnetic resonance signals for the acetyl compounds are listed in Table 19. Positions of the methyl hydrogen resonances indicate a deshielding effect of the acetyl carbonyl. Oyclopentadienyl(methyl)dicarbonyliron(II) shows a sharp peak at 9 *8 9 ^: for the methyl protons, a value about 2.4h higher than for the acetyl derivatives.

The carbonyl group apparently does not deshield the methyl 1 7 6

TABLE 19

Proton Magnetic Resonance Spectra of TT-C^H^FefCOjtCOCHgJPRg

R elative - PR3 = Chemical shift, £ Intensities Assignment

P(C6H5)3 2.41 (m) 15 C6H5 5.38 (s) 5 C5H5 7.48 (s) 3 ch3

P(CH2CH2CH2CH3)3 5.33 (s) 5 C5H5 7.25 (s) 3 CH3 8.02-9.21 (m) 27 (rv-but) p(0C6h5 )3 2.54 (m) 15 C6H5 5.68 (s) 5 c 5h5 7.32 (s) 3 ch3

P(0CH2CH2CH2CH3)3 5.33 (s) 5 C5H5 b 5.82-6.25 (q) 6 o-ch2 7 .4 3 (s) 3 ch3 8.08-9.17 (m) 21 (-ch2-ch2-ch 3) aIn CDC13 ^Two triplets partially superimposed (the signal due to the O-CH2 protons is s p lit in to a doublet by phosphorus and then each component is s p lit into a triplet by the nearest -CH2- protons.) s = singlet m = multiplet q = quartet 177

TABLE 20

Infrared CO Absorption Frequencies of TT-C^H^FeCCO^COCHgJPRg Complexes

cm- -*- pr3 = Terminal CO Acetyl CO p (c6h5)3 a 1920 (vs,br) 1598 (s)

P(CH2CH2CH2CH3)3 a 1916 (vs,br) 1590 (s) . p(oc6H5)3 a 1950 (vs,br) 1608 (vs)

P(0CH2CH2CH2CH3)3 b 1959 (vs,br) 1625 (vs) aCHCi3 solution vs = very strong s = strong boil - spectrum recorded between br = broad two KBr d iscs 178 protons quite as efficiently as S02 , however (See Table 6 ).

Sharp singlets due to the cyclopentadienyl hydrogens in

dicate the lack of coupling of the protons with the nu

clear spin of phosphorus.

Infrared spectroscopic studies. The presence of one

terminal and one ketonic CO band in the infrared spectra

of these complexes confirms the structural assignment of

tu-C5 H5 Fe(CO)(COCH3 )ER3 . The stretching frequencies for

the: two carbonyl groups are recorded in Table 20. The

The Derivatives n-Ck H* Fe(G0)9 CH» Ca K;

and Ti-Cg Hs Fe(CO)2 (£-C6 CHg )

Since the two compounds, tu-C5 H5 I*e(CO)2 Cg 1% and

TE-CjHjFeCCO^ (p-CgB^CHj ), were prepared for the first

time in the ccurse of this study, brief mention will be

made of their synthesis and properties.

Using the standard method of preparation of all

it-C5H5 Pe(CO)2R derivatives, the sodium salt of cyclo

pentadienyl iron dicarbonyl was reacted with an appropriate

alkyl (or aryl) halide.

7i—C5 H5 Pe(CO)2 Na + RX ---- > tc-C5 H5 Fe(C0)2 R + NaX (74)

When R= -CHg C6 H5 X=* Cl R= -Cg H* CH3 X= I

The benzyl derivative is a yellow-brown crystalline compound which, melts at 55-57°C» It is soluble in chloro form, benzene, pentane, and hexane. Although this compound decomposes in solution in a few hours, the solid is stable in air for several weeks, slowly decomposing to a brown material. The nuclear magnetic resonance spectrum of

7i-C5H5 Pe.('CjO)'j, CHg Cg H5 , which has been recorded in Table 6 , shows sharp peaks indicating the diamagnetic character of the compound.

Like n-C5 H5 Fe(CO)2 C5 H5 , the £-tolyl analog crystall izes with difficulty, reverting to an oil at the slightest pressure. It, too, is soluble in chloroform, benzene, pentane, and hexane\ it is insoluble in water. The oil is stable for a few hours in air. Solutions of the com pound show signs of decomposition to a brown solid in a few hours. The complete infrared spectra of these compounds are recorded in Appendix III. CONCLUSION

It has been demonstrated in this investigation that sulfur dioxide can he included in the rapidly growing group of unsaturated molecules which will undergo the so- called insertion reaction. Cyclopentadienyliron and

-molybdenum carbonyl alkyls and aryls react with liquid sulfur dioxide to give a new class of compounds: sulfonyl

(M-S02R) derivatives. As in the case of carbon monoxide insertion, the reaction with sulfur dioxide does not appear to depend on the presence of CO in the alkyl (or aryl) complex; this has been demonstrated for Hgl^ compounds

However, unlike the CO case, the reverse of the S02 inser tion reaction has not yet been effected for ic-C5 Hj Fe(CO)2- S02 C6 H5 or C6 H; CH*, SOg.HgCH;, C6 H5 .

Sulfonyl derivatives can also be synthesized by re

action between the anion of a cyclopentadienylmetal (where

the metal is either Fe(II) or Mo(II)) carbonyl and a sul

fonyl chloride, between cyclopentadienyliron-dicarbonyl

chloride and the sodium salt of a sulfinic acid, and be

tween the cyclopentadienyliron carbonyl dimer and a sul

fonyl chloride or fluoride.

The mechanism of sulfur dioxide insertion has not been

180 181 elucidated, but two paths appear most likely. First, a direct nucleophilic attack by S02 on the metal may be accompanied by a simultaneous migration of the alkyl or aryl group onto sulfur dioxide. Second, a solvent- assisted migration of the R group onto 00 (in the iron and molybdenum derivatives) followed by attack of S02 and subsequent migration of R onto sulfur may occur.

Detailed proton magnetic resonance and infrared spectroscopic studies of the iron and molybdenum compounds suggest that the M-S02R moiety is sulfur bonded in a sulfonyl-type linkage and that the ligand is a very good x-bonder. The structure of the mercury complexes is not clearly understood, but it is believed that bonding occurs through the sulfur with additional interaction between the oxygens and empty orbitals on mercury.

It is evident from this study that the sulfur dioxide insertion reactions with Mn(C0)5R and PdCCHj )2[P(C6H5 )3J 2 are much more complex than the analogous CO insertions and that further studies must be made on these systems. APPENDIX I

Infraredi Spectra? and Tabulated.

Absorption Frequencies of

Sulfonyl Derivativesa

aSpectra of 7t-C5 H5 Fe(CO)2 S02 GH3 and C5 H5 HgS02 C6 H5 appear on page 123 and page 154, respectively. V

Fe-S-CHoCH

in CHCI

0 0 4 0 0 3200 2800 2400 2000 1800 1600 1400 1200 1000 8006003600 40040 Wovenumber in cm 183 Tabulated Infrared Absorption Frequencies

for tc-C5 Hg Fe(CO)2 S02 0 H 2 C H 3

CHClg solution Nujol mull

OH 3120 (vw) 3005 0 0

0-0 2061 (vs) 2038 (vs) 2 0 1 0 (t s e ) 1989 (vs)

C-C 14-96 (a) 14-55 (m) 14-33 0 0 14-25 (w) 14-10 (w)

S-0 1180 (m) 1189 (s) 1050 (s) 1056 (vs) 1224 (w) 1205 (w) 1129 (w) 1072 (w) 927 (w) 871 (m) 851 (a) other 826 (vw) 704 (m) bands 670 (vw) 630 (vw) 611 (m) 589 (vw) 573 (a) 556 (s) 521 (aS 479 (vw) 487 (vw)

Abbreviations s = strong vs = very strong m a medium w = weak vw a very weak sh a shoulder br a broad CO

in CHCI

3600 3200 2800 24002000 1800 __1600 1400 1200 1000 8004000 600 400 Wovenumber in cm'

I—1 186

Tabulated Infrared Absorption Frequencies

for tc-05 H5 Fe(CO ) 2 S02 C6 H5

GHC1, solution Nujol mull C-H 3140 (vw) 3072 (vw) 3030 (m)

0-0 2060 (vs) 2065 (s) 2013 (vs) 2000 (vs) C-C 1480 (vw) 1445 (w) 1434 (vw) 1423 (vw)

S-0 1197 (m) 1195 (s) 1050 (s) 1042 (s-)

1223 (w) 1095 (s) 1023 (w) 850 (m) other 706 Cm) 693 (m) bands 615 (m) 586 Cs) 574 (s) 561 (m) 522 (w) 409 (vw) \

COI 0 I Fe-S-CH. CO 0

in CHCI3

4000 36003200 2800 2400 2000 1600 14001800 1200 1000 800 600 400 Wovenumber in cm'1 188

Tabulated Infrared Absorption Frequencies

for tc-C5 Hj Fe(CO ) 2 S02 GT^ C6 H5

CHClj solution Nujol mull

C-H 3110 (vw) 3072 (vw) 3030 (m)

C-0 2060 (vs) 2049 (vs) 2010 (vs) 2007 (vs) C-C 1497 (w) 1456 (w) 1440 (w.) 1425 (vw) 1413 (vw)

S-0 1187 (m) 1205 (s) 1181 (m) 1181 (s) 1050 (s) 1052 (s)

1298 (w) 1073 (vw) 873 (vw) 853 (w) other 6°0 (w) bands 610 (s) 590 (vw) 574 (s) 558 (a) 522 (m) 490 (vw) 500 (vw) 0 0 C 0 C I I I -Fe-S-CH2-CH2-CHZ Fei C 0 C 0 0 in CHCU

1 I 1 I 1 I I I I I___ I— 4000 3600 3200 2800 2400 2000 1800 1600 . 1400 1200 1000 800 600 400 Wovenumber in cm 189 Tabulated Infrared Absorption Frequencies

for tc-C5 Hj Fe(CO)^ S02 OH^ CHg CH,, Fe(CO)2^(7 t-C5 H5 )

CHC13 solution Nujol mull

C-H 3122 (vw) 3012 (m)

C-0 2060 (s) 2045 (vs) 2010 (vs) 1998- 1948 (s) 1989 (vs,br)

C-0 1458 (vw) 1437 (w) 1429 (vw) S-0 1188 (m) 1200 (s) 1053 (s.) 1052 (s)

1248 (w) 1009 (vw) 855 (w) 837 (w)

III c$ bands 618 (w) 594 (m) 577 0 0 561 (vw) 538 (vw) Fe -S-CHg - CHg- CH2- S - Fe

40003600 3200 2800 2400 2000 1800 1600 1200 1000 6001400 400800 Wovenumber in cm

t-* 192

Tabulated Infrared Absorption Frequencies for tt-05 H5 Fe (CO ) 2 S02 GHg CH5, CH* S02 Fe(CO ) 2 (ir-C5 Hj )

CHClj solution Nujol mull

0-H 3120 (w) 3098 (vw) 3013 (s) 2939 (vw)

C-0 2060 (vs) 2061 (vs) 2016 (vs) 2001 (vs)

C-C 1434 (m) 1422 (m) 1412 (w)

S-0 1187 (s) 1185 (a) 1052 (vs) 1049 (vs)

1243 (sh) 1226 (m,sh) 1177 (vw) 1022 (vw) 1005 (vw) 835 (s) 841 (vw) other 672 (s) bands 613 (a) 595 (a) 575 (vs) 557 (a) 330 (m) 517 (w) 497 (vw) 475 (vw) rV

C 0 0 in CHCI,

I I I I I I I I I I I L 4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Wovenumber in cm-1

1—1 vO V>1 Tabulate# Infrared Absorption Frequencies

for tc-C5 % Fe(CO) 2 (£-S02 C6 H* CH, )

OHCl, solution Nujol mull C-H 3130 (vw) 3019 (m) C-0 2060 (vs) 2062 (s) 2012 (vs) 2000 (vs)

C-C 1493 (w) 1460 0 0 1439 (vw) 1430 (vw)

S-0 1200 (m) 1195 (s) 1045 (s) 1191 (s) 1041 (vs) 1226 (w) 1097 (s) 1053 (sh) 1018 0 0 853 (w) 820 (w) (vw) other 715 677 (vw) bands 645 (s) 613 (m) 576 (vs) 560 (m) 517 (vw) 503 (vw) 479 (vw) \ / - Mo.

4000 3600 2800 24003200 2000 1800 1600 1400 1200 1000 800 600 400 Wovenumber in cm 195 1 9 6 Tabulated Infrared Absorption Frequencies

for tc-Cs Hj M o CCO^SCVCHj

CHClj solution Nujol mull

C-H 3120 (vw) 3025 (m)

C-0 2058 (vs) 2042 (vs) 1975 (vs,br) 1957- 1980 (vs,br)

C-C 1433 (w) 1426 (w) 1411 (w)

S-0 1223 (vs) 1190 (vs) 1055 (vs) 1051 (vs) 1306 (w) 1020 (w) 946 (w) 935 (vw) other 837 (w) 752 (vs,br) bands 672 (vs) 630 (w) 568 (w) 538 (m) 519 (s) 460 ^ 440 C -H g- S -C

in K Br

4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Wavenumber in cm 7 9 1 198 Tabulated Infrared Absorption Frequencies

for C6 H5 CH2 HgS02 ,0H2 C6 H5

KBr pellet Nujol mull

C-H 3098 (vw) 3068 (vw) 2910 (w)

C-C 1601 (m) 1500 (m) 1460 (m) 1430 (sh)

S-0 1055 (vs) 1052: (vs) 881 (s)‘ ‘ 879 (s)

1320 (w) 1220 (w,br) 1168 (w) 1131 (m) 1115 (sh) 1080 (s) other 1032 Csh) 1000 (sh) bands 852 (s) 826 (sh) 778 (sh) 769 (vs) 706 (vs) 625 (m) 601 (w) 529 (m) 476 (m) 458 (sh) 425 (w) CgHg~Hg — S ~ CgHg

in K Br

4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 6 0 0 4 0 0 Wavenumber in cm 199 200

Tabulated Infrared Absorption Frequencies

for H5 HgS02 C2 H5

KBr pellet Nujol mull

C-H 3029 (m) 3000 (sh) 2986 (m) 2890 (w)

0-0 1464 (m) 1422 (w) 1385 (w)

S-0 1138 (s) 1156 (vs) 1080 (s) 1053 (vs)

1305 (sh) 1276 (s) 1200 (vs) 957 (s,br) 780 (w) other 751 (a> 738 (s) bands 710 (m> 691 (m) 587 (s) 572 (s) 535 (s) 516 (s) 4000 3600 3200 2800 2400 2000 1800 1600 14001200 1000 800 600 400 Wovenumber in cm 201 202

Tabulated Infrared Absorption Frequencies

for (Cg ]3s Hg ) 2 S02

KBr pellet

C-H 2980 00 2960 (m) 2935 0 0 2926 (sb) 2875 Cm) C-C 1454 Cm) 1380 0 0 1251 Cs) 1194 Csb) 1185 Cm) 1111 (vs) 1 0 9 4 Cv s ) 1020 Cs) other 1000 other 940 Cvs,br) bands 872 00 " 801 Cs) 694 Cm) 673 Cw) 639 Cw) 620 Cw) 599 Cs) 585 Cm) 540 (vw) 530 (vw) 503 Cm) 460 Cm) APPENDIX II

Tabulated Infrared Absorption Frequencies

of Acetyl Derivatives

203 (Tabulated Infrared Absorption Frequencies

for TC-C5 H5 FeCCOXCOOH, )P(C 6 H 5 ) 3

CHCl, solution Nujol mull C-H 3072 (sh) 3068 (w) 3010 (m) 2979 (sh) 2908 (vw)

C—0 19201920 (vs,br)(vs,br) 1913 (vs,br)

C=0 15981598 (s,br) (s,br) 1600 (s)

C-C 1485 Cm) 1437 (s) 1421 (w) 1361 (vw) 1332 (m)

1195 (w) 1097 (s) 1073 (s) 1034 (vw) 1020 (w) 1002 (w) 921 (m,br) other 845 (w) bands 826 (m) 703 (s) 675 (vw) 615 Cm) 585 (m) 572 Cm) 532 (s) 512 (m) 500 (w) 458 (vw) 440 (vw) Abbreviations s = strong vs = very strong m = medium w a weak vw = very weak sh = shoulder br = broad Tabulated Infrared Absorption Frequencies

for it-C5 H5 Fe(C0)(C0CH* )PCOH2 CH2 ) 3

CHGlj solution Nujol mull

C-H 3010 (s) 2945 (sh) 2916 (vw) 2895 (w)

C-0 1915 (vs,br) 1916 (vs,br)

0=0 1591 (s,br) 1595 (s,br)

C-C 1469 (w) 1461 (w) 1382 (vw) 1328 (vw)

2350 (vw) 2191 (vw) 1218 (s) other 1099 (sh) bands 1076 (m) 1000 (w) 998 (m) Tabulated Infrared Absorption Frequencies

for tc-Oj H5 Fe(CO) (COCB5 >P(006 H5 ) 3

CHClj solution Nujol mull

C-H 3090 (w) 3020 (m) 2980 (sh) 2911 (vw)

C-0 1950 (vs,br) 1947 (vs,br)

C=0 1608 (vs> 1608 (vs)

C-C 1594 (vs) 1493 (vs) 1457 (w) 1440 (sh) 1421 (w) 1365 (vw) 1331 (m) 1292. (vw) 1200 (s) 1164 (s) 1074 (s) 1027 (s) other 1010 (w) bands 975 (vw) 925 (vs> 88? (vs) 8 3 2 ( s ); 725 (w,br) 693 (s) 671 (vw) 622 (m) 20 7 Tabulated Infrared Absorption Frequencies

for tc-C5 H5 Fe(CO) (COCH, )P(0CHs> CEfe CHj, OH, )3 liquid (spectrum taken between two KBr discs)

C-H 3140 (w) 2980 (s,br)

0-0 1959 (vs)br)

C aQ 1625 (vs,br)

C-0 1470 (s) 1436 (w) 1429 (vw) 1386 (m) 1327 (m)

1268 (w) 1240 (w) 1150 (sh) (s,br) other 1087 950 (s,br) bands 904 (s,br) 827 Cs) 798 (s) 731 (m) 620 Cs) 58 7 (vs) APPENDIX III

Tabulated Infrared Absorption Frequencies

for Tt-Cg H5 Fe(CO)2 C£-C6 H* 0H3 ) and TC-C5H5 Fe(CO)2 CB2 C6H5

208 tc-C5 H5 FeCCO)2 (£»C6 H* 0H3 ) oil (spectrum taken between two KBr discs)

C-H 2970 (sh) 2932 (m) 2860 (m)

C-0 2112 (vs) 1963 (vs)

C-C 1460 (s) 1380 (w)

2375 (w) 1188 (w) 1065 (vw) 1021 (w) other 1003 (w) 965 (vw) bands 895 (w) 847 (sh) 834 (w) 746 (m) 662 (m) 582 (m) 558 (m)

Abbreviat ions

s = strong vs » very strong m - medium w = weak vw = very weak sh = shoulder •rc«-C5 H5 Fe(CO) 2 CE^ C6 H5 in CHOlg Solution

C-H 3080 (vw) 3030 (vw) 2952 (vw)

C-0 2009 rvs) 1951 (vs) 1650 (vw)

C-C 1489 (m) 1453 (vw) 1432 (vw)

1225 (w) 835 (m) 702 (m) other 635 (m) 605 (sh) bands 590 (m) 569 (vw) 547 (vw) 513 (vw)

aThis band may be due to formation of some 71-O5 H5 Fe(CQ)2 (COCH*, C6 H5 ) in the cell. BIBLIOGRAPHY 212

(1) Heck, R.F., "Insertion Reactions of Metal Complexes," Preprint of the Lecture Presented at the Summer Symposium of the Division of Inorganic Chemistry of the American Chemical Society, University of Kansas, Lawrence, Kansas, June 21-24, 1964.

(2) Coffield, T.H., Kozikowski, J., and Closson, R.D., J. Org. Chem., 22, 498 (1957)*

(3) Coffield, T.H., Kozikowski, J., and Closson, R.D., Spec. Publ. Chem. Soc. No. 13, 126 (1959).

(4) Heck-, R.P., and Breslow, D.S., J. Am. Chem. Soc., 84, 2499 (1962).

(5) Heck, R.P., J. Am. Chem. Soc., 85, 651 (1963).

(6) Hieber, W., Yohler, 0., and Braun, G., Z. Natur- forsch., 13b, 192 (1958).

(7) King, R.B., andBisnette, M.B., J. Organometallic Chem., 2, 15-37 (1964).

(8) Hieber, W., Beck, W., and Linder, E., Z. Natur- forsch., 16b, 229 (1961).

(9) Hieber, W., and Linder, E., Chem. Ber., 95, 2042 (1962). (10) McClellan, W.R., J. Am. Chem. Soc., 83, 1598 (1961).

(11) Treichel, D.M., and Weiber, G., Presented at the 150th Meeting of the American Chemical Society, Atlantic City, New Jersey, 1965.

(12) Hieber, W., Braun, G., and Beck, W., Chem. Ber., 93, 901 (I960). (13) McCleverty, J.A., and Wilkinson, G., J. Chem. Soc., 1963, 4096.

(14) Heck, R.F., J. Am. Chem. Soc., 86, 2796 (1964).

(15) Booth, G. , and Chatt, J., Proc. Chem. Soc., 1961, 67.

(16) McAvoy, J., Moss, K.C., and Sharp, D.W.A., J. Chem. Soc., 1965, 1376.

(17) Keblys, K.A., and Pilbey, A.H., J. Am. Chem. Soc., 82, 4204 (I960). 213 (18) Mawby, R.J., Basolo, P., and Pearson, E.G., J. Am, Chem. Soc., 86, 3996 (1964).

(19) Bannister, W.D., Green, M . , and Haszeldine, R.N., Chem. Comm., 1963, 154.

(20) Bannister, W.D., Green, M., and Haszeldine, R.N., Proc. Chem. Soc., 1964, 370.

(21) Heck, R.P., and Breslow, D.S., J, Am. Chem. Soc., 82, 4438, (I960).

(22) Heck, R.P., and Breslow, D.S., J. Am. Chem. Soc., 84, 2499 (1962).

(23) Heck, R.P., J. Am. Chem. Soc., 85, 1220 (1963).

(24) Calderazzo, P., and Cotton, P.A., Inorg. Chem., 1, 30 (1962). (25) Basolo, P., and Pearson, R.G., "Mechanisms of Inorganic Reactions," John Wiley and Sons, Inc., New York, 1958, p„ 98ff.

(26) Pearson, R.G., and Lanier, R.D., J. Am. Chem. Soc., 86, 765 (1964). .

(27) Jones, T.P., Harris, W.E., and Wallace, W.J., Can. J. Chem., 39, 2371 (1961).

(28) Mawby, R.J., Basolo, P., and Pearson, R.G., J. Am. Chem. Soc., 86, 5043 (1964).

(29) Wilford, J.B., Treichel, P.M., and Stone, P.G.A., Proc. Chem. Soc., 1963, 218.

(30) Wilford, J.B., and Stone, P.G.A., Inorg. Chem., 4, 93, (1965).

(31) Beg, M.A.A., and Clark, H.C., Chem. and Ind., 1962, 140.

(32) Clark, H.C., and Tsai, J.H., Chem. Comm., 6, 111 (1965). "" C33) Nakamura, A., Mem. Inst. Sci. Res., Osaka Univ., 19, 81 a962);-cTAT, 59, 6786 ------

(34) Chiusoli, G.P., Angew. Chem., 72, 74 (I960). 214

(55) Greenfield, H., Sternberg,H.W., Priedel, R.A., Wotiz, J.A., Markby, R., and Wender, I,, J. Am. Chem. Soc,. Z§> 120 (1956). (56) Sly, W.G., J. Am. Chem. Soc,. 81, 18 (1959).

(57) Landgrebe, J.A., and Mathis, R . D . , J. Am. Chem. Soc.. 86, 524 (1964).

(58) Bbnati, F., and Wilkinson, G5., J. Chem. Soc., 1964, 3-79.

(59) Otto, R., J. Prakt. Chem., (2)1, 185 (1870).

(40) Peters, W., Chem. Ber., 58, 2567 (1905)*

(41) Prankland, E., and Lawrence, A., J. Chenu Soce, 55* 150 (1879). (42) Prankland, E. , and Lawrence, A., J. Chem. Soc., 5 5 * 244 (1879).

(45) Von Braun, J., and Weissbach, K., Chem. Ber., 6 5 * 2856 (1950). (44) Houlton, H.G., and Tartar, H.V., J. Am. Chem. Soc,* 60, 544 (1958).

(45) Baker, E . , and Sisler, H., J. Am. Chem. Soca, 75* 5195 (1955). (46) Glen, K . , and Breuel, W ., Z. anorg. alls. Chem., 255* 211 (1958). (47) Gleu, K., and Breuel, W., Z. anorg. alls. Chem., Z£» 345 (1965). (48) Braye, E . H . , and Hubei, W . , Angew. Chem.* 7 5 * 211 (1958).

(49) Strohmeier, W . , and Guttenberger, J.F., Chem. Ber.* 97, 1871 (1964). (50) Vaska, L., private communication to A. Wojcicki.

(51) Vogt, L*H., Jr., Katz, J.L., and Wiberly, S.E., Inorg. Chem., 4, 1157 (1965).

(52) Ibers, J.A., Presented at the 149th National Meeting of the American Chemical Society, Detroit, Michigan, 1965. 215

(53) Wilson, R.N., and Nixon, B.R,, J, Chem, Phys., 25, 175 (1956).

(54) Bibler, J.P., and Wo.lcicki, A., J* Am. Chem. Soc,, 86, 5051 (1964). ~

(55) Hallam. B.P., Mills, O.S., and Pauson, P,L,« J. Inorg., Nucl. Chem., 1, 313 (1955).

(56) Hayter, R.GE., Inorg. Chem,, 2, 1031 (1963).

(57) Piper, T.S., and Wilkinson, G., J. Inorg.- Nucl. Chem., 2, 104 (1956).

(58) Calvin, G*, and Coshes, G.E., J. Chem. Soc., 1960, 2008.

(59) Piper, T.S., and Wilkinson, G,, J. Inorg. Nucl. Chem., I, 165 (1954).

(60) King, R.E., Inorg. Chem., 2, 531 (1963).

(61) GOrish, R.D., J. A m 0 Chem. Soc., 84 , 2486 (1962).

(62Y King, RoB., and Shone, P.G.A., "Inorganic Synthesis," Vol. VII, McGraw-Hill Book Co., Inc., New York, New York, 1963* p. 198.

(63) Takagi, S., Tanaka, H 0, and Tsukatani, H., Bull. Inst. Chem. Research. Kyoto Univ., 27, 72 (l9$i).

(64) Sorum, C.H., "Introduction to Semimicro Qualitative Analysis," Prentice Hall, Inc., Englewood Cliffs, New Jersey, 1958, p. 160.

(65) Kleinman, M . , and Tapas, J.C., (to Velsicol Chemical Corp.) U.S.. Patent 2,904, 599, Sept. 15, 1959.

(66) Sharp, D.W.A., Proc. Chem. Soc., I960, 317.

(67) Coates, G.E., "Organometallic Chemistry," John Wiley and Sons, Inc., Second Edition, New York, I960, p. 285. (68) Davison, A., McCleverty, J.A., and Wilkinson, G., J.. Chem. Soc., 1963, 1133.

(69) Communication from Dr. G.V.D. Tiers to the Department of Chemistry, The Ohio State University. 216

(70) Jackman, L.M., “Applications of Nuclear Magnetic Resonance Spectroscopy in Organic Chemistry," Pergamon Press, New York, 1959, pp. 99-103.

(71) Waugh, J.S., and Cotton, P.A., J. Phys. Chem., 65, 562 (1961).

(72) Wilt, J.W., and Wagner, W.J., Chem. and Ind., 1964, 1389. (73) Collman, J.P., Kang, J.W., Roper, W.R., and Sears, C.T., Presented at the 2nd International Symposium on Organometallic Chemistry, Madison, Wisconsin, 1965.

(74) Zeiss, H., "Organometallic Chemistry," Reinhold Publishing Corporation, New York, I960, pp. 12-20.

(75) Moeller, T., "Inorganic Chemistry," John Wiley and Sons, Inc., New York, 1952, pp. 465-466.

(76) Bellamy, L.J., "The Infrared Spectra of Complex Molecules," (2nd Ed.), John Wiley and Sons, Inc., New York, 1958, pp. 360-363.

(77) Peairheller, W.R., Jr., and Katon, J.E., Spectrochim. Acta., 20, 1099 (1964).

(78) King, R.B., and Bisnette, M.B., Inorg. Chem., 4, 482 (1965).

(79) Rausch, M.D., and von Wazer, J.R., Inorg. Chem., 3, 761 (1965).

(80) Dailey, D.P., and Shoolery, N.J., J. Am. Chem. Soc., 77, 3977 (1955). (81) Allred, A.L., and Rochow, E.G., J. Am. Chem. Soc-., 79, 5361 (1957). (82) Lauterbur, P.C., "Determination of Organic Structures by Physical Mebhods," Vol. 2, P.O. Machod and W.D. Phillips, Ed., Academic Press, New York, 1962, p. 465.

(83) Schmidbaur, H., J. Am. Chem. Soc., 85, 2336 (1963).

(84) Bullock, J.I., and Tuck, D.G., J. Chem. Soc., 1965, 1877. “ 217 (85) Pople, J.A., "High-resolution Nuclear Magnetic Resonance," McGraw-Hill Book Company, Inc., New York, 1959, p. 154.

(86) Downs, R., unpublished results.

(87) Collman, J.P., and Slager, K., private communication to A. Wojcicki,

(88) Depaigne-Delay, A., Duval, C., and Lecomte, J., Bull, aoc. chim. Prance. 1946, 54.

(89) Gray, H.B., Billig, E., Wojcicki, A., and Parona, M.F., Can. J. Chem.. 1281 (1963).

(90) Wilford, J.B., and Stone, F.G.A., J. Organometallic Chem., 2;, 371 (1964);.

C 9 D Wilford, J»B., and Stone, F.G.A., Inorg. Chem., 4, 389 (1965). (92) Hartman, F.A., private communication.

(93) Gidden, R., private communication to A. Wojcicki.

(94) Angelici, R., Basolo, P., and Poe, A«, J. Am. Chem. Soc., 8£, 2215 C1963).