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University Microfilms International 300 N. ZEEB ROAD, ANN ARBOR, Ml 48106 18 BEDFORD ROW, LONDON WC1 R 4EJ, ENGLAND 8008782
POFFENBERGER, CRAIG ALAN
SYNTHESIS AND CHEMISTRY OF NOVEL SULFUR-OXIDE LIGANDS IN ORGANOMETALLIC COMPLEXES
The Ohio State University Ph.D. 1979
University Microfilms
in tern et lO nel 300 N. Zeeb Road, Ann Arbor, MI 48106 18 Bedford Row, London WCIR 4EJ, England SYNTHESIS AND CHEMISTRY OF NOVEL SULFUR-OXIDE
LIGANDS IN ORGANOMETALLIC 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
Craig Alan Poffenberger, B.S.
*****
The Ohio State University
1979
Reading Committee: Approved By
Dr. Andrew Wojcicki
Dr. Sheldon Shore Advisery Dr. Devon Meek Department of Chemistry ACKNOWLEDGEMENTS
I wish to express my sincere gratitude for the support and encouragement of my family and my wife, Kathy, throughout the course of this endeavor.
I am particularly indebted to Dr. Andrew Wojcicki for his advice and guidance during this research effort and in the preparation of this work.
I am grateful to my fellow graduate students and friends for their assistance in technical and non-technical concerns. I also wish to thank Vicki Faustini for typing this manuscript.
Finally, I wish to acknowledge the Chemistry Department of The
Ohio State University and the National Science Foundation for their financial support.
ii VITA
July 15, 1951...... Born - Rockford, Illinois
1973 ...... B.S., University of Illinois, Urbana, Illinois
1973-1979...... Teaching and Research Assistant, The Ohio State University, Columbus, Ohio
PUBLICATIONS
C. A. Poffenberger and A. Wojcicki, " Reactivity of the Alkylsulfite Ligand in u'-CsHsFeCCO)2 S (0)aOR. " Paper presented to the 1979 11th Central Regional Meeting of the American Chemical Society, Ohio State University, Columbus, Ohio, May 7-9, 1979.
C. A. Poffenberger and A. Wojcicki, " Alkylsulfito, Bisulfito, and Sulfito Complexes of r^-Cyclopentadienyldicarbonyliron(II)," J. Organometal. Chem., 165, C5(1979).
Craig A. Poffenberger, and Andrew Wojcicki, " Preparation and Properties of the Alkylsulfito Complexes (n^-C5H5)Fe(C0)2S(0)20R. " Paper presented to the 1978 Joint Central-Great Lakes Regional Meeting of the American Chemical Society, Butler University, Indianapolis, Indiana, May 24-26, 1978.
N. H. Tennent, S. R. Su, C. A. Poffenberger, and A. Wojcicki, " Synthesis of a Transition Metal Dithionite Complex, (n^-CsHs)(CO)2Fe-S(0)2-S(0)a-Fe(CO)2 (u^-CsHs), " J. Organometal. Chem., 102. C46(1975).
D. J. Sepelak, C. G. Pierpont, E. K. Barefield, J. T. Budz, and C. A. Poffenberger, " Organometallic Chemistry of the Carbon-Nitrogen Double Bond. 1. Nickel Complexes Prepared from Iminium Cations and the X-Ray Structure of [(C6Hs)3P]Ni[CH2N(CH3 )2 ]Cl,'* J. Am. Chem. Soc., 98, 6178(1976).
FIELDS OF STUDY
Major Field: Inorganic Chemistry, Professor Andrew Wojcicki iii TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS...... ii
VITA ...... iii
LIST OF T A B L E S...... v
LIST OF FIGURES...... vii
INTRODUCTION ...... 1
EXPERIMENTAL ...... 19
I. Reagents and Solvents...... 19
II. Instrumental and Physical Methods...... 22
III. General Experimental Procedures...... 23
IV. Literature Preparations...... 24
V. The Preparation, Characterization, and Reactions of Some New Sulfur-Oxide Ligands in Organo-Transition Metal Complexes ...... 25
RESULTS AND DISCUSSION ...... 86
I. Organo-Transition Metal-Dithionite Complexes .... 86
II. Organo-Transition Metal-Alkylsulfito Complexes . . . 113
III. Preparation of Transition Metal Complexes of the Ethyl Methanesulfinate Ligand...... 152
SUMMARY...... ,...... 160
CONCLUDING REMARKS ...... 163
APPENDIX...... 165
BIBLIOGRAPHY ...... 174
iv LIST OF TABLES
Table Page
1. Reactions of [r|®-CsHsFe(C0)2S0a]2 and RX...... 46
2. Infrared Spectra of the Transition Metal Dithionite Complexes, Diphenyl-«~disulfone, and Sodium Dithionite. . 87
3. Comparison of v(CO) and vCSOg) Absorptions for [n^-CsHsFeCCOaJaSOa and [n^-CsHsFeCCOaSOaJa...... 91
4. Ultraviolet-Visible Spectra of Selected Metal Carbonyl Dimers ...... 96
5. Ultraviolet-Visible Spectra of [n^-C5HsFe(C0)aS0a]2, [^^"CsHsFe(CO)a]aSOa» snd [Mn(CO)gSOa]a from 2700 Â to 6000 Â...... 108
6. Important Stretching Frequencies in r)^-CsH5Fe(C0)aS(0)a0R and Other Metal-Alkylsulf ito Complexes...... 116
7. Comparison of V(C0) and v(SOa) Absorptions for n^-CsHsFeCCOaSCOaCHa and n^-CsHsFeCCO) aS(0) aOCHa • • • • 118
8. NMR Spectra for n^-CsHsFe(CO)aS(0)aOR...... 119
9. NMR Spectra for MEn^-CgHsFe(CO)aSOa] ...... 137
10. Important Stretching Frequencies in [n^-CsHsFe(CO)a(SO(OCaHg)(OR))]PFe Complexes, r|^-CsHsFe(CO)aS(0)aOR Complexes, and OS(OCaHs)a...... 146
11. NMR Spectra of [r)^-C5HsFe(C0)a (SO(OCaHs ) (OR) ) ]PFe Complexes and 0S(0CHaCHg)2...... 148
12. Comparison of Important Stretching Frequencies of [n®-CsHsFe(C0)(L)(S0(0CaH5)(CH3))]PF6 Complexes and ri'-CsHsFe^CO) (L)S (O)aR Complexes...... 154
13. NMR Spectra for [n^-C5HsFe(C0)(L)(SO(OCaHs)(CHg))]PFe, n“-C5HsFe(C0)(L)S(0)a0R, and OS(OCaHs)(CHg) ...... 158
V LIST OF TABLES (contd.)
Figure Page
14. Major Mass Spectral Peaks for [n'-CsHsFeCCOjzSOajz. . . . 166
15. Major Mass Spectral Peaks for [Mn(CO)5 SO2 ]2 ...... 167
16. Major Mass Spectral Peaks for [Re(C0 )5 S0 2 ]2 ...... 168
17. Major Mass Spectral Peaks for Compound " A " ...... 169
18. Major Mass Spectral Peaks for (ri*-CsH5 )2Mo 2 S202 ...... 170
19. Major Mass Spectral Peaks for (ri*-C5H 5 )2W 2 S2 0 2 ...... 171
20. Major Mass Spectral Peaks for [ (n*-C5H 5 )3Fe3 (CO)^S]BFi, (n = 4 or 5 ) ...... 172
21. Major Mass Spectral Peaks for ri°-CsH5 Fe(C0 )2 S(0 )2 0 R . . . 173
VI LIST OF FIGURES
Figure Page
1. Apparatus for Photolysis of [M]g and SO2 at 20°C...... 29
2. Apparatus for Photolysis of [M]z and SO2 at -10°C .... 33
3. Apparatus for the Collection of Gases from Photolysis of [n*-C3HsW(C0 )3 ]2 and SO2 ...... 39
4. Titration Curve for the Neutralization of a 10 mL Aliquot of a Solution of 0.0331g of ri’*-C5HsFe(C0 )2 S(0 )2 0 H in 25 mL of H 2O with 0.04992 M N a O H ...... 78
5. Infrared Spectrum (Nujol) of [ri'-CsHsFe(CO) 2 8 0 2 1 2 in A) the 2100 to 1900 cm~^ Region and B) the 1300 to 900 cm“ ^ R e g i o n...... 8 8
6. Infrared Spectra (Nujol) of A) [Mn(C0)sS02]2 and B) [Re(CO)5 SO2 ]2 in the 1300 to 900 cm“ ^ Region ...... 98
7. Infrared Spectra of A) [Mn(C0 )sS0 2 ]2 in CH2 CI2 , B) Mn(CO)sBr in CHCI3 , and C) Mn(C0)5S(0)2CH2C6H5 in CHCI3 in the 2200-1900 cm"‘ R e g i o n ...... 101
8. Infrared spectrum (KBr) of ri*“CsHsFe(CO) 28(0)200113 in the 2100-1900 cm~^ and 1300-800 cm“ ^ Regions...... 117
9. NMR Spectrum of Tl®-C5H 5 Fe(C0 )2 8 (0 )a0 CH(CH3)2 in CDCI3 with TMS as Internal S t a n d a r d ...... 121
10. Infrared Spectrum (KBr) of r|“-C5HsFe(C0 )2 8 (0 )2 0 H in the 1300-700 cm“ ^ R e g i o n ...... 131
11. Infrared Spectrum (KBr) of Na[ri^-CsH5Fe(C0)2803] in the 1300 to 700 cm“ ^ Region...... 135
12. NMR Spectra of (CaHs)2NH2 tn®-CsH5Fe(CG)2SG3] A) Acetone-de and B) Acetone-de/DaG with TMS as Internal Standard ...... 138
vii LIST OF FIGURES (contd.)
Figure Page
13. NMR Spectrum of (CH3 )2NHa [n’-CsHsFeCCOaSOa] in CDCI3 with TMS as Internal Standard...... 142
14. Comparison of NMR Spectra of A) n“-CsHsFe(C0 )2 S(0 )a0 CH3 and B) [n’-CsHsFe(CO)2(SO(OCaH,)(OCH3))]PFe in CDCI3 with TMS as Internal Standard...... 149
15. Comparison of NMR Spectra of A) n*-C3H 5Fe(CO)2 S(0 )aOCaH5 and B) [n®-C5H5Fe(C0)2 (SO(OCaHs)a)]PFs in CDCla with TMS as Internal Standard...... 150
16. Comparisonof the Infrared Spectra (Nujol) of A) n®-C5H 5Fe(C0 )2 S(0 )aCH3 and B) [n®-CsH5Fe(C0 )a(S0 (0 C 2Hs)(CH3 ))]PF6 in the 2200 to 1900 cm“^ and 1250 to 800 cm“ ^ Regions...... 155
17. 'NMR Spectrum of [n®-C5HsFe(C0 )(PPha)(SO(OCaHs) (CH3))jPFe in Acetone-dg with TMS as Internal Standard...... 159
viii INTRODUCTION
The interaction of small, unsaturated molecules and transition metals is of paramount importance in many chemical processes (1).
Included among these processes are olefin polymerization, olefin
isomerization, alcohol and aldehyde formation in the hydroformylation
reaction, and nitrogen reduction (2,3). The transition metal plays an
important role in these processes by increasing the chemical reactivity of the small molecule such that it undergoes the desired transformation.
Sulfur dioxide, an example of a small, unsaturated molecule, has been observed to interact with metals in a variety of fashions. This diversity of behavior may be attributed to the amphoteric nature of SO2 .
The lone electron pair on sulfur or, infrequently, the lone electron pairs on the oxygen enable it to react as a Lewis base, but the readily available orbital on sulfur enables it to function as a Lewis acid (4).
Kubas (5) has recently presented criteria for the identification of the modes of SO2 coordination with metals. Combinations of the following properties have been found to be diagnostic of specific coordination geometries (5); the position of the antisymmetric and symmetric sulfur-oxygen stretching absorptions in the infrared spectrum of the M-SO2 adduct, the reversibility of SO2 coordination, and sulfate formation on treatment with oxygen. 2
In [RuC1 (S0 2 ) (NH3 )i,]Cl, the first M-SO2 complex to be determined
by X-ray crystallographic methods (6 ), the RU-SO2 unit is coplanar.
Although SO2 is a Lewis base in a coplanar coordination geometry, the
0 , 5 . 0 *
7 NH 0 Y Ru / H ^ N I Cl
1
Ru-S bond distance is shorter than the sum of the covalent radii
(Ru-S = 2.072 A, sum of covalent radii = 2.122 A), and this has been attributed to partial tt bonding, Ru ->■ S(7t), by overlap of the filled ruthenium d orbitals with the empty dp hybridized orbital on sulfur (6 ).
Similarly, the Mn-S bond distance in ri^-CsHsMn(0 0 ) 2 8 0 2 (Mn-S =
2.0371(5) A) is 0.3 A shorter than the sum of the covalent radii,and partial tt bonding was again postulated (7).
As a Lewis base, SO2 is usually irreversibly attached in coplanar complexes, but at least one presumably coplanar complex has been reported where SO2 is reversibly bound (8 ):
[M(C0 )5 S0 2 ]AsF6 N(CO),F • AsFs + SO2 (1)
M = Mn, Re
Coplanar M-SO2 complexes are unreactive toward oxygen, and the V(S0 2 ) stretching frequencies occur at higher energy than for other M-SO2 coordination geometries (5). 3
A different type of coordination geometry was identified when SO2
reacted as a Lewis acid with the basic metal complex, trans-IrCl(CO)(PPha)2 (9).
P h 3 R - t _ 7 C l / i r /
^ C ^ P P h 3
a = 31.6°
II
In IrCl(CO)(PPh3 )2 (S02) the Ir-S02 unit is non-planar and a pyramidal geometry is found at the sulfur. In II the Ir is slightly above the square plane by 0.21 Â, and the Ir-S distance is very long, 2.49 A (9).
This implies a weak Ir-S bond, and, in fact, SO2 coordination is reversible; a general characteristic of pyramidal M-SO2 complexes.
IrCl(C0 )(PPh3)2 + SO2 ^ IrCl(C0 )(PPh3 )2 S02 (2 )
Since SO2 accepts electron density from the metal in pyramidal complexes, the sulfur-oxygen bond order is lowered, and, as a result, the V(S0 2 ) stretching frequencies are found at lower energy than in coplanar M-SO2 complexes. Pyramidal M-SO2 complexes also irreversibly react with O 2 to form the corresponding sulfates (9).
IrCl(CO)(PPh3 >2 (8 0 2 ) + O2 ^ IrCl(S0 t)(C0 )(PPh3)2 (3) 4
A much less common type of terminal M-SOa group has only recently
been reported. Both S and 0 are attached in a bidentate fashion to the
metal in Rh(NO)(n“-SOa)(PPh3 )a (10) and RuCl(NO)(n*-S0a)(PPh3)a (11).
P P h 3
^ C 1 f : ^ R u
III
Coordination of SOa in this manner produces a slight increase in the
S-0 bond length between the sulfur and oxygen attached to the metal
compared to the terminal S-0 bond length: 1.505(5) A Vs. 1.495(5) A in
III (11). Very few trends in properties of these M-ri“-SOa complexes
have been established because of the small number of reported examples.
A unique coordination occurs in the crystalline compound
SbFs • SOa. Sulfur dioxide is bound through one of the oxygens to the
antimony (12).
— o
J'"" F I
IV
A number of complexes have been identified in which SOa bridges
two metals. Sulfur dioxide may bridge in a supported (Va) or an unsupported (Vb) mode (5): II M-S-M II 0
(a) (b)
In an interesting example of a supported SO2 bridge shown in
Equation (4), the Rh-Rh bond was formed on reaction of the dinuclear complex with SOa (13). Unsupported SOa bridges have been formed in
,CH: CHj
(Ph)aP ' P(Ph)a ( P h ) a P P(Ph)a Cl. Cl I Rh' Rh + SOa Rh Rh
(Ph)aP P(Ph); (Ph)aP P(Ph)a
CHa •CHj (4) rather unique fashions. Reaction (5) provided the first structural example of direct SOa insertion into a metal to metal bond with concurrent bond cleavage which was demonstrated by an X-ray structural study (14).
.CHa .CH:
(Ph)aP P(Ph): (Ph)aP P(Ph);
Cl-Pd- ■Pd-Cl + SO: Cl-Pd. -Pd-Cl I o ' \ (Ph)aP P(Ph)i (Ph)2P P(Ph)a
'CH: ■ CHa (5) 6
Reaction of Co(CN)s®“ , a 17-electron species, with SOa also led to
formation of a complex with an unsupported bridge (15). This reaction
appears to indicate that SOa reacts with a metal centered radical.
•Co (CN)5®“ + SOa •Co(CN)5S0a^“ (6)
•Co(CN)sSOa^“ + •Co(CN)5®“ -> (CN)sCo-S(0 )a-Co(CN)s*- (7)
One of the most extensively studied reactions of metal complexes
and SOa is the insertion of SOa into a metal to alkyl or aryl C bond
to form the S-sulfinate complexes.
[M4R + SOa -»■ [MiS(0)aR (8)
[M] = n®-CsHsFe(CO)a, Mn(CO)s, n'-CsHsCr(NO)a, etc.
R = alkyl or aryl
The scope, mechanism, kinetics^ and stereochemistry of this reaction have recently been reviewed by Wojcicki (16). The initial site of electrophilic attack is thought to be the aZphx-caxbon of the alkyl group. Reaction proceeds with inversion at the aZp/za-carbon, so that back-side attack of SOa is indicated. Initially, a tight ion pair is believed to form which rearranges to the spectroscopically observed products. The 0-sulfinate was detected in low temperature NMR and infrared spectral studies, but only the S-sulfinate is stable to isolation. Although the mechanism shown below is for ri°-C5HsFe(C0)aR> it is general for other 18-electron metal carbonyl alkyls such as n®-C5HsMo(C0)3R, Mn(CO)sR, and Re(CO),R (16). R (S + R R 6 n“-C5HsFe(C0)2-C-R + SOa n^-CsHaFeCCOa-^-SGa R R
@ 4 ^ 0 0 R n^-CsHsFeCCOa SCRa n’-CsHsFe(CD)a-^-^-R ^ \ O R
0 ,R T)*—CsHsFeCCO) a“0~S-C-R 'r (9)
Only a limited number of reactions of metal-coordinated SOa have
been reported in the literature. In numerous pyramidal M-SOa complexes
the ligated SOa reacts with Oa to form sulfates (vide supra) (5). The
reaction below may be viewed in two different ways: either insertion
of SOa into the Ir-H bond or protonation of the electron pair on the
sulfur of SOa (17).
»S-0 CO CO
Ir Ir
PPh PPh (10) Via Vib
The equilibrium was proposed since the infrared spectrum exhibited a
V(Ir-H) vibration at 1965 cm’’^ which was expected for Via, but the
NMR spectrum lacked a high-field resonance expected for the hydride attached to the iridium.
Only three reactions of metal carbonyl anions with SOa have been reported (18-21). Since SOa is a relatively weak electrophile, the 8
reactions have all involved the [r)“-CsHsFe(C0 )2 ] anion, one of the
most powerful metal carbonyl nucleophiles (22).
Unlike the insertion of SO2 into the Fe-R bond of
ri“-CsH5Fe(C0)2R (R = alkyl, aryl), reaction of ri“-C5H5Fe(C0)2CH2CSCR
with SO2 afforded a 1,3 cycloaddition product containing a sultine
ring (23).
O o fe-^CH,CsCR
VII
(T^-C gH ^Fb(CO)2 C H 2 C :C R 4- S O g
fTe-Q
(11)
VIII
In order to determine if the S-propargylsulfinate, VII, was the initial
product of reaction which then thermally isomerized to VIII,
r|®-C5H5Fe(C0)2 SO2CH2CSCR was independently prepared (23). ^H^F©(C0)2J2 * Na/Hg
C c A O ° (12) R = c C g H g VII
Since both VII and VIII were found to be thermodynamically stable species, their respective formation was attributed to kinetic factors (23),
The presumed adduct, NaEn^-CsHsFeCCO)2 SO2 ], was only formed in situ, since attempts at isolation of it unexpectedly afforded neutral products, the amounts and identity of which depend on the quantity of
SO2 employed (18-21):
Na [\v#F e^ J + SO2(excess) THF
g ° è o ' : 8 10
Na ] + S02(large excess)
^ C o
coc ° o Fe-S-Fe F e-S -S -F e C Ô i O O (14)
However , nucleophilic addition of KEri’-CsHsFe(CO)2 ] to SO2 precipitates
K[ri’-C5H 5Fe(C0 )2SO2 ]» the sole example of an isolable transition metal
sulfinate anion (24).
-78° K[ri^-CsHsFe(C0)2] + SO2 (excess) ->■ K[ri^-CsHsFe(C0)2S02] •%S02 (15) THF
The relative insolubility of thevs. Na"*" salt of [ri^-CsHsFe(CO)2 SO2 ]
was suggested to be the reason that further oxidation to form
[n=-CsH5Fe(C0)2S02]2, [n®-CsH5Fe(C0)2]2S02, or [n=-C,HsFe(C0 )2 ](C0 )(S0 2 )
was prevented (24). In either complex, M[ri®-CsHsFe(C0)2S02] (M = Na, K),
ligated SO2 undergoes electrophilic attack at sulfur with alkyl halides
to afford the S-sulfinates, n*-C5HsFe(C0)2S(0)2R (23-26).
M[n®-CsHsFe(C0)2S02] + RI ^ n^-CsHsFe(C0)2S(0)2R
+ n“-CsHsFe(C0)2l + MI (16)
M = Na, K 11
Also, Jablonskl (24) reported that reaction of K[ri“-C3HsFe(0 0 )2 8 0 2 ] with the harder alkylating agent, CH3 0 S0 2 F, proceeded with 0 -alkylation
to produce the S-methoxysulfenate, r|®-CsHsFe(C0 )2 S(0 )0 CH3 .
s K[n®-C5HsFe(C0)aS02] + CH 2OSO 2F -- > n“-C3H5Fe(C0)2-S-0-CH3 CH2CI2
+ [ri®-C5H5Fe(C0)2S02]2 (17)
The structures of [n®-C5 H5 Fe(C0 )2 ]2 S02 and [n®-CsHsFe(CO)]a(CO)(SO2 ) have been confirmed by x-ray crystallographic methods (18-20). The third isolated complex from the reaction of Na[n®-CsHsFe(C0 )2 ] and SO2 ,
[ri®-C5HsFe(C0 )2 S0 2 ]2 , was formulated as a novel type of binuclear transition metal complex in which two iron atoms are bridged by a dithionite linkage (21). Neither [n^-CsHsFe(CO) 2 1 2 8 0 2 nor
[r)®-CsH5 Fe(C0 )2 S0 2 ] 2 results from a direct insertion of SO2 into the
Fe-Fe bond in [n^-C5H 5Fe(C0 )2 ]2 at temperatures up to 25°C (26).
However, reaction between [ri®-CsH5 Fe(C0 )2 ]2 and SO2 at 40°C led to isolation of a polynuclear species which was tentatively formulated as
(n^—CsHs ) ^Fe^, (CO) i, (SO2 ) 3 (27).
Sulfur dioxide and tin(II) halides have been noted at times to exhibit similar chemistry (15,28):
M 2 (CO) 1 0 =" + SnCl2 (C0 )5M-Sn-M(C0 ) 5 = - (18) Cl (}l 0
M 2 (CO) 1 0 =" + SO2 -»■ (C0 )3M-S-M(C0 )5 =- (19) 0 M = Cr,W 12
However, only SnClz is capable of thermal insertion into the Fe-Fe bond
of [n*-C5H,Fe(C0 ) : ] 2 (29):
A [n=-C:H:Fe(C0 )2 ] 2 + SnCla ^ tn^-CsHsFeCCO)2 ]aSnClz (20) CHa OH
By far the most facile insertions of SnX2 into metal to metal bonds
have been those promoted photolytically (30,31):
U.V. [M]2 + SnCl2 [M4 Sn-[M] (2 1 ) ci &
[M] = n -C,H5Mo(C0 )a, n -C5HsW(C0 )3 , Mn(C0 )5 , Re(CO)s
These insertion reactions of tin(II) halides with metal dimers suggest
that sulfur dioxide may also react with metal dimers under photolytic
conditions to yield products where one or more molecules of sulfur
dioxide have inserted into the metal to metal bond.
The formation of [n^-CsHsFe(CO)2 8 0 2 ) 2 was most unusual, and, prior
to this study, the iron complex represented the sole example of an organometallic dithionite complex. The -S2O4 - linkage has been
structurally characterized in two different configurations. In
Na2 S2 0 i,, the oxygen atoms are eclipsed, and the S-S bond distance,
2.39 A, is much longer than S-S bonds in disulfides or polysulfides which are in the range oa. 2.0-2.15 A (32). The long bond is believed
2-
IX 13 to arise from repulsion of the lone pairs of electrons on the sulfur atoms resulting from dp hybridized bonding (33). The long S-S bond homolytically dissociates to give a pair of »SOz" radicals (3 3 ).
S2O 4 :- ^ 2S0a- (22)
The chemistry of the dithionite ion is dominated by its powerful reducing properties which result, in part, from the weak sulfur to sulfur bonding (33).
S2O4 :- + 40H“ 2 S0 3 =" + 2HaO + 2e“ (23)
E° = 1.12 V
A much different configuration of the -S2O4 - linkage is found in diphenyl-a-disulfone, C6H 5-S(0 )2-S(0 )2-C6Hs (34). In this covalent molecule the S-S bond distance is 2.193 A, and the two parallel CeHsS units of the molecule are approximately planar. The OSO angle of
120.3° is close to the value observed for sulfones (34).
-P
X
Except for studies conducted by Kice and coworkers (35-37), the
-SgO*- linkage in o-disulfones has been little investigated. The most 14 comprehensive studies conducted have involved the hydrolysis (35,36)
and nucleophilic substitution (37) reactions of diaryl-a^disulfones.
0 0 II II Ar-S-S-Ar + HgO ArSOgH + ArSOgH (24) 0 0
0 0 0 II 11-11 Ar-S-S-Ar + Nu ->■ Ar-S-Nu + ArSOg (25) II II II 0 0 0
Nu = f ", GAc ", C1“, Br", RNHj
A review of the literature shows that few transformations of SOg ligated as a Lewis base in metal complexes have been reported. In one case sulfur dioxide has been reduced (38):
trans-[(NH3 )i,Ru(S0 g)Cl]Cl trans-[Cl (NHg)^RuS]gClg (26) Zn
In a few instances reaction of SOg with a metal cation, has apparently led to subsequent nucleophilic attack by alkoxide ion at the coordinated SOg to form the alkylsulfito ligand, -S(0)g0R (39-45), e.g. 3
(PPh3)gMXg + 2CHgOH + 2S0 g (PPhg)2M(S(0 )2OCH3)g + HX (27)
M = Pd=^\ X“ = NCO"
M = Pt®"^, X" = NC0“ ,CH3C0 g"
Metal-sulfur bonding was established in
[Ni(S(O)gOC2H5)(np3)]BF^«O.5CgHsOH«0.5HgO (npg =
tris(2-diphenylphosphinoethyl)amine) by X-ray crystallography (39). 15
Ni-S 2.130G)A Co Cft S-0(1) 1 . 4 3 9 ( 7 ) A Cj» 5-0(2) 1 . 4 4 7 ( 7 ) Â
'Cm s-as) 1 . 5 9 4 ( 7 ) A XI 0 ( 3 )-043) 148(2)A
Formation of the alkylsulfito ligand, -S(0)aOR , by presumed reaction of ligated SOa and OR finds a strong analogy in the formation of alkoxycarbonyl ligands, -C(0)0R , which occurs by nucleophilic attack of OR on ligated CO (47):
0 [M^co'^ + o r " ->[M-3-C-0-R (28)
M = n°-C,H,Fe(CO)a, n®-C5H 5Ru(C0 )a, Mn(C0 )3 (PPh3 )a, Re(CO)a(PPhg^a,
Re (CO)5 , etc.
The structural similarity of metal-alkoxycarbonyl complexes,
[M#C(0)0R (M = metal carbonyl), and organic carboxylic esters,
R ’C(0)0R" , was recognized and explored. Many typical transformations of esters such as hydrolysis, transestérification, and conversion to amides (48,49) have been found to proceed for alkoxycarbonyl complexes.
Hydrolysis of ri°~C5HsFe(C0 )2C(0 )0 CH3 and Mn(C0 )5C(0 )0 CH3 was proposed to afford the carboxylic acid intermediates,
Ti®C5H 5Fe(C0 )2C(0 )0 H and Mn(C0)sC(0)0H, respectively, which readily decarboxylated to the corresponding hydrides ri“~CsH5 Fe(C0 )2H and
Mn(CO)sH (50). 16 [M^C(0)0CH3 + HaO [NiC(0)0H + CHgOH
M = n®-CsHsFe(C0 )2 , Mr, (CO) 5 ^ [M4H + COa (29)
However, if one CO was substituted with PPha in the iron complex, the carboxylic acid was stable to isolation, which substantiated the
OH" = 0 ,Fe
° P P h 3 O 'H (30) intermediacy of the metallocarboxylic acids in reaction (29) (51). Other noteworthy transformations of the alkoxycarbonyl ligand are the reactions with amines to form the carbamoyl complexes (52) and transestér ifications (53).
Re(C0 )sC(0 )0 CH3 + CH3NH2 Re(C0 )sC(0 )NHCH3 + CH3OH (31)
PtCl(C(0 )0 CaH5 )(PPh3 ) 2 + CH3OH ->■ PtCl (C (0 )0 CH3 ) (PPha ) a-fCaHsOH (32)
The alkylsulfito ligand in metal complexes, MS(0)aOR, is structu rally similar to organic sulfonic acid esters, R'S(0)aOR" . Although hydrolysis of both carboxylic acid esters and sulfonic acid esters leads to formation of the corresponding acid, sulfonic acid esters have an alkylating action and, thus, differ considerably from carboxylic acid esters in many other chemical reactions (54). At the start of 17 this study transformations of the alkylsulfito ligand had not been investigated.
Complexes containing the alkoxycarbonyl ligand react with acids to generate the metal carbonyl cations (47), e.g.i
n®"CsHsFe(C0)2C(0)0CH3 + HCl [n'-CsHsFeCCOjajCl + CH3OH (33)
Pettit (51) reported that ^*-CgH3Fe(C0 )(PPh3 )C(0 )0 R (R = H,CH3 ) spontaneously ionized in polar solvents with heterolytic cleavage of the carbon to oxygen bond.
HC( 0 )NH 2 i -
For R = CH3 in chloroform the IR spectrum exhibits a single terminal metal carbonyl absorption at 1935 cm“^ and a ketonic absorption at
1605 cm“ \ but in formamide there are two terminal carbonyl absorptions at 2030 and 2080 cm~^, indicative of ionization. The spontaneous heterolytic cleavage of the C-0 bond has no precedence in organic carboxylic acids. Neutral [M#S(0 )2 0 R complexes may represent possible precursors of cationic metal-S0 2 species, formed by the same methods as shown above for the generation of metal carbonyl cations from the alkoxycarbonyl complexes. 18
The major goal of this thesis was to expand the realm of synthesis
and chemistry of organometallic complexes which contain sulfur-oxygen
ligands. This work will report the interaction of metal carbonyl anions, radicals, and cations with sulfur dioxide and subsequent transformations of the metal-bound sulfur dioxide. Complexes which resulted from these interactions contain dithionite and alkylsulfito ligands. The reactivity of the dithionite linkage was explored; reactions of the alkylsulfito ligand led to the formation of many new sulfur-oxygen ligands. EXPERIMENTAL
I. Reagents and Solvents
A. Organometallic Reagents
Strem Chemicals supplied [ri®-CsHsFe(C0 ) 2 Ja and [n'-CsHsMo (CO)3 ] z which were recrystallized from benzene before use. Strem Chemicals
also provided Mn2 (C0 )io, Re2 (C0 )io, Co2 (C0 )e, and WfCO)* which were
purified by sublimation at 70°C/0.1 torr, 70°C/0.1 torr, 25°C/0.1 torr,
and 80°C/1 torr, respectively, before use. Mr. F. Regina furnished
O^-CsHsCr(N0 )2C1 , Dr. 0. Hackelberg furnished Mn(CO)sBr, and Ms. G.
Arzaga kindly donated ri°-CsH5 FeCC0 )2 l and n^-CsHsFeCCO) (PPh3 )I.
B. Other Reagents
Sulfur dioxide was obtained from the Matheson Co., and was purified before use by passage through concentrated H 2 SO4 and a
column packed with P*Oio«
Fisher Scientific supplied CH3 I, C2H 5 I, (CH3 )2 CHI, CzHsBr, and
(CH3 )2CHBr which were used as received. Aldrich was the source of
CH3 SO3F, (CH3)3 0 PFe, and (C2Hs)3 0 PF6, but only (C2Hs>3 0 PF6 was purified by recrystallization from methylene chloride before use.
1-Propanol and 2-propanol were provided by Baker and were distilled from CaSOt onto 4A molecular sieves (Union Carbide) before use (55).
Ethanol was purchased from the U. S. Industrial Chemical Co. and used
19 20
as received. Methanol, obtained from Mallinckrodt, was distilled
from magnesium turnings and I2 onto 4 A molecular sieves (56). O ( + ) 5 8 9-2 ~0 ctanol ([a]s§9 ® + 8.75°) was supplied by Aldrich and
distilled at 86°C/20 torr before use.
Dimethylamine, diethylamine, and triethylamine were obtained O from Fisher Scientific and stored over 4 A molecular sieves (Union
Carbide). Triphenylphosphine from Chemical Samples was recrystallized
from benzene before use, but tri-n-butyl phosphine from Aldrich was
used as received.
Dimethylsulfamoyl chloride, purified by distillation at 114°C/75
torr before use, and triglyme, purified by distillation from CaHj and
passage through a column of activated alumina, were purchased from
Eastman Chemical Co., Aldrich supplied 2,2'-bipyridine, dicyclopent-
adiene, and oxalyl chloride, and Fisher supplied thionyl chloride.
Deuterium oxide was purchased from Columbia Organic Chemicals.
Fluoroboric acid, 48% aqueous solution, was obtained from the J. T.
Baker Chemical Co.
Merck was the source of sodium sulfite, whereas mercury(II) bromide
and p-toluenesulfonic acid were obtained from Matheson, Coleman, and
Bell. Sodium sulfide from Mallinckrodt was dehydrated by heating at
60°C/1 torr for 48 hours and 120°C/1 torr for 25 hours (57). Sodium
tetraphenylborate was purchased from Aldrich and recrystallized from
CHCI3. Silver tetrafloroborate from Alpha Inorganics was dehydrated by heating at 120°C/1 torr for 24 hours and then at 145°C/1 torr for
1.5 hour. 21
Hydrogen chloride gas was obtained from Precision Gas Products, and hydrogen fluoride gas was supplied by Matheson. Both gases were used as received.
C. Chromatographic Materials
Activated magnesium silicate ("Florisil" , 60-100 mesh) was supplied by J. T. Baker and used as received. Activated neutral alumina was purchased from Alpha Inorganics (Ventron) and was deactivated by addition of 6 % by weight of water.
D. NMR Solvents and Standards
Merck, Sharpe, and Dohme, Canada, Ltd. supplied perdeuteromethy- lene chloride, perdeuteroacetone, and perdeuterodimethyl sulfoxide.
Deuterochloroform, perdeuteroacetonitrile, and tetramethylsilane were pruchased from the Aldrich Chemical Company. Deuterium oxide was obtained from Columbia Organic Chemicals.
E. Solvents
All solvents were reagent grade, and most were purified and/or dried by methods described by Perrin, et at, (55). Tetrahydrofuran
(THF) was distilled from Na/K and benzophenone immediately before use.
After chloroform was initially distilled from P\Oio, it was distilled from K 2CO3 onto 4 Â molecular sieves. Dichloromethane was distilled from P 4O 10 and stored over 4 A molecular sieves. Acetonitrile was distilled three times from P^Oao, once from K2CO3, and then stored O over 4 A molecular sieves. Nitromethane was predried by storage over
CaCl2 and distilled from CaSOt onto 4 Â molecular sieves. Cyclohexane 22
was distilled from LlAlHz,. Both diglyme and dimethoxyethane, which
were very wet, were twice distilled from CaHg, and stored over 4 Â
sieves. Benzene and toluene were dried by passage through a column
of alumina (58). Diethyl ether, acetone, and ethyl acetate were used
as received.
II. Instrumental and Physical Methods
Infrared spectra were obtained on either a Perkin-Elmer Model 337
spectrophotometer or a Beckman IR-9 spectrophotometer. The spectra
were calibrated with polystyrene. Solid state spectra were obtained
as Nujol or Fluorolube mulls and KBr pellets. Matched 0.1011 mm
NaCl or 2.011 mm KBr solution cells were used for solution measurements.
Proton NMR spectra were initially recorded on a Varian Associates
A60-A spectrometer and, later, on a Varian Associates EM-360 spectro meter with TMS employed as an internal reference.
Ultraviolet-visible spectra were recorded on a Cary 15 spectro
photometer with matched 0 . 1 cm or 1 cm quartz solution cells.
Mass spectra were obtained by Mr. C. R. Veisenberger with an
AEI MS-9 mass spectrometer.
Osmometric molecular weight determinations were performed on the
Mechrolab Vapor Pressure 301-A osmometer.
Conductivity data were obtained in aa. 10“^ M solutions in a
Lab-Line Unbreakable Beaker-type Conductivity Cell, Cat, No. 11200. The cell constant was approximately 0.1. An Industrial Instruments, Inc., 23
conductivity bridge. Model RC16B2, was used to determine the cell
resistance at 1000 Hz.
Specific rotations were measured on a Perkin-Elmer polarimeter,
Model 241, in solution cells with a volume of 1 mL and length of 10 cm.
Titrations were performed using a Radiometer Copenhagen Auto burette, Model ABU12, a Radiometer Copenhagen Titrator, Model No. 11, and a Radiometer Copenhagen pH Meter, Model No. 26.
Melting points were determined for samples sealed under vacuum in glass capillaries in a Thomas-Hoover capillary melting point apparatus and are uncorrected.
Elemental analyses were performed by Galbraith Laboratories,
Knoxville, Tennessee.
III. General Experimental Procedures
Standard techniques for the manipulation of air-sensitive compounds were employed for syntheses (59). Frequently, a Kewaunee
Scientific Equipment dry box purged with argon was utilized for handling compounds or conducting reactions which were sensitive to air or moisture. Some filtrations, especially at low temperatures, were performed using a polyethylene filter-tube and inert gas pressure, a technique described elsewhere (60).
A Rayonet RPR-100 Photochemical Chamber Reactor was used for photochemical reactions. Sixteen interchangeable lamps (Cat. No. R.P.R.
3500 Â) of 3500 Â irradiation were used within the reactor. The O maxima for the lamps is found at 3500 A, but the spectral distribution 24
ranges from 3050 A to 4250 A. The apparatuses depicted on pages 29
33, and 39 were used for the photolysis studies.
IV. Literature Preparations
Reaction of W(C0)6 and dicylopentadiene in refluxing triglyme
afforded [n^-C5HsW(C0 )3]2 (61).
Reduction of the dimeric complexes, [M]g (M = p^-CsHsFeCCO):,
ri^-C5HsW(C0 )3 , and n^“CsHsMo (C0)3 ), with excess 1 % sodium amalgam in
THF, afforded the corresponding sodium carbonylate salts (62), Na[M], which were used in situ.
Compounds of the type [M]aHg (M = ri^-CsHsFe(CO) 2 (63), n^-C5HsMo(C0 ) 3 (64), n®-CsH5W(C0 ) 3 (64), and Co(CO)* (65a), were prepared by addition of HgBr2 to a THF solution of Na[M] , and
[(n-Bu3 P)Co(C0 )3 ]2Hg was prepared by addition of n-Bu3? to a benzene solution of [Co(CO)z,] zHg (65b).
Passage of oxygen through a solution of [n^-CsHsFe^CCOzJz and HCl in CHCls-ethanol afforded ri^“CsH5Fe(C0 ) 2CI (6 6 ). Passage of oxygen through a solution of [n^-CsHsFe(C0 )2]2 and 48% fluoroboric acid in acetone afforded [ri®-C5H 5Fe(C0 )2H 2 0 jBFi, (67). Reaction of AgBF^ and n®-CsHsFe(C0 )2 l in THF produced tn^-CsHjFe(CO)2 (THF)]BF^ (6 8 ).
When a solution of [r|®-CsH5Mo(CG)3 ]z was refluxed in toluene,
[ri’-C5H 5Mo(C0 )2 ]z was formed and used in situ (69).
Reaction of K[n^-CsH5Fe(C0 )2 ], formed by reduction of
[ri®-C5HsFe(C0 )2 ] with excess Na/K2 .e in THF, with SO2 at -78°C afforded K[n^-C5H5Fe(CG)2 SO2 ]•%S0 2 (24). 25
Passage of Cl2 through a solution of Mn2 (C0 )io in CHCI3 produced
ClMn(CO)s (70,71). When ClMn(CO)s was treated with 2,2'-bipyridine in
CHCla or two equivalents of PPha in CHCI3 , ClMn(CO)3 (2,2'-bipyridine)
(72) and ClMn(C0 )3 (PPh3)2 (70,71) were prepared, respectively.
The sodium alkylsulfites, Na[S(0 )2 0 R] (R = CH3, C2H5), were prepared by slow introduction of gaseous SO2 to a cooled (0°C) alcoholic solution of NaOR (R = CH3, C3H5), produced by reaction of Na and ROH
(73,74).
Oxidation of (CHa)3N with H 2O 2 afforded (CHa)3N0 (75).
Metathesis of TI2CO3 and NaaSaOz, in an air-free aqueous solution precipitated TlaSaO^, which was collected by filtration (76).
V. The Preparation, Characterization, and Reactions of Some New Sulfur-Oxide Ligands in Organo-Transition Metal Complexes
A. Organometallic Dithionite Complexes
Preparation of [n^-C5H5Fe(C0 )2 S0 2 ] 2
1. By Reaction of Na[ri®-CsH5Fe(C0 )2 ] with SO2
A solution of Na[ri“-CsH5Fe(C0 )2 ], obtained by reduction of 3.54g
(10.0 mmol) of [r)®-CsHsFe(CO)2 ]3 with excess 1 % sodium amalgam in 150 mL of THF, was cooled to -78°C. Treatment of the solution with 10 mL of liquid SO2 in 10 mL of THF immediately produced an orange solution.
After the -78°C bath was removed, the solution warmed to 25°C over a period of one hour. The solution was filtered to remove suspended insolubles, and the solvent was removed by rotary evaporation.^
^ Based on the infrared and *NMR spectra of this crude material, both lTi“-CsH5Fe(C0 )2 S0 2 j2 and [r)®-C5H5Fe(C0 )2 ]2 S0 2 are present. 26
The residue was dissolved in the minimum amount of CHCla, and this
solution was added to a 2,5 x 27 cm Florisil column. Initial elution
with CHCI3 produced a purple band which was collected. Rotary
evaporation of the solvent from this fraction recovered 0.350g (1.00
mmol) of unreacted [ri*-CsH5Fe(C0 )2 ]a •
Elution with 1:5 (v/v) acetonetCHCla moved an orange band which
was collected and evaporated to dryness. Extraction of the residue
with CHCla, followed by slow addition of cyclohexane, produced 0.773g
(16.0%) of an orange powder identified as [ri®-CsH5Fe(C0 )2 S0 2 j2 .
Melting Point 140-146°C
Analytical Data Calc, for CitHioFeOeSg: 34.88% C, 2.09% H, 13.30% S Found: 35.08% C, 2.10% H, and 13.20 % S
Molecular Weight (CHCla) Calc, for CitHioFeOgSg; 482g/mole Found : 501 g/mole
NMR (CDCls)T 4.64, singlet, C5H 5
IR(CHCl3 ) 2070(s), 2059(s), 2044(s) cm"^ IR(Nujol) 3140(w), 1223(s), 1068(w), 1040(s), 1018(w), 890(w), 862(sh), 850(m), 835(m), 609(s), 570(s), 558(sh), 550(s), 515(m), 498(m), 492(m), 445(m) cm~^
U.V.-Vis. (CHCI3) 318nm(sh), 438nm (e = 7,100)
Mass Spectrum (70eV, 80°C) ™/e = 354 for [n^-CsH5Fe(C0 )2 ]2 ^ ™/e = 64 for SOa"*" See Table in Appendix
Elution with acetone produced a third, bright red band which was
collected. After rotary evaporation of the solvent, the red material was identified by infrared spectroscopy as [r)“-CsHsFe(C0 )2j2 S0 2 , 0.150g
(3.59%). Finally, elution with MeOH moved a very narrow red band down the column. Rotary evaporation of the solvent afforded a trace amount 27
of [n*-CsH5Fe(CO)2 ](CO)SOa, which was identified by infrared spectro
scopy.
2. By Reaction of [n-CsHsFe(C0 )2 ]aHg with SO2
A flask containing 1.61g (2.91 mmol) of Iri*“C5HsFe(C0 )a]2Hg and
attached to a dry ice condenser was cooled to -78°C. After 20 mL of
liquid SO2 was condensed into the flask, the -78"C bath was removed
from the flask, and the SO2 was allowed to reflux at -10°C for nine
hours. As the solution was warmed to 25°C, the SO2 evaporated and an
oily residue resulted. The oily residue was dissolved in CH2 CI2 , and
filtration of this solution through a sintered glass filter funnel
removed 0.13g (0.63 mmol) of metallic Hg.
The filtrate was introduced to a 3.8 x 22 cm Florisil column, and
elution with CH2CI2 produced a purple band. Removal of solvent afforded
0.065g (6.3%) of [ri^“C5H 5Fe(C0 )2 ]2 . Continued elution with CH2CI2 moved a yellow band which contained 0.048g (3.0%) of unreacted
[n®-CsH5Fe(C0)2]2Hg.
When the solvent was switched to 1:2 (v/v) CH2CI2 :acetone, a long orange band was collected. After removal of the eluting solvent, recrystallization of the orange material from CH2CI2 by addition of cyclohexane yielded 0.390g (23%) of [ri*-C5HsFe(C0 )2 SO2 ]2 .
Elution with MeOH moved a band which originally was orange-red but lightened to yellow while passing through the column. Evaporation of the solvent produced 0.524g of an unidentified yellow material.
Elemental Analysis Found; 29.21% C, 2.09% H, 10.29% S Ratio C/H/S = 7.6 /6 .5/1 28
IR(Nujol) 2031(s), 1969(s), 1085(s), 1015(m), 976(s), 844(m), 836(m), 634(sh), 615(s), 579(s), 562(s) cm“ ‘
Mass Spectrum(70eV, 80°C) Material decomposed in mass spectro meter,^but a weak isotopic pattern for Hg was observed, as well as a peak at ™/e = 186 for (ri°-C5H 5 )aFe .
3. By Photolysis of [r)®-C5H 5Fe(C0 )2 ]a and SO;
A solution of 0,333g (0.941 mmol) of [n'-C5HsFe(C0 )2]2 in 50 mL of
THF in the apparatus shown in Figure 1 was saturated with gaseous SO2 at 25°C. The solution was photolyzed with 3500 A lamps for 10 minutes under CO purge. After SO2 was passed through the solution for 10 minutes, the solution was again photolyzed. This cycle was repeated three times for a total photolysis time of 40 to 45 minutes. During this time the solution darkened, and an orange-brown precipitate formed.
The contents of the apparatus were transferred to a flask, and the THF was removed from the flask by rotary evaporation.
The residue was partially dissolved in CHCla, and the resulting solution was chromatographed on a 2.2 x 20 cm Florisil column. Initial elution with CHCI3 produced a purple band which yielded 0.125g of unreacted [ri*“C5H 5Fe(C0 )2 ]2 after removal of solvent. Elution with acetone: CHCI3 (v/v) 1:3 moved an orange band which contained 0.102g
(22.5%) of [n“-CsHsFe(C0 )2 S0 2 ]2 . Finally, when CHaOH'.acetone (v/v)
1:10 was used as the eluting solvent, a band which contained 0.009g of
[ri““CsHsFe(C0) J2 (CO) (SO2 ) was collected. Large amounts of brown decomposition materials (no carbonyl bands in the infrared spectrum) remained at the top of the column. 29
S O 2 .C O .N 2
To bubbler
[m] p solution
•Gas dispersion S tube
Figure 1. Apparatus for Photolysis of [M]z and SO2 at 20®C. 30
4. By Reaction of [ri®-C5H 5Fe(C0 )2 ]aS0 2 with SO2
A solution of 0.033g of [n°-CsHsFe(C0 )2 ]S0 2 in 10 mL of THF was cooled to -78°C, Approximately 5 mL of liquid SO2 was condensed into the solution, and the resulting solution was stirred at -78°C for 2 hours and then warmed to 25°C over a period of one hour. After the solvent was removed by rotary evaporation, the residue was dissolved in 5 mL of acetone. Application of the extract to a 1.9 x 10 cm
Florisil column and elution with acetone;CHCla (v/v) 1:1 passed an orange band down the column. After the orange fraction was collected and the solvent was removed by rotary evaporation, 0.007g (30%) of
[0 ^-C5H 5Fe(C0 )2 S0 2 ] 2 was isolated. Elution with neat acetone moved a red band which contained 0.025g (6 6 %) of unreacted [ri®-C5H 5Fe(C0 )2 ]S0 2 .
Preparation of [Mn(CO)5 SO2 ]2
In a typical reaction 1.55g (4.08 mmol) of Mn 2 (C0 )io was charged to the apparatus in Figure 2. Under CO atmosphere 20 mL of liquid SO2 was condensed onto the Mn2 (C0 )io. The solution was photolyzed for 6 hours with 3500 Â lamps. During this time the solution had slowly darkened from a pale yellow to a deep red color.
After the SO2 had evaporated, the residue was extracted with five
40 mL aliquots of cyclohexane. The yellow cyclohexane extracts were combined, and, after removal of the solvent, sublimation of the residue recovered 0.17g (11%) of unreacted Mn2 (C0 )io. Since the major portion of the residue was insoluble in cyclohexane, it was extracted with
150 mL of benzene. Filtration of the extract gave a yellow solid and a red filtrate. 31
After evaporation.of the solvent from the filtrate 0.201g of purple-red crystals of an unidentified product was isolated.(IR spectrum did not contain SO2 bands, so the material was not further characterized).
Infrared Spectrum (Nujol) 2160(w), 2115(sh), 2040(s), 1985(sh), 1930(s), 1160(w), 1075(w), and 975(w)
The yellow solid was treated with 15 mL of THFrCHaOH (v/v) 1:1, and most of it dissolved. Filtration of the solution resulted in the collection of 0.191g of [Mn(C0 )5 S0 a]2 . Addition of 15 mL of cyclohexane to the filtrate and cooling to 0°C precipitated 0.041g of additional
[Mn(CO)5 SO2 ]2 which was collected by filtration. Total yield: 0.232g
(11%).
Melting Point (vacuum) 115-124°C (dec.)
Analytical Data Calc, for CioMngOitSz: 23.18% C, 0.00% H, 12.38% S Found: 23.12% C, none or trace % H, 12.28% S
Molecular Weight (CH3CN) Calc, for CioMnzOitSz: 518.1g/mole Found; 47Og/mole
IR (CH2CI2) 2146(m), 2090(sh), 2060(s), 2040(s)
IR (Nujol) 2138(s), 2096(s), 2071(s), 2050(s), 2032(s), 1998(sh), 1224(s), 1195(w), 1070(w), 1037(s), 630(vs), 538(w), 522(w), 512(m), 498(w), 458(s) cm"'
U.V.-Vis. (CHCla) 383 nm (e=1670)
Mass Spectrum (80°C) “ /e = 390 for Mna (0 0 )10"^ ”*/e = 64 for SOa^ See Table in the Appendix 32
Preparation of [Re(0 0 )5 8 0 2 32
In a typical reaction 1.30g (2.35 mmol) of Rea(CO)ao was dissolved
in 40 mL of benzene in the apparatus shown in Figure 2. Under CO
atmosphere 30 mL of liquid SO2 was condensed onto the benzene solution.
The solution was then photolyzed for 8.5 hours with 3500 Â lamps, during
which time it slowly changed from a light yellow to a bright orange
color.
Evaporation of the SOa resulted in the formation of a white
precipitate in the benzene solution. An additional 80 mL of benzene was added to the solution, and filtration separated a white precipitate
from an orange filtrate. Removal of solvent from the filtrate by rotary evaporation gave an orange solid. Sublimation of this material recovered 1.15g (88.3%) of unreacted Rea(CO)1 0 .
The white precipitate from above was treated with 25 mL of THFiCHgOH
(v/v) 4:1, and some of the material dissolved. Filtration of the solution gave a clear filtrate and a white solid which was identified as [Re(CO)sSOa]a, 0.055g (3.5%).
Melting Point (vacuum) 168-170°C (dec.)
Analytical Data Calc, for CioOiJReaSa: 15.39% C, 0.00% H, 8.21% S Found: 15.53% C, none or trace % H, 8.49% S
IR (CHaCla) 2150(m), 2090(sh), 2060(s), 2035(s) cm” ^
IR (Nujol) 2154(s), 2097 (s), 2076(s), 2059 (s), 2038(s), 2020(s), 1986(sh), 1970(sh), 1212(s), 1190(w), 1069(w), 1031 (s), 590(s), 580(s), 574(m), 560(m), 423(s) cm-i 33 To bubbler
Dry ice-acetone cDry ice bath condenser
S O g .C O , N2
[m]- solution'^
rring bar
Figure 2. Apparatus for Photolysis of [M]a and SO2 at -10°C. 34
Mass Spectrum (80°C) ^/e = 552 for Reg(CO)i© ™/e = 64 for SOg^ See Table in the Appendix
Attempted Reaction of NaEn^-CsHsMo(CO)3 ] and SO2
A solution of Na[n°-C5HsMo(CO)3 ], obtained by reduction of 2.42g
(5.03 mmole) of [n’-C5HsMo(C0 )3]2 with excess 1% sodium amalgam in
200 mL of THF, was cooled to -78°C. Upon addition of 5 mL of liquid
SO2 the solution immediately changed from pale yellow to dark red in color. After the solution was stirred at -78°C for one hour, it was allowed to warm to room temperature. The solution was then filtered through a funnel packed with 2 cm of Florisil and the solvent was removed by rotary evaporation. The purple residue was extracted with acetone and the resulting mixture was eluted with CH2CI2 :hexane (v/v)
1:1 on a 5 x 13.5 cm column packed with grade III alumina. Elution initially moved a yellow-orange band which gave a yellow-green material after collection and removal of solvent. The material was identified as 0.578g (17.0%) of tU^-C5H 5Mo(C0 )3 ]2 Hg by *H NMR and IR spectro scopy (77).
IR (Nujol) 1990(G), 1955(s), 1895(s), 1865(s), 1845(g ), 1016(w), 845(sh), 824(w), 822(w), 590(m), 567(a), 500(m) cm""
NMR (CDCl3 )T 4.58, C 5H 5
Acetone was employed as the solvent to move a red-purple band. After collection and removal of the solvent by rotary evaporation, 0.989g
(40.7%) of the lu^-CsHsMo(0 0 )3 ] 2 was recovered. 35
Attempted Reaction of [ri^-CsHsMoÇCOjaJaHg and SO2
Approximately 10 mL of liquid SO2 was condensed onto a solution
of 0.822g (1.21 mmole) of [n^-CsHsMoCCOaJaHg in 60 mL of THF. As the
solution refluxed for 24 hours at -10°C, it darkened from a yellow to
green color. Upon evaporation of the solution to dryness a yellow
solid was obtained. The solid was extracted with 40 mL of CHCI3 , the
resulting solution was filtered to remove any insolubles, and cyclo
hexane was added to the filtrate to precipitate 0.787g (95.7%) of
unreacted [ri^-CsHsMo(0 0 )3 ]aHg.
Photolysis of [ri^-CsHsMo(CO)3 ]a and SOa
In the apparatus shown in Figure 2, l.OOg (2.00 mmol) of
[n*-C5HsMo(C0 )3 ]a was dissolved in 30 mL of THF. After 5 mL of liquid
SOa was condensed onto the solution under CO atmosphere, the resulting solution was photolyzed with 3500 A lamps at -10°C. During the course of reaction the solution darkened, and a brown precipitate formed.
The SOa was allowed to evaporate, the mixture was transferred to a flask, and the THF was removed by rotary evaporation. The resultant residue was extracted with CHCI3, and the extract was added to a 2 x
20 cm column of Florisil. Elution with CHCI3 moved a purple band which contained 0.598g of unreacted [ri^-CsHsMo(CO)3 ] a • When the solvent was switched to acetone, an orange band passed down the column. After collection of the band and removal of the solvent by rotary evaporation,
0.077 (12%) of a material identified as (rj^-CsHs)aMoaSaOa (78) was isolated. 36
Melting Point >250°C
IR(KBr) 3085(m), 1530 (sh), 1510(s), 1450(w), 1060(w), lOlSCs), lOOO(s), 928(vs), 837(s), 805(vs), 738(w), 680(m) cm"^
Mass Spectrum See Table in the Appendix
Reaction of [ti^-CbHsMo(CO)2)2 and SO2
A solution of 0.37g (0.80 mmol) of [n’-CsH5Mo(C0 )3 ] 2 in 50 mL of
toluene was refluxed for 24 hours. After 24 hours the decarbonylation
of [n^-CsHsMo(0 0 )3 ) 2 to [r|®-C5HsMo(C0 )2 ]2 had leveled off with incomplete
conversion. In the infrared spectrum of the toluene solution the CO
peaks at 1889 and 1859 cm~* for [n'-CsHsMo(CO)2]2 were about 4 times
as intense as the CO peaks at 1960 and 1915 cm“^ for [n^-CsHgMo(0 0 )3 J2
(69).
The solution was cooled to 0 °C, 1 mL of toluene saturated with SO2
(0.22g of S0 2 /mL of toluene) (79) was added, and the solution was
stirred at 0 °C. After 45 minutes there was no apparent color change,
and the toluene was removed by rotary evaporation to yield a red solid.
The solid was treated with 10 mL of CHCI3, and the mixture was added
to a 2.7 X 29 cm Florisil column packed in CHCI3. Elution with CHCI3 moved a red-purple band which yielded 0.181g of unreacted
[n'-C5HsMo(C0 )3 ] 2 when the solvent was removed by rotary evaporation.
When the eluting solvent was changed to acetone, an orange-red band was collected. The material was identified as (ri*-C5Hs)2Mo2S2 02
(0.073g, 23%) by infrared spectroscopy. 37
Attempted Reaction of Na[n°-CsH3W(C0 )3 ] and SO2
A solution of Na[ri“-CsH5W(C0 )2 ] was prepared by reduction of
l.OOOg (1.5 mmol) of [ri^-CsHgWCCO) 2 ] 2 with excess 1% sodium amalgam
in 100 mL of THF. The solution was cooled to -78°C, and condensation of 10 mL of liquid SO2 onto the solution produced an immediate color
change from yellow to purple. After stirring for 25 minutes at -78°C
the solution was allowed to warm to room temperature over a period of one hour. The solvent was removed by rotary evaporation, and the resultant residue was extracted with 20 mL of CH2CI2 . The slurry was added to a 2.4 x 30 cm Florisil column, and elution with CH2CI2 produced a red-purple band. Evaporation of this fraction afforded
0.701g of unreacted [r)°-CsHsW(C0 )3 ]2 . When the solvent was switched to CH2CI2 :acetone (v/v) 1 :1 , an orange band passed down the column.
After collection of the band and removal of solvent, the orange material was identified as (ri^-C5Hs)2W 2 S2 0 2 , 0.054g (6.1%).
Melting Point >250°C
Analytical Data Calc, for Ci0H 1 0 O 2 S2W 2 : 20.09% C, 1.70% H, 61.90% W Found; 20.22% C, 1.43% H, 61.99% W
IR(KBr pellet) 3075(m), 2082(vw), 1500(m), 1065(m), 1015(s), 998(s), 910(s), 851(s), 836(sh), 817(vs), 675(m) cm""
Mass Spectrum See Table in the Appendix
When CHaOH was used for elution, a yellow band passed down the column. Evaporation of the solvent from the collected fraction yielded
0.176g of a yellow, unidentified material, compound " A " , During attempts at recrystallization of this material from acetone by slow addition of ether, it decomposed to a white solid. (The infrared 38
spectrum of the white solid contained no bands attributable to S-0
stretching absorptions.)
Melting Point 142-145°C (dec.)
Analytical Data 1) 19.30% C, 2.03% H, 7.49% S, 50.21% W Ratio C/H/S/W = 6.8/8.6/1/1.17
2) 20.80% C, 1.90% H, 7.17% S, 37.88% W Ratio C/H/S/W = 8.4/9.2/1.09/1
IR(Nujol) 2038(s), 1945 (s), 1895(s), 1141 (s), 1078(m), 1063(s), 1016(w), 974 (s), 845(m), 835(m), 634(s), 565(m), 525(m) cm"*
Mass Spectrum See Table in the Appendix
Attempted Reaction of [n^-CsH5W(C0 )g]2Hg and SOg
Excess liquid SO2 , 5 mL,was condensed onto a solution of 0.60g
(0.72 mmol) of [ri*-C5H 5W(C0 )3 ]2Hg in 50 mL of THF at -78°C. The SO2 was refluxed at -10°C for 14 hours and then was allowed to evaporate.
During the course of reaction there was no detectable color change or precipitation of elemental Hg. After the THF had been removed, an infrared spectrum of the residue identified it as unreacted
[n“-CsHsW(C0)3]2Hg.
Photolysis of [n°-C5H 5W(C0 )3 ]2 and SO2
In the apparatus shown in Figure 3, 0.203g (3.05 mmol) of
[ti*~CsHsW(CG)3 ] 2 was dissolved in 50 mL of THF under CO atmosphere.
After approximately 5 mL of liquid SO2 was condensed onto the solution the system was sealed off. The solution was then photolyzed for 2 e hours at -10°C with 3500 A lamps, during which time it changed from a 39
T o b u b b l e r Evacuated 500 m .g a s b u lb
Dry ice-acetone b a t h \ r v
Dry ice condenser
CO,SO
T H F Solution of (n^-C5H5)W(CO)3]
Stirring bar o
Figure 3. Apparatus for the Collection of Gases from
Photolysis of [n=-CsHsW(C0 )3 ]2 and SO2 . 40
red-purple to orange in color, and a brown precipitate formed. The
evacuated gas bulb was opened to the reaction system, and a gas sample was collected. The apparatus was opened, and the SO2 was allowed to evaporate. The solvent was removed from the THF solution to produce a brown residue.
Some of the gas in the bulb was transferred to a gas infrared cell, and the rest of the gas sample was used to obtain a mass spectrum.
The infrared and mass spectra both confirmed the presence of CO2 (80).
IR (Gas) 2350 cm"" (80)
Mass Spectrum (Ambient ™/e = 44 for CO2T (weak) temperature) ™/e = 80 for SOs^ (very intense)^ /e = 64 for SO2 (very intense) ^/e = 48 for SO"*" (very intense)“
The reaction residue was extracted with 15 mL of CH2CI2 , and the extract was added to a 2.5 x 16 cm Florisil column. Elution with
CH2 CI2 moved a red band which yielded 0.038g (19%) of unreacted
[n^-C5H 5W(C0 )3]2 after collection and evaporation of the solvent.
Elution with CH2CI2 :acetone (v/v) 2:1 produced 0.051g of a green material which was discarded (IR spectrum did not contain bands for
SO2 , so the material was not further characterized). When the solvent was switched to acetone, an orange band was collected. After removal of the solvent by rotary evaporation, the orange powder was identified as 0.034 (19%) of (n=-C,H5 )2W 2 S2 0 2 .
Finally, elution with MeOH produced a yellow band which passed through the column. This fraction was collected and concentrated to
Peaks at /e = 80 for SOg^ and °*/e = 48 for SO may result from ionization of SO2 , since a gas sample containing only SO2 gave the same results. 41
10 mL. Dropwise addition of ether induced precipitation of a canary
yellow material. Infrared and mass spectroscopy showed that this
was compound " A " (vide supra), 0.03g.
Attempted Reaction of [Co(C0 )4 ]aHg and SO2
Excess liquid sulfur dioxide, 20 mL, was condensed onto a solution
of 1.13g (2.10 mmol) of [Co(C0 )4 ]aHg in 50 mL of THF. After 15 hours
under SO2 reflux the solution had darkened, and the volatiles were
then removed by evaporation. The residue was extracted with CH2CI2 ,
and the extract was charged to a 2.8 x 28 cm Florisil column. Elution with CH2CI2 moved a yellow band which yielded 0.968g (85.7%) of
unreacted [Co(C0 )4 ]2Hg after rotary evaporation of the solvent. When
the solvent was changed to acetone, 0.05g of an unidentified orange
solid was collected. (The IR spectrum did not contain SO2 bands, so
the material was not further characterized.)
IR(KBr) 2050(sh), 2030(s), 1970(s) cm“"
Attempted Reaction of [(n-Bu3P)Co(CO)3 ]2Hg and SO2
On the vacuum line 25 mL of liquid SO2 was condensed onto 0.94
(1.1 mmol) of [(n-Bu3P)Co(C0 )3 ]2Hg in 15 mL of THF in a 3 x 15 cm Pyrex cylinder which could be sealed off by closure of a Teflon stopcock.
After stirring for 3 days at 25°C the solution changed color from yellow to brown, but no metallic Hg was formed. The SO2 and THF were removed by evaporation, and the resultant residue was taken-up in
CH2CI2 . This extract was charged to a 2.5 x 10 cm grade III alumina column, and elution with CH2CI2 recovered 0.78g of unreacted
t(n-Bu3P)Co(C0 )3 ]2Hg. When the solvent was changed to acetone, a 42
brown band started to move, but it slowly decomposed on passage down
the column. (The infrared spectrum of this material did not exhibit
bands for SO2 , so it was not further characterized.)
Attempted Reaction of NagSzOt and ri°-C5HBFe(C0 )2Cl
A slurry containing 0.8g (4 mmol) of n’-CsH3Fe(C0 )2 Cl and 0.7g
(3 mmol) of NazSzO* in 75 mL of CHgOH was stirred for 24 hours at 25°C.
Although the solution darkened considerably, an aliquot examined by thin layer chromatography indicated that [ri®-C5H 5Fe(C0 )2 S0 2 ]z did not form. The CHgOH was removed by rotary evaporation, and CH2CI2 was added to the residue. The mixture was applied to a 1.7 x 25 cm grade
III alumina column which was packed in CH2CI2 . Elution with CH2 CI2 initially moved a red band which yielded 0 .2 g of ri^-CsH5Fe(C0 )2Cl after evaporation of the solvent. Elution with CH2CI2 !acetone (v/v) 1:1 moved a band which afforded 0 .2 g of an unidentified material showing no peaks in the infrared spectrum which were attributable to the presence of SO2 •
IR (Nujol) 2020(sh), 1980(s), 1950(sh), 1815(sh), 1800(sh), 1760(s), 1040(m), 970(m), 830(w), 640(m) cm“^
Continued elution with acetone afforded 0.03g of
[r\^~CsEsFe(CO)] 2 (CO)(SOs) after workup. This product was identified by infrared spectroscopy.
Attempted Reaction of TI2 S2O4 and n°-C5H 5Fe(C0 )2Cl
A slurry of 0.579g (1.24 mmol) of TI2 S2O 4 and 0.530g (2.62 mmol) of n^-C5H 5Fe(C0 )2CI in 75 mL of CH3OH was stirred for 17 hours at 25°C.
An aliquot which was examined by thin layer chromatography showed that
[ri’-C5H 5Fe(C0 )2 S0 2 ] 2 did not form. The CH3OH was removed under reduced 43
pressure. Work-up of the resulting residue by chromatography on a
1.5 X 9.5 cm grade III alumina column afforded 0.041g of
[n'-CsHsFeCCO):]:, O.OlSg of n^-CsHsFe(CO)aCl, Q.06g of
[n^-CsHsFeCCOalaSOa, and 0.025g of [n®-C5H 5Fe(C0 ) ] a (CO) (SOa) ,
respectively, as the polarity of the eluting solvent was slowly
increased by addition of acetone to CHaCla. The products were
identified by infrared spectroscopy. Some brown decomposition material
remained at the top of the column.
Attempted Reaction of NaaSaO^ and [ri°-C5H 5Fe(CO)aHaO]BFj:,
Passage of Oa through a solution composed of 0.45g (1.3 mmol) of
[r)“-C5H 5Fe(C0 )a]2 and 0.48g (2.5 mmole) of 48% aqueous HBF^ in 16 mL of acetone caused the solution slowly to change from purple to red.
When the solution was bright red, O.lg (0.5 mmol) of NaaSaO<. was introduced, and the resultant solution was stirred for 15 minutes.
An aliquot of the solution revealed the absence of [r|“-C5H 5Fe(C0 )aS02 ] a upon examination by thin layer chromatography. The volatiles were removed from the reaction mixture under reduced pressure and the resultant residue was treated with CH2CI2 . The mixture was added to a
2 X 8.5 cm Florisil column, and elution with CHCI3 tacetone (v/v) 6:1 only moved one long yellow band. The band was collected and the solvent was evaporated from it to yield an orange solid. The infrared spectrum did not exhibit any SO2 bands, so the material was not further identi fied.
IR (Nujol) 1980(s), 1940(s) cm"" 44
Reaction of [n^-CsHsFeCCOÏaTHFjBFt and N&2 S
A slurry of 0.06g (0.7 mmol) of NagS in 60 mL of CH3OH was added dropwise to a solution of 0.58g (1.7 mmol) of [ri®-C5HsFe(C0)2THF]BFi,
(69) in 20 mL of THF. The solution immediately darkened from a bright red to a deep purple color. After the solution had stirred for 6 hours at 25°C, it was filtered to remove a small amount of a black precipi tate. The filtrate was taken to dryness by rotary evaporation. The resulting material was extracted with 50 mL of acetone, and filtration of the extract removed O.lg of a white solid. Addition of 20 mL of cyclohexane to the filtrate, and concentration of the solution to 4 0 mL afforded 0.2,82g of brown crystals of a species with an approximate formulation of [n^-C5H5)sFe3S(C0) ]BFi, (n = 4 or 5). n Melting Point 190°C (dec. - orange material sub limed onto walls of capillary tube)
Analytical Data Found: 39.16% C, 2.40% H, 27.30% Fe, 5.33% S Ratio of C/H/Fe/S = 20/14.6/3/1
IR(CH3CN) 2052(s), 2032(s), 2018(s), 1984(s), 1830(w) cm-i
IR(KBr) 3135(w), 2055(s), 2020(s), 1990(s), 1830(m), 1430(m), 1114(sh), 1088(s), 1052(s), 1040(sh), 1015(m), 854(m), 612(m), 578 (s), 344(s) cm"^
‘H NMR(CD3CN)t 5 .2 0 , singlet, relative intensity 6 5.33, singlet, relative intensity 2 5.49, singlet, relative intensity 1
“ C NMR(CD3CN) 214.814 ppm, CO 90.809 ppm, CsHs (minor) 90.005 ppm, CsHs (minor) 89.493 ppm, C5H 5 (major)
Mass Spectrum See Table in the Appendix 45
B. Reactions of the Organometallic Dlthionite Complexes
Reaction of [n°-C5 H5 Fe(C0 )2 S0 2 ]g and Alkyl Halides
In a general reaction [ri^-CsHsFe (0 0 )2 8 0 2 ] 2 and a large excess of
the alkyl halide were maintained at reflux for 3 hours in 30 mL of THF.
The quantities of each reactant are listed in Table 1. After the
reaction solution cooled to room temperature, a small amount of
insoluble material was removed by filtration. The filtrate was taken
to dryness by rotary evaporation and a red oil resulted.^ This oil was extracted into 10 mL of CHCls and the extract was chromatographed on a 2 x 10 cm grade III alumina column. The products are listed in
Table 1 in the order of elution with CHCI3 . The two products, n^-CsHsFe(0 0 ) 2 1 and [ri^-C5 HsFe(C0 )2 ]2 , were identified by infrared spectroscopy by comparison with the spectra of authentic samples.
Complexes of the type ri®-CsH5 Fe(C0 )2 S(G)2 R were identified by comparison of the NMR and IR spectra obtained for the products with the spectra reported for the known compounds (81).
Reaction of [n^-CsHsFe(CO) 2 8 0 2 1 2 and (C2H 5 )3 0 PF6
A solution of 0.24g (0.50 mmol) of [r)^-C5 H 5 Fe(C0 )2 8 0 2 ] 2 and 0.12g
(0.50 mmole) of (C2Hs)aOPF6 in 30 mL of CH2 CI2 was stirred at 25°C for
1.5 hours. During this time the solution slowly darkened from orange to red-purple. Upon concentration of the solution to 15 mL a red precipitate formed which was collected by filtration (0.03g). The
When [r)*-CsHsFe(CO)2 8 0 2 ) 2 and CH3I reacted, a NMR spectrum (CDCI3) of this red oil showed that ri’“C3 H 5 Fe(C0 )2 l and n*“C 5H 5 Fe(C0 )2 8 (0 )2 CH3 (81) were both present. TABLE 1
REACTIONS OF [n^-CsHsFeCCO)2 SO2 ]2 AND RX
Reactants Amount(mmol) Products Yield (%)
1 ) [n’-CsH5Fe(C0)2S02]2 0.205 g (0.43) A) n=-C5H5Fe(C0)2l 0,148 g (40%)
and CH3 I 2 ml (55.8) B) n“-C5 H 3 Fe(C0 )2 SO2 CH3 0.048 g (2 2 %)
C) (n “CsHs)2 Fe2 (CO)3 (SO2 ) 0 . 0 0 2 g ( 1 %)
2 ) [n=-C,H5Fe(C0)2S02]2 0.207 g (0.43) A) n=-CsH5Fe(C0)2l 0.145 g (39%)
and C 2 H 5 I 2.5 ml ( 31) B) n=-CsHsFe(CO)2 SO2 C 2 H 5 0.047 g (2 0 %)
3) [n*-C,H5Fe(C0)2S02]2 0.165 g (0.34) A) n=-CsH3Fe(C0)2l 0.124 g (60%)
and CH3 CH(I)CH3 3 ml ( 26) B) rf-C5HsFe(C0 )2 S0 2 CH(CH3 ) 2 0.016 g ( 8 %)
4) [n’-CsH5Fe(C0)2S02]2 0 . 1 2 0 g (0.25) A) [rf-CsH3Fe(C0)2]2 0.068 g (77%)
and C 2HsBr 3 ml ( 39) B) (n —CsHs)2Fe2 (CO)3 (8 0 2 ) 0.015 g (15%)
5) [n’-CsHsFe(0 0 )2 8 0 2 ] 2 0.144 g (0.30) A) [n=-CsHsFe(C0 )2 ] 2 0.064 g (62%)
and CH3 CH(Br)CH3 3 ml ( 35) B) (n^-CsHs)2Fe2(C0)3(S02) 0 . 0 1 0 g ( 9%)
o\ 47
infrared spectrum of the red material showed that SO2 was not present,
and the material was not identified further.
IR (Nujol) 2070(s), 2010(s), 840-20(s) cm"^
"H NMR(CD3 CN)t 4.55, singlet, C 5H 5
The filtrate from above was evaporated to a red oil. An NMR
spectrum (CDCI3) of this oil exhibited resonances for four different
ri’-CsHsFe compounds.
NMR(CDCl3 )T 4.42, singlet, C5H5 4.66, singlet, C 5 H 5 4.71, singlet, C5 H 5 4.77, singlet, CsHs 5.66, quartet, (J=7Hz), -CH2 - 8.77, triplet, (J=7Hz), -CH3-
The oil was extracted with 15 mL of CHCI3, and the extract was
added to a 1 x 20 cm Florisil chromatography column. Elution with
CHClsiacetone (v/v) 5:1 moved only one band down the column. After
collection of this yellow band and concentration, a yellow solid,
identified as T^-CsHsFe(C0 )2 S(0 )2 0 C2 Hs (82), 0.038g (27%), was isolated.
The characterization of n^-CsHsFe(C0 )2 S(0 )2 0 C2Hs is fully described on
page 55.
Attempted Reaction of [(C0 )sMnS0 2 ] 2 and CH3I
On the vacuum line 15 mL (0.84 mole) of CH3I was condensed onto
0.20g (0.30 mmol) of [(C0 )sMnS0 2 ] 2 in a glass reaction bulb. The contents of the bulb were heated at 80“C in a closed system for 3 hours.
When the reaction mixture had cooled to room temperature, it was decanted to a flask, and the reaction bulb was rinsed with three 20 mL aliquots of acetone. The washings and decantate were combined, and the volatiles were removed by rotary evaporation. The residue was treated 48 with 25 mL of THF, and filtration of the mixture removed 0.020g of a brown material which was not identified. The infrared spectrum for
it is recorded below.
IR (Nujol) 2120(m), 2035(s), 2010(s), 1960(m), 1145(br. from 1250 to 820), 625(s) cm-i
When the filtrate was taken to dryness, 0.165g of unreacted
[(C0 )5MnS0 a]2 was collected.
Thermolysis of [(C0 )sMnS0 2 ] 2
In a sublimation apparatus 0.2g of [(C0 )5MnS0 2 ]2 was heated at
74°C/1 torr for 2 hours without any change. However, after treatment for 2 hours at 97°C/1 torr, the material slowly darkened from yellow to orange. The orange solid was not identified, but the infrared spectrum of it lacked any sharp S-0 stretches.
IR (Nujol) 2100(m), 2025(s), 2010(s), 1970(m), 1175(br,m), 910(br,m), 635(s), 615(s) cm“ ^
Mass Spectrum (100°C) The material was insufficiently volatile for a mass spectrum.
Photolysis of [ri°-C5 H 5 Fe(C0 )2 S0 2 ]2
1. In the apparatus shown in Figure 1 a solution of O.lOg (0.21 mmol) of [ri®-CsH5 Fe(C0 )2 S0 2 ] 2 in 45 mL of THF was photolyzed for 15 minutes with 3500 A lamps under slow CO purge. The color slowly changed from orange to red-brown. The mixture was decanted into a flask, and the solvent was removed by rotary evaporation. After the reaction residue was placed on a 2.7 x 13 cm Florisil column with a small amount of CHCI3, elution with CHCI3 moved a red band which contained 49
[ri*-C3 HsFe(C0 )2 ]2 » O.Olg (13%). Elution with CHClazacetone (v/v) 1:1
removed a trace amount of [ri“-CsH5 Fe(C0 )aS0 2 ]2 . Methanol was required
for elution of a third, red band. After collection and concentration
of the band 0.023g (26%) of [ri*-CsHsFe(C0 )2 ]2 S0 2 was recovered.
2. In a second experiment, irradiation under the same conditions
as above for one hour led to decomposition materials which were not
identified. Chromatography of the reaction mixture failed to isolate
species such as [ri®-CsHsFe(G0 )2 ]2 , [n^-CsHsFe(CO)2 )2 3 0 2 , or
[^^“CsHsFe(CO)2 SO2 ]2 .
Photolysis of [(CO)gMnSOa]2
1. In the apparatus shown in Figure 1, 0.09g (0.2 mmol) of
[(CO)gMnSOa]2 in 40 mL of THF was photolyzed for 10 minutes with 3500 A
irradiation. During the course of the reaction the solution changed
from a light yellow to orange color. The mixture was transferred to a
flask, and the THF was removed under reduced pressure. The yellow-brown residue was extracted with 20 mL of benzene, and the resulting mixture was filtered to separate a yellow-brown solid from a yellow solution.
The solid was treated with benzene until the washings were clear. The washings and filtrate were combined, and the benzene was removed by rotary evaporation. An infrared spectrum (Nujol) of the resulting residue identified it as Mn2 (C0 )io, 0.02g (30%).
The yellow-brown solid from above was treated with 10 mL of
CH3CN, and filtration of the resulting mixture separated an orange solution from a small amount of a white solid. Removal of CH3CN from the filtrate afforded 0.045g (50%) of [Mn(C0 )sS0 2 ]2 • 50
2. When 0.08g of [Mn(CD)sS0 2 ] 2 was irradiated in the same fashion
as above for one hour, O.OlBg (30%) of Mna(CO)io was the only identifiable
product recovered. A brown material (0.024g) was also produced, but an infrared spectrum of it failed to exhibit any S-0 stretches.
IR (Nujol) 2150(w), 2050 (s), 2040(s), 1990 (s), 1940 (s), 1180 to 980(w,br), 630(s) cm“ ^
Attempted Reaction of [r]^-C5 H 5 Fe(C0 )2 S0 2 ] 2 and KH
In a glove box 0.063g (1.6 mmol) of 93% KH was added to 0.44g
(0.90 mmol) of [n^-CsH5 Fe(C0 )2 S0 2 ] 2 in a 3 x 15 cm Pyrex reaction tube which could be attached to the vacuum line. After transfer of the tube from the glove box to the vacuum line 15 mL of THF was condensed onto the solids at -78°C. The solution was stirred for one.hour, but an attached manometer indicated that no gas (H2 ) was evolved. The reaction mixture was then stirred for one hour at -30°C (1,2 dichloro- ethane slush bath). Again, the attached manometer failed to register an increase in pressure. The solution was then allowed to warm to 23°C, and it was stirred for an additional 5.5 hours. The manometer did register a pressure increase, but it apparently was due to the vapor pressure of THF. The THF was removed under reduced pressure, and the reaction apparatus was sealed off and taken into the glove box. An infrared spectrum (Nujol) showed the presence of only unreacted
[n=-C5H,Fe(C0)2S02]2.
Reaction of [n*-CaH5 Fe(C0 )2 S0 2 ] 2 and Na/K2 .a
A slurry of 0.192g (3.98 mmol) of [n'-CjHsFe(0 0 )2 8 0 2 ] 2 in 30 mL of THF in a round-bottom flask which had a 250 mL evacuated gas bulb 51
attached to it was treated (via syringe) with 0.2 mL of Na/Kz.g. The
reaction system was isolated and stirred for 16 hours at 25°C during
which time the [tl^-C5 H 5 Fe(C0 )aS0 2 ] 2 dissolved and reacted to give a
red-purple solution. The evacuated bulb was opened to the system in
order to collect any evolved gases. The solution was filtered into
another flask by the polyethylene filter-tube technique (60). The
filtrate was taken to dryness to produce a red solid.
IR (Nujol) 2030(sh), 1990(sh), 1970(s), 1760(s), 1262(m,br), 1 1 1 0 (s,hr), 1 0 2 0 (s,br), 795(s,br)
NMR((CD3 )2 C0 ) 4.77, C5 H5 , relative intensity 1 4.95, C 5 H 5 , relative intensity 4 5.18, CsHs, relative intensity 5.5
The mass spectrum (25°C) of the gas sample showed peaks for only
THF and not SO2 .
C. Preparation and Characterization of Alkysulfito Organometallic
Complexes
Exchange of Na[S(0 )2 0 R] with R'OH
1. Exchange of Na[S(0 )2 0 CHg] and C2HSOH
After a solution of 0.512g of Na[S(0)2 OCH3 ] in 40 mL of C^HsOH had stirred at 25°C for 24 hours, the solvent alcohol was removed under reduced pressure. The white solid was dissolved in D 2 O, and an ^H NMR spectrum of the solution showed very strong resonances for
Na[S(0 )2 ÛCH2Hs] and a very weak peak for unreacted Na[S(0 )2 0 CH3 ].
^H NMR(D2 0 )t'* 6.25, quartet, Na[S(0 )2 ÛCH2 CH3 ] (2) 8.70, triplet, Na[S(0 )a0 CH2 CH3 j (3) 6.53, singlet, Na[S(0 )2 ÛCH3 ]
Based on T„ . = 5.20 rl2Ü 52
2. Exchange of Na[S(0 )2 0 C 2Hs 3 and CH3OH
After a solution of 0.527g of Na[S(0 )aOCaH5 ] in 40 mL of CH3OH had
stirred for 24 hours at 20°C, the methanol was removed under reduced
pressure. The white solid was dissolved in D 2 O, and the NMR spectrum
showed complete conversion to Na[S(0 )2 0 CH3 ].
NMR(D2 Û)t^ 6.56, singlet, NaESCOaOCHs]
Preparation of n'-CsHsFeÇCOÏaSCOjaOCHs
1. From Reaction of [n^-CsH5 Fe(C0 )2 H 2 0 ]BFi, and Na[S(0 )2 0 CH3 ]
As O2 was bubbled through a solution of l.OOg (2.83 mmol) of
[ri®-C5 H 5 Fe(C0 )2 ] 2 and 1.05g (6.00 mmol) of 48% aqueous HBF^ in acetone, the solution slowly changed from purple to bright red in color. When the oxidation was complete (bright red solution), the acetone and H 2 O were removed from the reaction by rotary evaporation to give a dark red-purple oil. The oil was dissolved in 70 mL of CH3OH, and 0.8g
(7 mmol) of Na[8 (0 )2 0 0 1 1 3 ] was added to the solution. As the solution was stirred for 12 hours at 25°C, it slowly changed color from red to yellow. After removal of CH3OH under reduced pressure the residue was extracted with 30 mL of CHCI3. The extract was applied to a 3.7 x 13 cm Florisil column, and elution with CHCI3tacetone (v/v) 5:1 developed a long yellow band which was collected and concentrated to 15 mL.
Addition of 30 mL of cyclohexane with stirring afforded yellow crystals of n'-C3 HsFe(C0 )2 S(0 )2 0 CH3 , 0.781g (50.7%).
Melting Point 156°C (dec.)
‘H NMR (CDCl3 )T 4.79, singlet, C5 H, (5) 6.41, singlet, CH3 (3)
* Based on * 5.20 53
IR(KBr) 3106(m), 3016(vw), 2982(vw), 2942(m), 2904(vw), 2830(vw), 2064(vs), 2007(vs), 1988(sh), 1462(vw), 1426(m), 1214(vs), 1173(sh), 1095(vs), 1061(s), 995(sh), 971(vs), 913(lu), 8 6 8 (m), 836(vw), 6 8 6 (s), 636(s), 604(s), 579(s), 558(s), 566(m) cm“^
Mass Spectrum See Table in the Appendix
2. From Reaction of [r)®-C5 HsFe(C0 )2 S0 2 ]BFi, and CH3OH
In the glove box 1.40g (7.20 mmol) of AgBFz, and 2.17g (7.20 mmol)
of n^-C5 H 5 Fe(C0 )aI were added to a 100 mL round bottom flask. The
flask was removed from the glove box, and a dry ice condenser was
attached to it. After 30 mL of liquid SO2 was condensed onto the
solids, the resultant solution was maintained at reflux, -10°C, for 8 hours, during which time it changed color from dark purple to a bright
red. To remove the precipitated Agi the reaction mixture was filtered at -78°C with the polyethylene filter-tube technique (60). After 15 mL of CH3OH was syringed into the red filtrate, the resulting solution was slowly warmed to 25“ over 12 hours, during which time the SO2 boiled off. Evaporation of the solvent under reduced pressure yielded a red- brown oil. The oil was extracted with CH2CI2, and the extract was chromatographed on a 1 x 25 cm Florisil column. An orange band was observed to precede a dark red band. The orange band was collected and evaporated to dryness to afford 0.233g of ri®-CsH5 Fe(C0 )2 S (0)2OCH3. The dark red band was then collected and concentrated to a red oil. The red oil was rechromatographed with CH2 CI2 :acetone (v/v) 5ll on a 2.7
X 15 cm Florisil column. Elution produced a long yellow fraction which separated from an immobile orange band at the top of the column. The 54
yellow band was collected and concentrated to afford an additional
0.33g of n®-C5 HsFe(C0 )aS(0 )2 0 CH3 . Total yield: 0.57g (29%).
3. From Reaction of K[ri®-CsH5 Fe(C0 )2 S0 2 ] •%S0 2 and CH3SO3F
In the glove box 4.1g (14 mmol) of K[ri’-C5H 5 Fe(C0 )2 S0 2 ] •%S0 2 was
added to a 250 mL round-bottom reaction flask. The flask was with
drawn from the glove box, and 1.8g (16 mmol) of CH3SO3F and 100 mL
of CH2 CI2 were introduced. As the solution was refluxed for 2 hours,
it lightened in color from orange to yellow-orange.
After the reaction mixture had cooled to 25°C, the volatiles were
removed at 25°C/1 torr overnight. The resulting orange residue was
treated with 70 mL of ethyl acetate, and the extract was eluted on a
3.1 X 40 cm Florisil column with ethyl acetate. Initially, a small
purple band of [r^-C5 HsFe(C0 )2 ] 2 was collected and discarded.
Continued elution produced a long yellow-orange band which was
collected and concentrated to dryness. The residue was dissolved in
60 mL of CHCI3 and cyclohexane was added until the solution became
cloudy. The solution was concentrated by rotary evaporation until
orange crystals appeared. Filtration of the solution resulted in
collection of 0.33g (5.0%) of [ri“-CsH5 Fe(C0 )2 S0 2 ]2 . Evaporation of
the solvent from the filtrate gave ri®-CsH5 Fe(C0 )2 S(0 )2 0 CH3 , 0.86g (23%).
4. From Reaction of K[r)®-CsH5 Fe(CG)2 S0 2 ]*%'S0 2 and (CH3 )3 0 PF6
In the glove box 3.88g (12.4 mmol) of K[ri®-C5 HsFe(C0 )2 S0 2 ]*%S0 2 was added to a 250 mL round-bottom flask. The flask was removed from
the box and charged with 2.00g (14.1 mmol) of (CH3 )3 0 FF6 , 125 mL of
CH2 CI2 , and 5 mL of nitromethane. After the solution had refluxed for 55
3 hours, the volatiles were removed overnight on the vacuum line at
25°C/1 torr. The resultant orange solid was treated with ethyl
acetate and the mixture was chromatographed on a 1.5 x 80 cm Florisil
column with ethyl acetate. A small purple band of [ri^-CsH5 Fe(CG)2 ] 2
was initially collected and discarded. A long yellow band was then
collected, and the ethyl acetate was removed from this fraction by
rotary evaporation. After dissolution of the residue in 30 mL of
CHCls, addition of 30 mL of cyclohexane induced crystallization of
0.140g (4.49%) of [n^-C5 HsFe(C0 )2 S0 2 ] 2 which was collected by filtration.
Evaporation of the filtrate to dryness afforded a yellow powder of
ri“-CsHsFe(C0 )2 S(0 )2 0 CH3 , 0.105g (2.03%). A large amount of brown
decomposition material remained at the top of the chromatography column.
Preparation of r|^-C5 H 5 Fe(C0 )2 S(0 )2 0 C2 H 5
1. From Reaction of [ri“-CsHsFe(C0 )2 H 2 0 ]BFi, and Na[S(0 )2OC2H5]
As O 2 was passed through a solution of 2.00g (5.65 mmol) of
[ri*-C5 H 5 Fe(C0 )2 ] 2 and 2.10g (12.0 mmol) of 48% aqueous HBF4 in 100 mL
of acetone, the solution slowly changed color from purple to red. When
the oxidation was complete (bright red solution), the acetone and H 2 O were removed by rotary evaporation to give a purple-red oil. The oil was dissolved in 120 mL of C2H5OH and 1.77g (14.4 mmol) of
Na[S(0)2 OC2HS] was added to the solution. As the solution was stirred
for 12 hours at 25°C, it slowly changed color from red to yellow-brown.
The C2H3OH was removed by rotary evaporation, and the resultant yellow- brown residue was extracted with CHCI3 . Chromatography of the extract on a 2.7 x 20 cm Florisil column with CHCl3 :acetone (v/v) 5:1 developed 56
a yellow-orange band. After this band was collected, concentration
of it produced a yellow-brown oil. Dissolution of the oil in 20 mL
of CHCla, followed by addition of 40 mL of cyclohexane, afforded yellow crystals of Ti®-C5 HsFe(CO)2 S(0 )2 0 C2 H 5 , 1.67g (51.0%).
Melting Point 96°C
Analytical Data Calc, for CgHioFeOsS; 37.87% C, 3.52% H, Found, 37.17% C, 3.46% H
NMR (CDCl3 )T 4.60, singlet, C5 H 5 (5) 5.99, quartet (J = 7Hz), -CH2- (2) 8.77, triplet (J = 7Hz), -CH3 (3)
IR(KBr) 3120(m), 2110(sh), 2984(w), 2960(vw), 2938(w), 2906(w), 2872(vw), 2062(vs), 2000(vs), 1478(vw), 1434(m), 1424(sh), 1388(w), 1366(vw), 1214 (s), 1156(vw), 1105(sh), 1088(s), 1020(s), 971(sh), 904(s), 891(m), 869(s), 839(m), 731(s), 676(vw), 615(s), 592(s), 578(s), 568(s), 524(vw), 505(m), 494(sh) cm“ ^
Mass Spectrum See Table in the Appendix
2. From Reaction of [n^-CsHsFe (CO) 2 H 2 0 ]BFz,, Na2S03, and C2H5OH
As O 2 was passed through a solution containing 2.00g (5.65 mmol) of [r^-C5 HsFe(C0 )2 ] 2 and 2.10g (12.0 mmol) of 48% aqueous HBF^ in 100 mL of acetone, the solution slowly changed color from purple to red.
When the oxidation was complete (bright red solution), the acetone and
H 2 O were removed by rotary evaporation to yield a red oil. The oil was dissolved in 150 mL of C2 H 5 OH and 2.5g (20 mmol) of Na2 S0 3 was added to the resulting solution. Because of the apparent low solubility of Na2 S0 3 in C2 H 5 OH, the mixture was stirred for 3 days at
25°C, during which time the solution slowly changed color from red to 57 yellow. The solution was evaporated to dryness, the yellow residue was extracted with 100 mL of CHCI3 , and the extract was filtered to remove some insoluble material (NagSOg, NaBFi,). The filtrate was chromatographed on a 2.7 x 15 cm Florisil column with CHCla:acetone
(v/v) 5:1. The first band which passed down the column contained
0.020g (1.0%) of [n^-CsH5 Fe(C0 )2 ]2 . The second band which was developed contained 1.29g (40.0%) of n*-C5 HsFe(C0 )2 S(0 )2 0 C2 Hs.
Preparation of n^-CsH5 Fe(C0 )2 S(0 )2 0 CH2 CH2 CH3
As O2 was passed through a solution of l.OOg (2.83 mmol) of
[r)^-CsHsFe(C0 )2 ] 2 and 1.05g (6.00 mmol) of 48% aqueous HBF^, in 75 mL of acetone, the solution slowly changed from purple to red. When the oxidation was complete (bright red .solution), the acetone and H 2 O were removed by rotary evaporation. The resulting red oil was dissolved in
100 mL (1.3 mol) of I-C3H7OH, and 0.86g (6.5 mmol) of Na[S(0)2 OC2 HS] was added to this solution. After stirring for 16 hours at 25°C the
I-C3H7OH was removed by rotary evaporation to produce a dark yellow solid. The solid was extracted with CHCI3 and the extract was charged to a 2.7 X 25 cm Florisil column. Elution with CHCI3:acetone (v/v)
5:1 moved a single orange band. This fraction was evaporated to dryness to yield a yellow powder of n®-CsHsFe(C0 )2 S(0 )2 0 CH2 CH2 CH3 , 0.82g (48%).
Melting Point 94-96°C
"H NMR (CDCl3 )T 4.68, singlet, C5 H 3 (5) 6.14, triplet (J = 6 Hz), -CH2CH2CH3 (2) 8.14, multiplet (J = 6 Hz, J' = 6 Hz), -CH2CH2CH3 (2 ) 9.08, triplet (J' = 6 Hz), CH3 (3) 58
IR(KBr) 3112(m), 2966(m), 2938(m), 2992(sh), 2890(w), 2828(sh), 2068(s), 2052(sh), 2014 (s), 1435(vw), 1427(m), 1418(m), 1388(w), 1249(m), 1211(vs), 1158(vw), 1087(vs), 1060(vw), 1050(sh), 1013(w), 993(w), 973(m), 940(m), 906(w), 873(w), 835(vw), 793(m), 733(m), 709(m), 672(w), 639(m), 608(m), 574(m), 558(m), 520(w), 515(sh), 490(vw) cm'— 1
Mass Spectrum (120°C) /e = 354 for [Ti®-CsH5 Fe(C0 ) a ] 2 (10) /e = 326 for (n'-CsHs)2 Fea(0 0 )3+(4) /e = 298 for (n'-C,H,)2 Fe2 (C0 )a+ (8 ) “ /e = 186 for (C5 Hs)2 Fe+ (1 0 0 ) /e = 177 for n=-C,H,Fe(C0 )2+ (38) m /e = 64 for 8 0 2 '^ (100)
Preparation of n^-CsHsFe (CO)2 8 (0 )2 0 0 1 1 (0113)2
As O 2 was bubbled through a solution of 2.00g (5.65 mmol) of
[Tl®-C5 H 5 Fe(CG) 2 ]2 and 2.10g (12.0 mmol) of 48% aqueous HBF* in 150 mL of acetone, the solution slowly changed color from purple to red.
When oxidation was complete (bright red solution), the acetone and
H 2 O were removed by rotary evaporation. The resultant oil was dissolved in 150 mL (2.00 mol) of 2 -C3 H 7OH and 1.80g (13.5 mmol) of Na[S(0 )2 0 C 2 H 5 ] was added to the solution. The solution was stirred for 12 hours at
25°C and then the reaction mixture was evaporated to dryness. The yellow residue was dissolved in CHCI3 , and elution on a 2.7 x 25 cm
Florisil column with CHCI3 racetone (v/v) 5:1 produced an orange band which yielded 1.09g (32.4%) of r|“-C5H 5 Fe(C0 )2 S(0 )2 0 CH(CH3 ) 2 upon evaporation to dryness.
Melting Point 164-65°C (dec.) 59
NMR (CDClg)! 4.83, singlet, CsHs (5) 5.10, septuplât (J = 6.1Hz)®, CH (1) 8.25, doublet (J = 6.1Hz), CHa (6 )
IR(KBr) 3120(m), 2990(sh), 2978(s), 2930(w), 2070(s), 2052(sh), 2010(s), 1420(m), 1401(m), 1370(w), 1352(w), 1342(w), 1211(s), 1208(sh), 1178(w), 1112(s), 1084(s), 1065(m), 918(s), 865(sh), 845(s), 718(m), 640(s), 606(m), 581(s), 560(m), 524(m) cm“ '
Mass Spectrum (120°C) ™/e = 186 for (CsH5 )2 Fe^ (44) /e = 177 for n^-CsHsFefCO):* (34) “Ve = 1 2 1 for n=TCsHsFe+ (100) ™/e = 64 for SO2+ (70)
Attempted Preparation of n -C5H 5 Fe(C0 )2 S(0 )2 0 C6 H 5
As O2 was bubbled through a solution of 2.00g (5.65 mmol) of
[n®-C5 HsFe(C0 )2 ]z and 2.10g (12.0 mmol) of 48% aqueous HBF4 in 150 mL of acetone, the solution slowly changed color from purple to red. When the oxidation was complete (bright red solution), the acetone and H 2 O were removed by rotary evaporation to produce a red oil. After 50 mL
(0.56 mol) of phenol (m.p. = 43°C) and 1.80g (13.5 mmol) of Na[S(0 )2 0 C2Hs] was added to the red oil, the resulting solution was stirred for 16 hours at 50-55°C. The reaction mixture was cooled to 25°C and most of the excess phenol was removed by extraction with 100 mL of CCI4 . The material which remained was dissolved in CHClg, and the solution was chromatographed with CHCI3 on a 2.7 x 30 cm Florisil column to remove the balance of the unreacted phenol. When the solvent was changed to
CHCI3:acetone (v/v) 5:1, elution produced a light orange band. The
Two component peaks of the presumed septuplet appear to overlap the CsHs resonance. 60
band was collected, and, after evaporation to dryness, 0.24g (1 1 %) of
r|®-CsHsFe(C0 )2 S(0 )2 0 C2H 5 was isolated.
Attempted Preparation of n^-CsHsFeCCO)(PPh3 )S(0 )2 0 CH3
1. From Photolysis of n^-CsHsFe(CO)2 8 (0 ) 2 0 0 1 1 3 and PPha in Benzene
A solution of 0.30g (1.4 nmol) of n*-CsHsFe(C0)aS(0)a0CHa and
0.40g (1.5 mmol) of PPhs in 50 mL of benzene was photolyzed with O 3500 A lamps for 1.5 hours. After 1.5 hours an infrared spectrum of the solution indicated that the ri®-C5 HsFe(C0 )2 S(0 )2 0 CH3 had been consumed (CO bands at 2064 and 2007 cm“^ had disappeared). The solution was filtered to remove a large amount of decomposition material (non carbonyl). The filtrate was evaporated to dryness to yield a brown residue. This material was extracted with CHCI3 and then chromatographed on a 1.5 X 10 cm Florisil column with CHCI3 to afford unreacted PPhs.
No other bands moved down the column even when acetone was used for elution.
2. From Reaction of ri*-CsH5 Fe(C0 )2 S(0 )2 0 CH3 , PPh3 , and (CH3 )3N0
When 25 mL of CHCI3 was added to a mixture of 0.27g (1.0 mmol) of n^-C5 HsFe(C0 )2 S(0 )2 0 CH3 , 0.26g (1.0 mmol) of PPh3 , and 0.079g (1.1 mmol) of (CH3 )2N0 , the solution immediately darkened from light yellow to brown and gas evolution was detectable. After stirring for 3 hours the volatiles were removed from the solution under reduced pressure.
The residue was taken up in CHCI3 and chromatographed on a 2.7 x 10 cm
Florisil column. Only unreacted PPhs and a small amount of ri®-CsHsFe(CO)2 8 (0 ) 2 0 0 1 1 3 were removed by elution with CHCI3 :acetone
(v/v) 5:1. 61
3. From Reaction of n’-CsHsFeCCO)(PPhg)! and Na[S(0 )a0 CH3 ]
A solution of 0.27g (0.99 mmol) of Na[S(0 )a0 CH3 ] and O.SOg (1.0 mmol) of ri“-CsH5 Fe(C0 )(PPh3 )I was refluxed in 50 mL of CH3OH for 3 hours.
In one hour the reaction mixture changed color from green to orange.
The CH3OH was removed by rotary evaporation, and the residue was
extracted with CHCI3, but very little material dissolved. Chromato graphy of the extract on a Florisil column with CHCI3 failed to move any identifiable bands down the column.
Preparation of CH3 0 S(0 )2Mn(C0 )3 (2,2-bipyridine)
A solution of l.OOg (3.02 mmol) of ClMn(CO)3 (2,2-bipyridine) and
0.420g (3.56 mmol) of Na[S(0 )2 ÛCH3 ] in 175 mL of CH3 OH was refluxed for four hours. The solution was filtered to remove a white precipitate
(NaCl). After the filtrate was evaporated to dryness by rotary evaporation, the resulting orange material was extracted with 500 mL of CHCI3 , and the extract was filtered to remove additional white insolubles. The filtrate was concentrated to 25 mL, and 1.05g (90.1%) of an air-stable, orange powder of CH3 0 S(0 )zMn(CO)3 (2,2-bipyridine) was collected by filtration.
Melting Point 166-168°C
^ NMR (DMSO)t 0.19-2.28, multiplet, CioHeNa (8 ) 7.33, singlet, CH3 (3)
IR(KBr) 3105(vw), 3070(w), 2980(vw), 2945(vw), 2054(s), 1940 (vs), 1465(m), 1435(m), 1310(m), 1243(vw), 1224(w), 1198(s), 1174(w), 1156(m), 1121 (w), 1106(w), 1077(s), 955(s), 912(w), 818(w), 780(s), 759(w), 736(m), 6 8 6 (m), 656(s), 642(s), 620(s), 526(m), 486(vw), cm-i 62
Attempted Preparation of Other Alkylsulfito Organometallic Complexes
1. Reaction of n®-CsHsCr(N0)2Cl and Na[S(0)a0CH3]
A solution of 0.401g (1.89 mmol) of ri®-CsHsCr(N0)2C1 and 0.33g
(2.8 mmol) of Na[S(0)20CH3] in 35 mL of CH3OH was refluxed for 3 hours
with no apparent color change. After the CH3OH was evaporated, the
solid which resulted was extracted with CHCI3, and filtration of the
extract separated a white powder from a green filtrate. The CHCI3 was
removed from the filtrate, and the green solid which was recovered was
identified by infrared spectroscopy as unreacted ri^-CsHsCr(N0 )2 C1 ,
0.38g (96%).
2. Reaction of [Mn(C0)sCH3CN]PF6 and Na[S(0)20CH3]
A solution composed of l.OOg (2.59 mmol) of [Mn(C0)5CH3CN]PF6 and
0.447g (3.78 mmol) of Na[S(0)20CH3] in 30 mL of CH3OH and 10 mL of acetone was maintained at reflux for 3 hours. After the CH3OH and acetone was evaporated, the solid which resulted was extracted with
CHCI3, and the mixture was filtered to separate a white powder from a yellow filtrate. When the CHCI3 was removed from the filtrate by rotary evaporation, 0.89g (89%) of [Mn(CO)sCHsCNjPFg was recovered.
3. Reaction of ClMn(CO)3 (PPhs) 2 and Na[S(0 )2 ÛCH3 ]
A solution of 1.45g (2.07 mmol) of ClMn(CO)3 (PPhs) 2 and 0.300g
(2.54 mmol) of Na[S(0 )2 0 CHs] in 35 mL of CH3OH was kept at reflux for
4 hours. After the CH3OH was evaporated, the solid which resulted was extracted with CHCI3, and the mixture was filtered to remove a trace amount of a white powder from an orange filtrate. When the
CHCI3 was removed from the filtrate by rotary evaporation, 1.38g
(89.7%) of ClMn(C0 )3 (PPhs)2 was recovered. 63
4. Reaction of [(n-Bu)i,N] [W(CO)sI] and Na[S(0 )aOCH3 ]
A solution composed of 2.99g (4.30 mmol) of [(n-Bu)4 N][W(C0 )sI] and l.Q2g (8.64 mmol) of Na[S(0 )a0 CH3 ] in 90 mL of CH3OH was kept at reflux for 3 hours, during which time it changed color from yellow to light green. After the CH3OH was evaporated, the solid which resulted was extracted with CHCI3, and the mixture was filtered to separate a small amount of a white solid from a light green filtrate.
When the CHCI3 was removed from the filtrate by rotary evaporation,
[ (n-Bu)i,N] [W(CO)sI] was recovered, 0.233g (77.9%).
D. Reactions of the Alkylsulfito Ligand in ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 R
Hydrolysis
Preparation of ri^-C5 H 5 Fe(C0 )2 S (0 )2 0 H
A solution of 0.646g (2.26 mmol) of n®“CsHsFe(C0)aS(0)a0CaHs in
30 mL of H 2 O was stirred for 16 hours at 25°C.® The excess water was removed on the vacuum line at 25°C/1 torr. The resultant yellow solid was dissolved in 200 mL of CH3CN, and the solution was filtered to remove a trace amount of a white material from a yellow filtrate.
Concentration of the filtrate afforded a yellow, air-stable material identified as rf-C5HsFe(C0 )2 S(0 )2 0 H, 0.546g (93.6%).
Melting Point 104°C
Analytical Data Calc, for CyHgFeOsS: 32.58% C, 2.34% H Found: 32.79%, 2.51% H
This hydrolysis is general for the R = CH3, C2H5, CH2CH2CH3, and CH(CH3 ) 2 alkylsulfito complexes, ri*“C5 HsFe(C0 )2 S(0 )2 0 R. 64
NMR (DMSO)t 4.70, singlet, C5 H 5 (5) -1.16, broad singlet, H (1)
IR(KBr) 3022(m), 2940(w,br), 2510(w,br), 2062(vs), 2018(vs), 1434(m), 1423(m), 1275(m,br), 1185(s), 1084(m), 1066(sh), 1038 (s), 1005 (sh), 859(s), 839(w), 811 (s), 610(sh), 601(sh), 588(s), 567(s), 548(s), 487(m), 466(m) cm“ ^
Mass Spectrum The material had insufficient volatility for a mass spectrum.
Preparation of ri°-C5 H 5 Fe(C0 )2 S(0 )2 0 D
In the same fashion as above, 0.455g (1.67 mmol) of
ri®-CsH5 Fe(C0 )2 S(0 )2 0 CH3 was converted to 0.401g (92.7%) of
n®-C5 H 5 Fe(C0 )2 S(0 )2 0 D by hydrolysis with D 2 O.
IR(KBr) 3122(m), 2510(w,hr), 2440(w), 2230(w,hr), 2062(vs), 2016(vs), 1432(m), 1418(ra), 1275(m,hr), 1212(s), 1185 (s), 1080(sh), 1066(sh), 1038(s), 1005(sh), 859(m), 840(w), 807(s), 603(sh), 598(sh), 583(sh), 563(s), 545(s), 483(m), 461(m) cm~^
Transestérifications
1. Acid Promoted
Reaction of n°-C5 H 5 Fe(C0 )2 S(0 )2 0 C 2 Hs and CH3OH
A solution containing 0.580g (2.02 mmol) of r|®-C5 H 5 Fe(C0 )2 S(0 )2 0 C2 Hs,
1 mL of 1.92 X 10“* M HBFi, in CH3OH, and 50 mL of CH3OH was stirred for
10 hours at 25°C. The CH3OH was removed by rotary evaporation and the residue was dissolved in 15 mL of CHCI3. Chromatography of the solution on a 2.7 X 20 cm Florisil column with CHCI3racetone (v/v) 5II moved a 65 yellow band which yielded 0.463g (84.3%) of Ti®-C5 HsFe(C0 )aS(0 )2 0 CH3
after evaporation of the solvent.
Reaction of ri^-C5 H 5 Fe(C0 )2 S(0 )g0 CH3 and C2H 5 OH
A solution containing 0.546g (2.01 mmol) of ri®-C5 HsFe(C0 )2 S (0 )2 0 CH3 ,
1 mL of 1.9 X 10“^ M HBF* in C2H5OH, and 45 mL of C2H5OH was stirred for
12 hours at 25°C. The solution was evaporated to dryness and the yellow residue was dissolved in 15 mL of CHCI3. Elution of the solution with
CHCI3:acetone (v/v) 5:1 on a 2.7 x 25 cm Florisil column produced an orange band which was collected and evaporated to dryness to yield a yellow powder of ri^-C5 H 5 Fe(C0 )2 S(0 )2 0 C2 Hs, 0.472g (82.6%).
Reaction of ri°-CsHsFe(CO)gS(0)2OCH3 and (+)5 8 9 -2 -0 ctanol
A solution containing 0.252g (1.00 mmol) of ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 ,
4.11g (31.5 mmol) of (+)5 B@-2 -octanol, O.Ollg (approx. 8 x 10“* mol) of
48% aqueous HBF*, and 2 mL of CHCI3 was stirred for 24 hours at 25°C.
The volatiles were removed on the vacuum line at 25°C/0.1 torr. The yellow residue was dissolved in 10 mL of CHCI3 and 20 mL of cyclohexane was added to produce a small amount of an oily material. The solution was decanted from the oil, and the decantate was evaporated to dryness to afford a yellow powder identified as (+)5 8 9 ~0 ^~CsH5 Fe(C0 )2 S(G)2 0 CH-
(CH3)(C6Hi3), 0.321g (83.2%).
Melting Point 118°C (dec.)
NMR (CDCla)! 4.79, singlet, C5 H5 (5) 5.27, broad, CH (1) 8.70-9.14, multiplet, CH2 (10), CH3 (6) 66
IR(KBr) 3105(m), 2950(m), 2925(m), 2870(m), 2855(m), 2070(sh), 2065(s), 2010(s), 1470(m), 1430(m), 1415(m), 1375(m), 1 2 1 2 (s), 1 1 2 0 (m), 1088(s), 1016(m), 966(m), 914(s), 882(sh), 8 6 8 (sh), 850(m), 838(sh), 726(m), 696(m), 634(s), 600(s), 560(s), 555(s), 516(s), 475 (w) cm“^
Specific Rotation (CHCI3 ) [0 ],=;:° = 23.8°
Reaction of (+)sB9-n^-C5H 5 Fe(C0 )2 0 CH(CH3 )(CeHia) and CH3OH
A solution containing 1.98g (5.12 mmol) of
(+)se9-n®-C5 H 5 Fe(C0 )2 S(0 )2 0 CH(CH3 )(C6 Hi3 ), 1 mL of 5.32 x 10”® M HBF^
in CH3OH, and 50 mL of CH3OH was stirred for 48 hours at 25°C. The
CH3OH was removed by rotary evaporation. The octanol was then collected
in a trap in an ice bath (0°C) when the residue was pumped on the vacuum line at 25°C/0.1 torr. The specific rotation of the recovered octanol, 0.193g, was found to be = +8.60 (CHCI3). After the
(+)-2 -octanol had been removed, the resulting yellow solid was extracted with 10 mL of CHCI3 and the extract was filtered to remove a small amount of insoluble material. Rotary evaporation of the filtrate gave 1.16g (83.3%) of n®-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 .
Attempted Reaction of ri°-C5 H 5 Fe(C0 )2 S(0 )2 0 C 2 H 5 and p-Toluenethiol
A solution containing 0.400g (1.40 mmol) of n^-C5 H 5 Fe(C0 )2 S(0 )2 0 C2H 5 ,
0.86g (6.9 mmol) of p-toluenethiol, 1 mL of 1.9 x 10~® M HBF* in CHaCN, and 10 mL of CH3 CN was stirred for 14 hours at 25°C. The CH3 CN was removed by rotary evaporation and the excess of p-toluenethiol was removed by extraction into diethyl ether. A NMR spectrum of the 67
ether insoluble material showed that only unreacted ri®-CsHsFe(C0 )2 S(0 )2 0 C 2 H 5 was present.
2. At Elevated Temperatures
Reaction of n°-C5 HBFe(C0 )2 S(0 )2 0 CgH5 and CHgOH
A solution of 0.465g (1.63 mmol) of n*-C5 H 5 Fe(C0 )2 S(0 )2 0 C 2 H 5 in
40 mL of CH3OH was refluxed for 24 hours. After the solution had cooled, the CH3OH was removed by rotary evaporation. The yellow residue was extracted with CHCI3 and the extract was chromatographed on a 2.7 X 10 cm Florisil column with CHCI3racetone (v/v) 5:1. A yellow band was collected and evaporated to a yellow powder of ri*-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 , 0.233g (51.8%). A large amount of brown decomposition material remained at the top of the column.
Reaction of ri^-CsHsFe (CO) 2 S (0) 2 0 CH3 and C 2H 5 OH
A solution of 0.498g (1.83 mmol) of n^-CsHgFe(CO)2 8 (0 ) 2 0 0 1 1 3 in
55 mL of C 2H 5 OH was refluxed for 24 hours. The solution was then evaporated to dryness to afford a yellow solid which was extracted into CHCI3, and the extract was eluted with CHCl3 :acetone (v/v) 5:1 on a 2.7 X 20 cm Florisil column. A yellow band was collected and evaporated down to a yellow solid. The solid was identified (IR spectrum) as ri®-CsHsFe(CO)2 8 (0 )2 0 0 2 1 1 5 , 0.34g (65%). A large amount of brown decomposition material remained at the top of the column.
Reaction of (+)BB9 -ri°-0 3 H 3 Fe(0 0 )2 S(0 )2 0 0 H(OH3 ) (OeHis) and OH3OH
A solution of l.OBg (2.80 mmol) of
(+)sB9 -r)“-0 5 H 5 Fe(0 0 )2 8 (0 )aOOH(OH3 ) (O6 H 1 3 ) in 60 mL of OH3OH was refluxed for 20 hours. The OH3OH was evaporated to leave a " wet " 68 yellow solid. The octanol was removed from the solid on the vacuum
line at 25°C/0.1 torr and collected in a trap in an ice bath (0°C).
The recovered octanol, 0.186g, was found to have a specific rotation
O of [a]s0 9 = 8.40°. The yellow solid was dissolved in CHCla, the
resulting solution was filtered, and after evaporation of the filtrate,
0.733g (96.2%) of n“-C5 HsFe(CG)2 S(G)2 DCH3 was isolated.
Attempted Reaction of Ti^-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 and C2 H 5 OH at 25°C
After G.4G8g of ri^-CsHsFe(CO)2 8 (0 ) 2 0 0 1 1 3 was stirred in 25 mL of
C2 H 5 OH for 48 hours at 25°C, evaporation of the C2H 5 OH recovered only unreacted n^-CsHsFe(CO)2 8 (0 ) 2 0 0 1 1 3 which was identified by ‘H NMR spectroscopy (CDCI3 ).
Attempted Reaction of ri^-C5 H 5 Fe(C0 )2 8 (0 )2 0 C2 H 5 and CH3OH at 25°C
After 0.433g of ri®-0 5 H 5 Fe(C0 ) 2 8 (0)20C2Hs was stirred in 25 mL of
CH3OH for 48 hours at 25°C, evaporation of the CH3OH recovered only unreacted ri®-CsH5 Fe(C0 )2 8 (0)2OC2 H 5 which was identified by NMR spectroscopy (CDCI3).
Attempted Reaction of ri^-CsHsFe(00)2 8 (0 ) 2 0 0 1 1 3 and (+)5 8 9 -2 -0 ctanol in the Presence of a Radical Initiator at 25°0
A solution containing 0.300g (1.10 mmol) of ri^-CsH5 Fe(0 0 )2 S(0 )2 0 0 H 3 ,
5 mL of (+)s89-2-octanol, 0.020g (8.3 x 10~® mol) of benzoyl peroxide, and 3 mL of OH3ON was stirred at 33°0 for 36 hours under laboratory light. The volatiles were removed on the vacuum line at 25°0/0.1 torr.
The residue was extracted with four 20 ml aliquots of ether. The major portion of the residue remained undissolved and was identified by
NMR spectroscopy (ODOI3) as unreacted ri^-OsHsFe(00)2 8 (0 )2 0 0 1 1 3 . 69
Attempted Reaction of ri^-CjHsFe(0 0 )2 6 (0)2OC2 H3 and Phenol
A solution containing 0.582g of Ti®-CsH5Fe(C0)2S(0)20C2H5, 10 mL
of THF, and 30 mL of phenol vas stirred at 25°C for 16 hours. The THF
was removed by rotary evaporation and most of the excess phenol was
extracted into CCI4 . The insoluble material was dissolved in 20 mL
of CHCla and the extract was charged to a 2.7 x 25 cm Florisil column.
Elution with CHCI3:acetone (v/v) 5:1 produced a single yellow band
which was collected and evaporated to dryness. A ^H NMR spectrum
(CDCI3) of the isolated material showed it to be unreacted
n^-CsH5 Fe(C0 )2 S(0 )2 0 C2 H 5 with a slight phenol impurity.
Attempted Reaction of n^-CsHsFe(CO)2 S (0)2 OC2 HS and CH3 OH in the Presence of KOH
A solution of 0.503g (1.76 mmol) of n^-CsHsFe(CO)2 S (0)2 OC2 H 5 ,
1 mL of 0.107 M KOH in CH3 OH, and 50 mL of CH3OH was stirred for 20 hours at 25°C. After the CH3 OH had been evaporated, a ^H NMR spectrum
(CDCI3 ) of the recovered brown solid showed it to be unreacted n^-C5H5Fe(C0)2S(0)20C2Hs.
Attempted Reaction of n^-C3 H5 Fe(C0 )2 S(0 )2 0 C 2 Hs and NaOCHg
A solution of 0.080g (1.5 mmol) of NaOCHs and 0.286g (1.00 mmol) of ri*-CsHsFe(C0 )2 S(0 )2 0 C2 H5 in 25 mL of CH3OH was stirred for 3 hours, during which time it considerably darkened from the original yellow color. Removal of the CH3OH yielded a brown oil. The oil was extracted with 20 mL of CHCI3 and 20 mL of cyclohexane was added to the extract. When the volume of the solution was reduced to 25 mL by rotary evaporation, a brown precipitate fell out of solution. This 70
precipitate (0.078g) was collected by filtration, and it was not
characterized other than the infrared spectrum below.
IR (Nujol) 2040(s), 1990(s), 1260(w), 1075(s,br) 1050(sh), 1020(sh), 974(s), 850(m), 800(w), 630(sh), 600(w) cm"‘
When the filtrate from above was concentrated to 15 mL, a yellow precipitate formed. After the precipitate was collected by filtration, it was identified as ri“-C5 H 5 Fe(C0 )2 S(0 )2 0 C 2 Hs, 0.125g, by infrared spectroscopy.
Reactions with Amines
Reaction of ri^-C5 HBFe(C0 )2 S(0 )2 0 R and R 2NR'
1 . R = C2H5, R' = H
After 0.300g (1.05 mmol) of r|®-CsHsFe(C0 )2 S(0 )2 0 C2 Hs in 20 mL of
(C2 Hs)2 NH was stirred for 15 to 20 minutes at 25°C, a yellow precipitate fell out of solution. The reaction mixture was stirred for an additional 8 hours and then the (C2 Hs)2 NH was evaporated. The yellow residue was dissolved in 15 mL of CHCI3 , and this solution was treated with cyclohexane until a small amount of a brown precipitate (non-carbonyl) formed. The precipitate was removed by filtration and discarded. The volume of the filtrate was reduced to 10 mL, and addition of 40 mL of cyclohexane produced a yellow precipitate of (C2 Hs)2NH2 [n®-C5 H 5 Fe(C0 )2 S0 3 ],
0.232g (66.7%).
NMR (CDCl3 )x 1.88, broad, NH2 (2) 4.96, sharp, C3 H 5 (5) 7.04, broad, -CH2 - (4) 8.62, broad, -CH3 (6 ) 71
IR (KBr) 3070(m), 2990(m), 2925(m), 2885(m), 2730(m), 2510(m), 2410(w), 2175(m), 2030(s), 1990(s), 1960(sh), 1630(w), 1432(m), 1428(m), 1210(w), 1170 (sh), lllO(s), 1080(s), 1055(sh), 1045(s), 962(vs), 872(vw), 850(w), 844(w), 830 (w), 800(w), 640(s), 612(s), 598(m), 578(s), 568(s), 502(s), 485(s) cm"'
2. R = CaHs, R' = H
Two reaction flasks, A and B, were each charged with 0.320g
(1.11 mmol) of r)®-CsH5 Fe(C0 )2 S(0 )2 0 C2 Hs. Flask B also contained 0.015g
(9.5 X 10“® mol) of benzoyl peroxide. Each flask was treated with
20 mL of (C2 Hs)2NH at 25°C. The solutions in each flask slowly
darkened, and after complete dissolution of the n®-C5HsFe(C0 )aS(0 )aOCaHs,
a yellow precipitate formed in each flask within 5 minutes. The
(CaHs)2NH2 [ri®-CsH5 Fe(0 0 )2 8 0 3 ] in each flask formed in oa. 80% yield,
approx. 0.260g. It was identified by IR and 'H NMR spectroscopy.
3. R = CH3, R' = H
Within 2 minutes of the addition of 20 mL of (CH3 )aNH to 0.300g
(1.10 mmol) of ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 at 0°C the resulting solution
darkened and a yellow precipitate formed. The reaction mixture was
stirred for an additional 1.5 hours, and the excess (CH3 )aNH was then removed under a stream of Na. The yellow-brown solid was dissolved
in 10 mL of CHCI3, and filtration of this solution removed a small amount of black material which was discarded. Addition of 30 mL of cyclohexane to the filtrate and concentration of the resulting solution to 30 mL afforded a yellow, air-stable solid of
(CH3)2NH2[n'-CsHsFe(C0)aS03], 0.284g (85.1%). 72
NMR (CDCl3 )T 0.92, broad, -NHa (2) 5.00, singlet, C 5H 5 (5) 7.43, broad, CH3 (6 )
IR (KBr) 3070(m), 2995(m), 2950(m), 2730(m), 2490(m), 2040(vs), 1980(vs), 1434(m), 1430(m), 1260(w), 1110(vs), 1060 (s), 990(w), 960(vs), 848(m), 828(w), 628(s), 609(s), 572(s), 554(s), 506(s), 490(w), 480(w), cm“^
Attempted Reaction of ri°-CaH3Fe(C0)aS(0)20C2H5 and (C2Hs)3N
A solution containing 0.429g of r)°-CsH5Fe(C0)2S(0)20C2H5 in 20 mL of (C2Hs)3N was stirred at 25°C for 72 hours and then refluxed for 2 more hours. After the (C2Hg)3N was removed under reduced pressure, the resulting yellow residue was identified as unreacted ri^-C5H 5Fe(C0 )2 S(0 )2 0 C 2H 5 by infrared spectroscopy.
Preparation of ri^-C5HBFe(C0)2S(0)2N(CH3)2
A solution of Na[n^-CsHsFe(CO)2 ] was prepared by reduction of
2.66g (7.51 mmol) of [r)*-CsHsFe(C0)2]2 with excess 1% sodium amalgam in 200 mL of THF. The solution was treated dropwise with 1.6 mL
(15 mmol) of C1S(0)2N(CH3)2 in 20 mL of THF. After addition of
5 mL of this solution, the reaction mixture turned from a faint yellow to a red color. After the rest of the C1S(0)2N(CH3)2 was added, the solution was stirred for 14 hours at 25°C. The volatiles were removed on the vacuum line at 25°C/1 torr. The purple-red residue was extracted with 250 mL of CHCI3 and the extract was filtered to remove any insolubles. The filtrate was concentrated to 40 mL, and this solution was added to a 2.7 x 20 cm Florisil column. Elution with
CHCI3 produced a long purple band of [ri°“C5H5Fe(C0)2 ]2 , 1.65g (62.0%). 73
A second, bright red band followed and, after collection and concen
tration of this fraction, 0.152g (5.00%) of r^-CsH5Fe(C0 )2Cl was
obtained. When the solvent was switched to CHCla;acetone (v/v) 3:1, a
small yellow band passed down the column. This band was collected
and, after rotary evaporation of the solvent, 0.075g (1.8%) of a
yellow, air-stable powder of Ti®-CsH5Fe(C0 )aS(0 )2N(CH3 )2 was isolated.
"H NMR (CDCla)T 4.82, singlet, C5H 5 (5) 7,28, singlet, NCH3 (6 )
IR (Nujol) 3095(m), 2045(vs), 2002(sh), 1985(vs), 1220(vs), 1095(w), 1075(sh), 1064(vs), 1025(w), 1008(sh), 933(m), 900(w), 870(m), 855(sh), 835(vw), 655(s), 612(s), 570(vw), 555(s), 498(m), 460(m) cm“^
Reactions with Electrophiles
Preparation of [n^-C5H 5Fe(C0 )2 (8 0 (0 0 2 8 5 )2 )]PFe
A solution of 0.723g (2.53 mmol) of ri^-CsH5Fe(C0 )2 S(0 )2 0 C 2H 5 and
0.613g (2.47 mmol) of (C2H5)30PF6 in 35 mL of CHCI3 was stirred for 6 hours at 25°C. During this time the solution slowly darkened from yellow to brown. After the volatiles were evaporated, the resulting yellow-brown solid was extracted with 25 mL of CH2CI2 , and the extract was filtered to remove a small amount of a brown, insoluble material.
Addition of 25 mL of cyclohexane to the filtrate immediately induced formation of yellow-brown crystals. The volume of the solution was reduced to 30 mL, and the yellow, air-stable crystals were collected by filtration and identified as Iri*-CsH5Fe(C0 ) 2 (S0 (0 C 2Hs)2 )]PF6 ,
0.641g (59.5%). 74
Analytical Data Calc, for CiiHisFeOsSPFgl 28.69% C, 3.29% H Found: 29.09% C, 3.31% H
NMR ((CD3 ):C0 )T 4.08, singlet, C5H 5 (5) 5.25-5.75, multiplet, -CH2- (4) 8.56, triplet (J = 7Hz), -CHg (6 )
IR (hexachlorobutadiene) 3130(m), 2960(sh), 2925(m), 2860(m), 2085(vs), 2050(vs), 1420(m)
IR (Nujol) 1264(m), 1224(vs), 1095(w), 990(s), 920(s), 880(s), 842-22(vs), 775(m), 738(m), 582(m), 551(s), 540(sh) cm"^
A^(CH3N02) 86.5 ohm-1 ^,^2 ^0 1 ^ - 1
Preparation of [n’^-C5HsFe(C0 ) 2 (S0 (0 CH3 ) (OC2H5 ) ) ]PFe
As a solution containing 0.528g (2.13 mmol) of
n“-C5H 5Fe(C0 )2 S(0 )2 0 CH3 and 0.526g (2.12 mmol) of (C2Hs)3 0 PF6 in 30 mL of CH2CI2 was stirred for 6 hours at 25°C, it slowly darkened from yellow to brown. After the volatiles were evaporated, the resulting light brown residue was extracted with 25 mL of CH2 CI2 . The extract was filtered to remove a small quantity of insoluble material. Addition of 25 mL of cyclohexane to the filtrate immediately produced light brown crystals. The solution was concentrated to 30 mL, and yellow, air-stable crystals of [n^-C5H 5Fe(C0 )2 (S0 (0 C 2H 5 )(OCH3 ))]PFe, 0.554g
(58.6%), were collected by filtration.
"H NMR ((CD3 ):C0 )T 4.15, singlet, C 3H 3 (5) 5.2-5.7, multiplet,-CH2"(2) 5.97, singlet, OCHs (3) 8.57, triplet, CH2 CH3 (3)
IR (Nujol) 3095(m), 2085(s), 2050(s), 1260(w), 1224(vs), 1152(w), 1102(w), 988(m), 920(vs), 880(vs), 840-20(vs), 770(m), 602(sh), 588(vs) cm”*
A (CH3NO2 ) 89.6 ohm~^ cm® mole~^ m 75
Reaction of [n°-C3H 8Fe(C0 )a(S0 (0 CaH5 )2 )]PF6 and C2H 3OH
A solution of 0.330g (0.652 mmol) of [n’-C5HsFe(C0 )a(S0 (0 C 2Hs)2 )]PF6
in 20 mL of CaHsOH was stirred for 16 hours at 25“C. The volatiles were removed under reduced pressure and the resultant yellow residue was taken into the glove box. An IR spectrum of this residue showed
that ri^“CsH5Fe(C0 )aS(0 )a0 CaH5 and PFg were present.
IR (Nujol) 2060(s), 2005(s), 1212(s), 1095(s), 1060(s), 970(s), 885(sh), 840-20(s) cm-i
When the Nujol mull was exposed to air for 5 minutes the spectrum recorded was that of n^-CsHsFe(CO)2 8 (0)2011 and PFe“ .
IR (Nujol) 2062(s), 2018(s), 1184(s), 1038(b ), 840-820(vs)
The rest of the material was removed from the glove box and extracted
into 40 ml of acetone. The extract was filtered to remove a small amount of insoluble material, and the filtrate was concentrated to 5 mL.
After 40 mL of (€2115)20 was added to the concentrated solution, filtration of the mixture afforded ri°~C5H 5Fe(C0 )2 S(0 )2 0 H, 0.157g (93.3%).
Reaction of ri°-C5H 5Fe(C0 )2 S(0 )2 0 C 2H 5 and HCl
Gaseous HCl was slowly bubbled through a solution of 0.301g
(1.05 mmol) of ri®-C5H 5Fe(C0 )2 8 (0 )2OC2H 5 in 30 mL of THF for 10 minutes and the solution was stirred an additional 2 hours at 25°C. It was then concentrated to a red oil by rotary evaporation. The red oil was dissolved in 10 mL of CHCI3, the resulting solution was filtered, and 10 mL of cyclohexane was added to the filtrate. Slow rotary evaporation of this solution afforded red crystals which were 76
identified by infrared and NMR spectroscopy (6 6 ) as
n=-C,HsFe(C0)2Cl, 0.183g (86.1%).
NMR (CDCl3 )T 4.80, singlet, C5H 5
IR (Nujol) 2055(s), 2009 (s)
Reaction of n^-CsHsFe (CO) 2 8 (0 )2 0 ^ 3 and CF3CO2H
In an NMR tube 0.8 mL (10 mmol) of CF3CO2H was added to 0.5g
(2 mmol) of ri*-C5HsFe(C0 )2 S (0 )2 0 CH3 . As the reaction progressed, the
solution changed color from yellow to red, and the peaks at T 6.46 (CH3)
and T 4.85 (C5H5) were observed to decrease in intensity. After 7.5
hours the following peaks were recorded: T 6.46, 6.18, 5.13, and 4.90,
but the T 6.46 peak, corresponding to unreacted r)*-C5HsFe(C0 )2 S(0 )2 0 CH3 ,
was barely detectable. The peak at t 4.90 matches well the chemical
shift of C5H5 in O^-CsHsFe(CO)2O2CCF3, T 4.92 (83). Integration of
the peaks at T 6.18 and T 5.13 gave an intensity ratio of 3:1,
respectively.
Attempted Reaction of ri^-CsHBFe(CO) 2 8 (0)2002115 and HF
Anhydrous gaseous HF slowly passed through a solution of 0.550g of r)®-CsH5 Fe(C0 )2 S(O)2 0 C 2Hs in 40 mL of CHCls for 20 minutes at 25°C.
After the solution had been stirred for 30 minutes at 25°C, the volatiles were removed under reduced pressure, 25°C/0.1 torr. The reaction flask was taken into the dry box and the recovered material was identified by infrared spectroscopy as unreacted rf-CsHsFe(CO)2S(0)2OC2H5. 77
Reaction of ri°-C8H 5Fe(C0 )2 S(0 )2 0 CH3 and HBFz,
In an NMR tube in the glove box 0.200g (0.742 mmol) of r)®-CsH5Fe(C0 )2 S(0 )2 0 CH3 in 2.5 mL of CDCI3 was treated with 0.1 mL
(approx. 0.7 mmol) of HBF/,» (€2115)2 0 . As the reaction progressed, the
C5H5 resonance at t 4.55 for n^-CsHsFe(CO)2 8 (0)200113 slowly decreased in height whereas two new peaks of equal intensity at T 4.67 and T 4.73 slowly increased in height. The CHs resonance of n'-CsHsFe(CO)2 S (0)2OCH3 was under the methylene quartet from (C2Hs) 2 0 at T = 6.18. After 75 minutes, the peak at x 4.55, corresponding to unreacted
O^-CsHsFe(CO)2 8 (0)200113 was barely detectable, but the C5H5 peaks at
T 4.67 and x 4.73 of equal intensity were sharp and strong, and new peaks of relative intensity 1:3 at x 6.35 and x 6.90 were observed.
The ^®F NMR spectrum of the reaction mixture remained unchanged through out the course of the reaction.
^®F NMR (CeFe) 6.74ppm, broad singlet, BF*
Reactions of the Bisulfito and Sulfito Complexes
Acidity of n°-C5HsFe(C0 )2 8 (0 )2 0 H
The pH of a solution containing 0.0331g of ri®-C3H 5Fe(C0 )2 8 (0 )2 0 H in 25 mL of H 2O was determined to be 2.38. Titration of 10 mL of this solution to a pH = 7 required 5.14 x 10 * mole of NaOH (1.030 mL of
0.4992 M solution). These titration data give an equivalent weight of 260g/mole whereas the calculated molecular weight from the formula is 258g/mole. The titration data are graphically presented in Figure 4. 1 0
pH
G
4
3
ml X 1Q-2 NaOH
Figure 4. Titration Curve for the Neutralization of a 10 mL Aliquot of a Solution of 0.0331g of n’-CsHsFeCCOaSCOzOH in 25 mL of HzO with 0.04992 M NaOH. 00 79
Reaction of r)°-C3H 3Fe(C0 )aS(0 )a0 H with NaOH
To a solution of 0 .396g (1.43 mmol) of n®-C5H5Fe(CO)aS(0)aOH in
10 mL of HaO, 14 mL of 0.101 M NaOH (1.42 mmol) was added dropwise with stirring at 25°C. The HaO was removed at 25°C/1 torr on the
vacuum line. To remove any unreacted ri’-CsHsFe(C0 )aS(0 )a0H, the
residue was extracted with 10 mL of GHaCN. The suspension was
filtered, and 0 .390g (97 .4%) of yellow, air-stable Na[ri^-C5H5Fe(C0)aS03] was collected on the filter funnel.
NMR (DaO/(CDa)aCO)T 4.95, singlet, C5H 5
IR (KBr) 3150(w), 3130(m), 3095(m), 2065(sh), 2050(vs), 1994(vs), 1439(m), 1434(m), 1426(m), 1129(s), 1107(s), 1084(s), 1072 (s), 1035(sh), 1024(w), 1019(w), 984(s), 974(sh), 907(w), 889(vw), 880(w), 834(s), 837(m), 629(s), 610(s), 595(sh), 577(s), 573(s), 558(s), 514(m), 502(w), 498(sh) cm""
A (CH3OH) 69.7 ohm ^ cm* mole ^ m
Reaction of r]°-C5H5 Fe(C0 )aS(0 )a0 H and (CaH5 )aNH
In 10 mL of CH3CN 0.084g (0.33 mmol) of n^-CsH5Fe(C0 )2 S(0 )a0 H and 0.030g (0.41 mmol) of (CaH5 )2NH were stirred for 5 hours at 25°C.
After the volatiles were removed by rotary evaporation, the resulting yellow-brown residue was dissolved in 20 mL of CHCI3. The solution was filtered to remove a small amount of insoluble material, and evaporation of the filtrate to dryness afforded a yellow powder of
(CaH,)aNHa[n*-C,H3Fe(C0)aS03], O.lOlg (92.5%). 80
Reaction of ri°-C5H 5Fe(CD)2 S(0 )2 0 H and CH3OH
After a solution of 0.213g (0.827 mmol) of n^-C5H5Fe(C0 )2 S(0 )g0 H
in 30 mL of CH3 OH had been stirred for 24 hours at 25°C, the excess
CH3OH was removed by rotary evaporation. The resulting yellow solid
was dissolved in CHCI3 and the solution was filtered to remove a small
amount of a brown residue. When the filtrate was evaporated to dryness,
0.134g (59.6%) of ri®-C5H 5Fe(C0 )2 S(0 )2 0 CH3 , identified by infrared
spectroscopy, was isolated.
Reaction of n^-C5H5 Fe(C0 )2 S(0 )2 0 H and C2H5OH
In the same fashion as the reaction described immediately above,
0.200g (0.775 mmol) of ri®-C5 HsFe(C0 )2S (0 )2ÛH in excess C2H 5OH (30 mL)
was converted to r)^-CsH5Fe(C0 )2 S(0 )2 0 C2Hs, 0.210g (94.7%).
Reaction of n^-C5 H 5Fe(C0 )2 S(0 )2 0 H and (+)sa9-2 -0 ctanol
A solution containing 0.651g (2.52 mmol) of ri®-C5HsFe(C0 ) 28 (0 )2 0 H,
0.040g (approx. 4 x 10 ® moles) of 48% aqueous HBFi,, and 4.11g (31.6 mmol)
of (+)5 3 9-2 -octanol in 25 mL of CH3CN was stirred for 48 hours at
25°C. The volatiles were removed from the reaction mixture at 25°/0.1
torr on the vacuum line. The resulting yellow residue was dissolved
in CHCI3 and the solution was added to a 2.7 x 10 cm Florisil column.
Elution with CHCI3:acetone (v/v) 5:1 developed a yellow band which was
collected and evaporated to dryness to yield a yellow powder of
(+)5 B*-n'-C5H,Fe(C0 )2 S(0 )2 0 CH(CH3 )(C6Hi3 ), 0.787g (80.9%). This complex was treated with 1 mL of 1.92 x 10"* MHBFi, in CH3OH and 50 mL of CHgOH.
After the CH3OH was removed by rotary evaporation, (+)-2-octanol, O ([a]##9 = + 8 .2 0 ), 0.123g, was then recovered from the reaction residue. 81
Reaction of n°-C3HsFe(C0 )2 S(0 )2 0 H and SOCI2
A solution containing 0.15g (0.59 mmol) of ri^-CsH5 Fe(C0 )2 S(0 )2 0 H,
0.66g (0.66 mmol) of SOCI2 , and a drop of dimethylformamide in 10 mL
of CHCI3 was stirred for 4 hours at 25°C. The color of the solution
slowly changed from yellow to red. The volatiles were removed on the
vacuum line at 25°C/0.1 torr to leave a red oil. An infrared spectrum
of this oil showed it to contain n®-C5HsFe(C0 )2Cl and not materials with sulfur-oxygen bonds.
Reaction of n^-C5H 5Fe(C0 )2 S(Q)2 0 H and ClCOCOCl
Although n^-C5H 5Fe(C0 )2 S(0 )2 0 H (O.lBOg) initially appeared to be , insoluble in 25 mL of benzene containing 0.087g of ClCOCOCl, the solution slowly darkened from yellow to orange over 7 hours, as the ri^-CsHsFe(CO)2 8 (0)2011 was consumed. The volatiles were removed by rotary evaporation to produce a red oil. An infrared spectrum of the oil showed it to be only r^-C5HsFe(C0 )2Cl. No species with sulfur- oxygen bonds were detected.
Exchange Reaction of R 2NH2 [n^-C5 H 5Fe(C0 )2 S0 3 ] and NaB(CgHs)6
1. R = CH3
A slurry of 0.333g (1.11 mmol) of (CHs)2NH2 [r)^-C5H 3Fe(C0 )2 S0 3 ] and 0.435g (1.15 mmol) of NaB(C6H5 )i, in 70 mL of CHCI3 was stirred for
24 hours at 25°C. The yellow solid was collected by filtration and washed with 100 mL of CHCI3 and 100 mL of acetone. It was identified by infrared spectroscopy as Na[ri®-C5HsFe(C0 )2 S0 3 ], 0.239g (74.3%). 82
2. R — C2H5
A solution containing 0.190g (0.574 nmol) of
(C2Hs)2NH2 [n*-C,H5Fe(C0 )2 S0 3 ] and 0.206g (0.602 nmol) of NaB(C6Hs)<.
in 60 mL of CHCI3 and 0.5 mL of acetone was stirred for 16 hours at
25°C. The solution was filtered, and the collected yellow precipitate
was washed with two 15 mL aliquots of CH3CN. This yellow precipitate
was identified by infrared spectroscopy as Na[ri®-CsH5Fe(C0 )2 S0 3 ],
0.132g (82.1%).
Attempted Reaction of Na[ri°-C5HsFe(C0 )2 S0 3 ] and CH3 I
A solution of 0.123g of Na[ri®-C5H5Fe(C0 )2 S0 3 ], 10 mL of CHgl,
10 mL of C2H5OH, and 10 mL of acetone was heated at reflux for 10 hours.
Over this period of time, the solution had slightly darkened in color.
The volatiles were removed from the solution by rotary evaporation
leaving a yellow-brown material. The material was extracted with 20
mL of acetone, and filtration of the extract collected O.lOlg (82.1%)
of unreacted Na[ri®-C5H 5 Fe(C0 )2 S03 ].
E. Miscellaneous Reactions
Preparation of n°-CBH5Fe(C0 )2 (O3 SC6HA-P-CH3 )
As O 2 was bubbled through a solution containing 1.50g (4.25 mmol)
of [ri’-C5H 5Fe(C0 )2 ] 2 and 1.62g (8.50 mmol) of P-CH3C 6H 5 S (0)2OH in 75 mL
of acetone and 10 mL of H 2O, the color slowly changed from purple to
bright red over a one hour period. The volatiles were then removed
on the vacuum line at 25°C/0.1 torr. Extraction of the resulting oil with 25 mL of CHCI3, followed by filtration of the extract, removed 83
some insoluble material. The filtrate was concentrated to 5 mL, and
addition of 75 mL of cyclohexane with vigorous stirring caused a red
powder to form. Collection of the red powder by filtration afforded
1.43g (46.0%) of n’-CsHsFeCCOzCOaSCsH^-p-CHa) (84).
Melting Point 93°C
Analytical Data Calc, for CitHizFeOgS: 48.30% C, 3.47% H, 9.21% S Found; 48.14% C, 3.77% H, 9.37% S
NMR (CDCla)T 2.33-3.07, multiplet, -CgHt- (4) 4.90, singlet, C5H 5 (5) 7.68, singlet, -CHa (3)
IR (KBr) 3150(w), 3125(w), 3000(w), 2940(w), 2056(s), 2018 (s), 1705(m), 1440(m), 1298(sh), 1271(s), 1181(m), 1155(s), 1132(m), 1104(s), 1067(m), 1034(m), 1020(m), 1011(m), 1004(m), 978(s), 875(w), 863(w), 837(m), 825(s), 816(m), 715(m), 680(s), 590(m), 580(s), 566(s), 548(s), 519(s) cm“ ^
Mass Spectrum (100°C) /e = 354 for [n=-C=H5 Fe(C0 )2 ] 2 (76) /e = 326 for (n®-C5H 5 )aFez (C O a . (38) /e = 298 for (n'-C5H 5 )aFe2 (C0)z (72) /e = 186 for (n=-CsH5 )2Fe+ (1 0 0 ) /e = 177 for n®-CsH5 Fe(C0 )j+ (62) /e = 171 for p-CHaC6H^S0 3 + (35)
Preparation of [n°-C5H 5Fe(C0 )(L)(S0 (0 C2Hs)(CHa))]PFs
1. L = CO
In 30 mL of CH2 CI2 0.428g (1.67 mmol) of n^-C5HsFe(C0 )2 S (0)2CH3 and 0.416g (1.68 mmol) of (C2Hs)a0 PF6 were allowed to react at 25°C for 1 2 hours, during which time the solution slowly darkened from yellow to light brown. The mixture was then evaporated to dryness by rotary evaporation and the resulting yellow solid was extracted with
30 mL of CH2 CI2 . Filtration of the extract removed some insoluble 84
material, and addition of 30 mL of cyclohexane to the filtrate followed
by concentration of the solution to 45 mL, afforded 0.537 (74.8%) of
[r)®~CsHsFe(C0 ) 2 (SOCOCzHs) (CHa) ) ]PFc which was collected by filtration.
Analytical Data Calc, for CioHigFeOaSPF*: 27.93% C, 3.05% H Found; 27.86% C, 3.00% H
"H NMR (CDaClz)! 4.39, broad, C 5H 5 (5) 5.66, singlet, S-CIla (3) 6.40, broad, OCHaCHa (2) 8.56, broad, -CHa-CHa (3)
’’H NMR ((CDa)aCO)T 4.33, very broad 5.66, very broad 6.36, very broad 8.56, broad
IR (KBr) 3110(m), 3010(w), 2920(w), 2077(vs), 2040(vs), 1473(w), 1425(m), 1390(m), 1323(m), 1190(vs), 994(sh), 980(vs), 880(vs), 842(sh), 828(vs), 765(m), 718(m), 596(m), 569(sh), 558(s), 536(s), 495(m), 455(m) cm~^
(CHaNOa) 85 ohm ^ cm' mole ^
2 . L = PPha
In 25 mL of CHaCla 0.580g (1.18 mmol) of n®-CsH5Fe(C0 )(PPha)S(0 )aCHa and 0.295g (1.12 mmol) of (C2Ha)aOPF6 were allowed to react at 25°C
for 48 hours. After the volatiles were evaporated off, the orange residue was dissolved in 20 mL of CHaCla and the solution was filtered to remove a small amount of insoluble material. Addition of 30 mL of cyclohexane to the filtrate and concentration of the resulting solution to 35 mL precipitated 0.52g (70%) of [n®-C5HaFe(C0)(PPha)(SO(OCaHa)(CH3))iPFg which was collected by filtration. 85
Analytical Data Calc, for CayHaBFeFsOaPzS: 48.81% C, 4.25% H Found: 48,98% C, 4.45% H
"H NMR ((CD,)2 C0 )T 2.38, multiplet, CeHs (15) 4.76, singlet, C5H 5 (5) 6.00, broad, -CHa- (2) 6.55, broad, -S-CH3 (3) 8.92, broad, -CH2CH3 (3)
IR (KBr) 3122(w), 3062(w), 2990(w), 2940(w), 1990(vs), 1945 (w), 1585(vw), 1570(vw), 1480(m), 1435(s), 1423(m), 1410(m), 1368(sh), 1318(m), 1265(w), 1188(s), 1170(sh), 1125(sh), llOO(s), 1080(sh), 1038(w), 1020(w), 1008(m), 968(s), 8 8 8 (vs), 865(sh), 850(vs), 842(vs), 768(sh), 760(s), 706(s), 560(s), 548(s), 542(sh), 525(s), 511(m), 503(m), 435(m) cm"'
(CH3NO2 ) 80 ohm~^ cm® mole~^ RESULTS AND DISCUSSION
I. Organo-Transitlon Metal-Dithlonite Complexes
A. Synthesis and Characterization
Prior to this work it had been established that reaction of a
slight excess of SO2 with Nafn'-CsHsFefCO):] results in the formation
of [n^-CsHsFeCCOzlaSOa and [n^-CsHsFe(CO) ] 2 (CO) (SO2 ) (18-21). When a
large excess of S0 2 is employed in the reaction (Eq. 14, p. 10), a
third product was recovered from the reaction mixture after chromato
graphy on Florisil. Based on the elemental analysis and spectroscopic
data, the third reaction product had been tenatively identified as
ri’-CsH5Fe(C0 )2-S(0 )2-S(0 )2-Fe(C0 )2ri*-CsH5 , and a later molecular weight
determination by this author (2 1 ) supported the formulation.
In the solid state [r)“-CsHsFe(C0 )2 S02 ]2 exhibits good stability,
but it slowly decomposes to [ri*-CsH5 Fe(C0 ) ] 2 (CO) (SO2 ) on storage in
solution. This decomposition precluded the formation of crystals
suitable for an x-ray crystallographic study of this novel complex in which the two iron atoms are bridged by a dithionite linkage.
The NMR spectrum of [ri®-CsH5Fe(C0 ) 2 SO2 ]2 exhibits a resonance at T 4.64 which does not broaden down to -40°C in (CD3 )2C0 solution (21)
This is indicative that both CgHs rings are in the same magnetic environment. The infrared spectrum, listed in Table 2 and partially
86 TABLE 2
INFRARED SPECTRA OF THE TRANSITION METAL DITHIONITES,
DIPHENYL-a-DISULFONE, AND SODIUM DITHIONITE
1 Compound vCO cm vS0 2 cm“ ^ b
a [^^"CsHsFe(CO)2 SO2]2 2070(m), 2059(m-s) , 2044(s) 1223(s). 1040(s)
[Mn(C0 )sS0 2 ] 2 2146(m), 2090(sh). 2060(s). 2040 (s) 1224(s), 1195(w). 1070(w).
1037(s)
[Re(C0 )sS0 2 ] 2 2150(m), 2090(sh). 2060(s). 2035 (s) ^ 1 2 1 2 (s), 1190(w). 1069(w),
1031(s)
[CsHsS0 2 ] 2 d 1325 (s). 1300(w). 1150(s) ^
Nâ2 8 2 0 zi 1070(w), 998(vw)
CHCI3 solution. ^ Nujol mull. CH2CI2 solution. Ref. 85.
00 o o
F e - S - S - F ë
O
(A) (B)
2000 1300 1200 1100 1000 9 0 0 FREQUENCY (CM”')
Figure 5. Infrared spectrum (Nujol) of [ri’-CsH5 Fe(C0 )2 S0 2 ] 2 in A) the 2100 to 1900 cm“ ^ region and B) the 1300 to 900 cm“^ region.
CO 00 89 reproduced in Figure 5, contains only terminal carbonyl bands at 2070(m),
2059(m-s), and 2044(s) cm” ^ (CHCI3 solution). Significantly, the infrared spectrum contains only two bands at 1223(s) and 1040(s) cm~^
(Nujol) from anti-symmetric and symmetric SO2 stretching, respectively.
The absence of more S-0 vibrations (up to four may be present) indicates a very symmetrical linkage. A similar complex which contains the -S2OÜ- linkage (34), diphenyl-a-disulfone CeHg-S(0 )2 -S(0 )a-CeHs also exhibits only two v(S0 2 ) bands at 1325 and 1150 cm"^ (85).
The reaction of [ri®-C5HsFe(C0 ) 2 ]S0 2 with SO2 lends strong support to the dithionite structural assignment, since the structure of
[ri^-C5H 5Fe(C0 )2 ]2 S0 2 has been determined (18,19).
o o
L ÎJe# * S O 2 ^ h o t T H F 6 6 6
0 0 0 0 (35)
A summary of reasonable pathways leading to the formation of the various iron-sulfur dioxide products is depicted below, but, owing to the complexity of the reaction system parts of it are speculative
(25). 90
SO [rf-CsHsFefCO):]' % [n’-CsHsFeCCOaSOz]'
fO]
SO n®-CsHsFe(C0 )2 S0 -SO
dimerize dimerize
/ [n®-C5HsFe(C0)2]2 [n'-C=H5Fe(C0)2S02]
[n=-C5HsFe(C0)2]2S0:
—CO
[n*-C5H5Fe(C0)];(C0)(S02) (36)
The first step of the reaction is well-founded, since reaction of
K[n*-C5H 5Fe(C0 )2 ] with SO2 formed the isolable 1 : 1 adduct,
K[ri®-C5H 5Fe(C0 )2 SO2 ] (24). The identity of the oxidizing agent is suspected to be SO2, a known oxidant (8 6 ), because air was excluded from the solutions. At high SO2 concentrations, the
[r)^-C5 HsFe(C0 )2 S0 2 «] species should also be present at high concentration, and coupling of two of these radicals would then account for the forma tion of [n“-CsH5Fe(C0 )2 S0 2 ]2 .
When the V(CO) and v(SÛ2 ) absorptions of [ri’-CsHsFe (C0 ) 2 ] 2 8 0 2 and
[ri'-CsHsFe(0 0 )2 8 0 2 ] 2 are compared as shown in Table 3, the peaks for
[ri*-CsH5 Fe(C0 )2 S0 2 ] 2 are substantially shifted to higher energy. This shift can be attributed to an increase in positive charge on the iron in the Ti®-CsHsFe(C0 ) 2 moiety on going from [n*-C5HsFe(C0 )2 ] 2 8 0 2 to TABLE 3
COMPARISON OF v(CO) AND v(S0 2 ) ABSORPTIONS FOR [r)^-C5HsFe(C0 )2 ]2 S0 2 and [n=-C,H,Fe(C0 )2S02]2
Compound v(C0) cm~^^ v(SOa) cm-i^
[n'-C3HsFe(C0 )2 S0 2 ] 2 2070(s). 2059(m-s), 2044(s) 1223(s), 1040(s)
[n’-CsHsFe(C0 )2 ]2S0 2 2027(vs), 2015(vs), 1965(s), 1953(vs) 1135(s), 993(s)
^CHCls solution. ^Nujol mull. 92
[ri’-C3HsFe(C0 )2 S0 2 ]a. This results in a reduction of Fe-to-S ir
bonding, and, thus, the vCSOa) bands are at higher energy. The more
positive iron in [r|®-CsHsFe(0 0 )2 8 0 2 ] 2 also causes a reduction in the
shift of electrons from the metal to CO TT'* orbitals, and, as a result,
the V(CO) of the terminal carbonyls are found at higher energy.
An alternative explanation may be proposed for the relative
positions of V(CO) and vCSOa) for [ri*-C5H 5 Fe(C0 )2 ]2 S02 and
[ri’-CsHsFeCCO) 2 SO2 ]2 . Both irons in [rj^-CsHsFe(CO) 2 ]2 SO2 are TT bonding
to the same sulfur, but each iron in [ri*-CsHsFe(C0 )2 S0 2 ] 2 is tt bonding
to a different sulfur. This results in a larger build-up of electron density at sulfur in [r^-C5H 5Fe(C0 )2 ]2 S0 2 , and, as a consequence, the
8 - 0 bond order is lowered and the V(S0 2 ) stretching frequencies are at lower energy than those in [ri®-CsH5Fe(C0 ) 2 SO2 ] 2 . Since both irons in
[r)^-CsH5Fe(C0 )2 ]2 SO2 are TT bonding to the same sulfur, the amount of
Fe-to-S TT bonding is limited, and more electron density must be shifted from the metal to the tt'^ orbitals of CO. This lowers the C-0 bond order, and the v(CO) of the terminal carbonyls are at lower energy.
When other metal carbonyl anions, [ti^-C5H 5M(C0 )3 ] (M = Mo, W), were allowed to react with SO2 , stable 1:1 adducts did not result, but, rather, oxidation occurred to form the metal dimers and other neutral species.
Na[n=-CsHsMo(C0 )3 ] + SO2 (excess) [n'-CsHsMo(CO)3]2 Hg
+ [n“-CsHsMo(C0 )3 ]2Hg (37) 93
Na[n®-CsH5W(C0 )3 ] + SO2 (excess) [n’-CsHsWCCOsJa
+ (n=-C5H5 )2W 2 S2 02 + Material " A " (38)
The oxidations were immediate; when the metal anion solutions were
exposed to SO2 , they instantly changed color from yellow to purple-red,
the color indicative of the dimers [ri®-CsH5M(C0 )3]2 (M = No, W). Since
air was excluded from these reaction mixtures, the oxidizing agent [0 ]
is suspected to be SO2 (8 6 ).
Mercury from the sodium amalgam which was used in the preparation
of Na[r)^-CsH5Mo (CO) 3 ] from [ri^-CsHsMo (CO) 3 ] 2 must enter into the
reaction to form the mercury derivative, [c^-CsHsMo(CO)s]2Hg, in
Equation 37. In fact, several cases have been reported where mercury
containing species are produced as by-products in the conversion of metal carbonyl dimers to metal carbonyl anions with 1% Na/Hg amalgam
(87,88).
Material " A " and (ri®-C5Hs)2W 2 S202 which will be discussed in more detail on page 1 0 2 were formed besides [r^-C5HsW(C0 )3]2 in
Equation 38. The infrared spectrum of material " A " contains V(CO) bands at 2030(s), 1950(s), and 1895(s) cm“ ^ and v(S0 ) 2 bands at 1141 and 1063 cm“ ^ (Nujol). The position of the V(S0 2 ) bands precludes a dithionite linkage (by comparison with the positions of V(S0 2 ) in
[ri’-CsH5 Fe(C0 )2 S0 2 ]2 ) even though the elemental analysis showed a
W to S ratio of one to one. Based on Kubas's criteria (5), the position of the v(S0 2 ) bands best fits a structure where SO2 bridges two metals. However, the structure of material ” A" remains unassigned, because two elemental analyses showed a large variation in tungsten 94
content, 37.88 Vs. 50.21%, and repeated attempts at recrystallization of this solid from acetone by addition of ether led only to decomposi tion.
In a similar fashion to tin(II) chloride (65),
[n®-C5H5Fe(C0)2]2Hg + SnCl2 -+ [n'’-C5HsFe(C0)2 ]aSnCl2 + Hg (39)
SO2 is capable of displacement of Hg in [ri^-C5 H 5Fe(C0 ) 2 ] aHg to form the iron dithionite complex:
[n^-C5H,Fe(C0 )2 ]2Hg + SO2 (excess) [ri=-CsHsFe(C0 )2 S0 2 ] 2 + Hg
(40)
After work-up by column chromatography on Florisil, [ri®-C5HsFe(C0 )2 S0 2 ]2 is isolated in slightly higher yield than from reaction of
Na[r|®-C5H 5Fe(C0 )2 ] and SO2 , 23 vs. 16%. Other complexes such as
[ri®-C5H 5W(C0 )3 ]2Hg, [tl^-C5HsMo(C0 )3 ]2Hg, [Co(C0 ) ^ 2Hg, and
[Co(CO)3 (P-n-Bus)]2Hg in which tin(II) halides displace Hg (65) failed to react with SO2 . That [ri^-CsHsMo(CO)3 ]2Hg did not react was expected, since the *'H NMR spectrum of it was recorded in SO2 , and the authors gave no indication that any reaction had taken place (77). In
[Co(CO)3 (P-n-Bu3 )]2Hg displacement of Hg by SnCl2 was very facile (65), but SO2 failed to displace Hg in this complex even when the reaction was carried out in a bomb at 25°C for 72 hours.
The final step in the formation of [ri^-CsHsFe(0 0 )2 8 0 2 ] 2 from
Na[ri*-CsH5Fe(C0 )2 ] and SO2 was proposed to be the coupling of two
[r|“-CsH5Fe(C0 )2 S0 2 »] radicals (Equation 36). The [ri®-CsH5Fe(C0 )2 S0 2 *] species may be viewed as the product of reaction of [r^-C5H 5Fe(C0 )2 *] 95
and SOg. The [n'-CsH5Fe(C0 )2 *] radical as well as other metal carbonyl
radicals can be photochemically generated (87-89). As shown in
Table 4, the ultraviolet-visible spectra of the metal carbonyl dimers
display peaks which have been assigned to the o ^ a* transition of the
metal to metal bonds (89-91). Photolysis at or near the wavelength
corresponding to the energy of this a ->• a* transition results in
promotion of an electron from the O to orbital. As a result of this
promotion, the bond is destabilized to such a degree that it homolyti-
cally cleaves to afford two metal carbonyl radicals.
A new route to a series of metal dithionite complexes was
developed when metal carbonyl radicals were generated in the presence
of SO2 :
[M]2 + SO2 (excess) ^ [M-j-S (0)2 -S(0)2-fM] (41)
M Solvent Yield
n®-C5H5Fe(C0)2 THF 23%
Mn(CO), THF 11%
Re(CO) 5 CfiHe 3.5%
Although [n^-C5HsFe(C0 )2 S0 2 ] 2 formed in a relatively short period of time, extended photolysis periods were required to produce low yields of [Mn(C0 )5 S0 2 ] 2 and [Re(C0 )5 S0 2 ]2 . The iron dithionite complex was separated from the other materials such as [ri®-CsHsFe(C0 )2 ] 2 and
[r|®-CsH5Fe(CG)2 ]2 S02 in the reaction mixture by column chromatography on Florisil. Both [M(C0 )5 SÜ2]2 (M = Mn, Re) complexes were easily isolated; owing to the low solubities of these species, they TABLE 4
ULTRAVIOLET-VISIBLE SPECTRA OF SELECTED METAL CARBONYL DIMERS
0 0 Complex a a*, A(c) ir^ -> a*, A(e)
[n'-CsHsFeCCOzla ® 3450(8,700) 4150(1,600)
[n’-CsHsMoCCOala ^ 3890(31,000) 5150(1,860)
[n=-C5H,W(C0 )3 ] 2 ^ 3620(20,200) 4930(2,450)
Mn 2 (CO)io ^ 3420(21,400) 3900(sh)
R6 2 (CO) 10 3080(17,000)
^ Cyclohexane solution. ^ CCI4 solution. Ref. 90. ^ Isooctane solution. Ref. 91.
VO 97
precipitated out of solution as they formed. The extremely low solubitity
of [Re(C0 )sS0 a]2 prevented further purification, but [Mn(C0 )5 S0 a]2
could be recrystallized from CHgOH:THF (v/v) 1:1 by slow addition of
cyclohexane.
The dithionite complexes, [M(C0)sS02]2 (M = Mn, Re), were identified
by elemental analyses and infrared spectroscopy, and a molecular weight
determination for [Mn(C0)sS02]2 corroborates the formulation. The
V(CO) and vCSOa) bands for each complex are listed in Table 2. As
shown in Figure 6, each complex, as expected by analogy with
[ri®~CsH5Fe(C0)2S02]2 j exhibits only two SO2 peaks: at 1224 and 1037
cm“ ^ for [Mn(CO) 5SO2 ] 2 and at 1212 and 1031 cm~’’ for [Re(CO)5 SO2 ] 2 •
The solution infrared spectra of (C0 )5M-S(0 )2~S(0 )2-M(C0 )s (M = Mn, Re)
also augment the structural assignment. If an octahedral configuration
at M is assumed for a [(C0 )sMS0 2 ] moiety, then 4 carbonyl stretching
frequencies (2Ai + E + Bi modes) are predicted from Ci,v local
symmetry at M (92,93). Since the Bx mode is infrared inactive, only
three bands are expected in the CO region. However, in complexes of
the type M(CO)sX (M = Mn, Re) where the M-X group lacks axial symmetry,
often the intense E mode splits and the Bi mode appears with low
intensity (93). For both [M(C0 )sS0 2 ] 2 (M = Mn, Re) complexes, four bands are observed in CH2CI2 , and based on their intensity and position (93) they can be assigned with confidence: the peaks at
2146 (Mn) or 2150 (Re) cm“ ^ correspond to the Ai mode for the equatorial carbonyls, the weak peaks at 2090 cm” ^ (Mn and Re) correspond to the
Bi mode, the intense peaks at 2060 cm~^ (Mn and Re) correspond to the
E mode, and the peaks at 2040 (Mn) or 2035 (Re) cm~^ correspond to the 98
Figure 6 . Infrared spectra (Nujol) of A) [Mn(CO)sS0 2 ]2 and
B) [Re(CO)5 SO2 ]2 in the 1300 to 900 cm“ ^ region. 99
9 9 (CO) cM n -S-S-M n(CO) ' O II II O O
(B)
9 o (CO)^Re-S -S-Re(CO)p,
^ 6 6
1 3 0 0 1200 1100 1000 9 0 0 FREQUENCY (CM’*)
Figure 6 100
Al mode for the axial CO. The solution infrared spectra of
[MnCCOsSOala, Mn(CO)sBr, and Mn(CO)sS (OaCHaCeHs in the 2200 to 1900
cmT* region are displayed for comparison in Figure 7. The spectra are
similar in appearance with respect to the intensity and relative
positions of the carbonyl stretching frequencies, but the band for the
E mode of Mn(C0 )sS(0 )2 CH2 C 6 H 5 is split. The E mode in [M(C0 )sS0 2 ] 2
(M = Mn, Re) is not split apparently because the axial group in a
[M(C0 )sS0 2 ] fragment does not have a large perturbing effect. Since
only four terminal carbonyl bands are observed in the infrared spectrum
for complexes which contain a total of 1 0 terminal carbonyls, it
appears that both [M(C0 )sS0 2 ] moieties of [M(C0 )5 S0 2 ] 2 (M = Mn, Re)
are equivalent. O The 3500 A lamps employed in this study were not monochromatic
(spectral distribution from approximately 3100 A to 4250 A), and they were capable of supplying the broad range of energy which was necessary to effect the a a* transition for the different metal carbonyl dimers examined. The first step in the photochemical synthesis of the dithionites is thought to be homolytic cleavage of the metal to metal bond of the dimers to produce the metal carbonyl radicals
[M»]. In turn, the [M«] radicals react with SO2 to form [MSO2 '], and coupling of two of these species produces the dithionite complexes.
The relatively high SO2 concentrations reduce the probability of coupling of [M«] and [MS0 2 «] to produce [M#S(0 )2 fM] by lowering the concentration of [M*]; if any [M^S(0)2 fM] does form it may react with
SO2 to form [M^S(0 )2 -S(0 )2 -[M] which is a known reaction for M = ri®-C5H 5 Fe(C0 ) 2 (Equation 35). (A) (B) (C)
2200 2000 1900 2200 2000 1900 2200 2000 1900 FREQUENCY (CM"')
Figure 7. Infrared spectra of A) [Mn(CO)5 SO2 ] 2 in CH2 CI2 ,
B) Mn(CO)sBr in CHCI3 , and C) Mn(CO)5 S (0)2 CH2 C 6H 5 o in CHCI3 in the 2200-1900 cm~^ region. H* 102
[M], 2[M.] (42)
[M«] + SO 2 [MSOz»] (43)
2[MS02«] ^ [M^S(0)2-S(0)2-tM] (44)
M = n®-C5H5Fe(C0)a, Mn(C0)5, Re(CO)s
The reaction sequence above (Equations 42-44) is similar to the one proposed for the formation of dibenzyl-a-disulfone from the
reaction of benzyl radicals and SO2 (85):
2 C6 H 5 CH2 ' + 2 SO2 2 C6 H 5 CH2 SO2 ' (45)
2 C6H 5 CH2 SO2 ' -4- C6H5CH2-S(0)2-S(0)2-CH2C6Hs (46)
Entirely different results were observed when SOa-saturated O solutions of [ri^~C5H5M(C0)3]2 (M = Mo, W) were exposed to 3500 A irradiation I
_ 3 5 0 0 A ,S. JD C5H5)M(C0)3]2 . SO2 ^ o" “ 2 M =Mo, W (47)
Both (ri®-C5Hs)2Mo2S202 and (r|*-CsH5)2W2S202 were separated from starting materials by column chromatography of the reaction mixture on Florisil. Extensive decomposition was evidenced by the large amounts of brown, non-carbonyl materials which remained at the top of the chromatography column. Also, a small amount of material ” A"
(vide supra) was isolated when [ri“-CsHsW(C0 )3 ] 2 was photolyzed. 103
The identification of (ri’-C5 Hs)2Mo 2 S2 0 2 and (r)“-CsHs)2W 2 S2 C 2 was
facilitated by the fact that Dahl (94) had reported the crystal structure and infrared data for (ri’-CsHs ) 2M0 2 S2 O 2 . The two products were identified by elemental analyses, molecular ion peaks in the mass spectra C^/e = 418 for (n^-C5H 5 )2 **Mo2 S2 0 2 ^ and ™/e = 594 for
(n^-C5 Hs)2 ^^^#2 8 2 0 2 ), and terminal (M=0) bands at 927 cm“^ for
M = Mo (94) and at 910 cm~^ for M = W in the infrared spectra. The spectroscopic data suggest that (n°-C5 Hs)2 W 2 S2 0 2 is very similar in structure to (n“-CsHs)2Mo2 S2 0 2 (94).
Photolysis of solutionsof [ri®-C5 HsM(C0 )3 ] 2 (N = Mo, W) with
3500 A lamps should cause homolysis of the M to M bonds. The resulting
[n^~C5 H 5M(C0 )3 *] radicals have been reported to be labile and lose CO dissociatively to yield 15 electron intermediates which dimerize to give complexes with metal to metal triple bonds (95).
CL CpO h v M. M. o ^ ' h o o
. A CO -CO V
M= <=
M = Mo,W (48)
The dimers rather than the [ri®-CsH5M(C0 )3 »] (M=Mo,W) radicals appear to be the species which react with SO2 . Thermally synthesized 104
[n“-CsHsMo(CO)2 ]2 (69) reacts with SO2 to afford
(ri*—CjHs ) 2M 0 2 S2O 2 «
[n=-C,H,Mo(C0)3]2 T^ntie (CO)2]2 + 2C0 (49)
[n^-C5 H5 Mo(C0 )2 ] 2 + SO2 (excess) ^ (n^-CsHs)2Mo2 S2 0 2 (50)
The triple bonds in [r|^-C5 H5M(C0 )2 ] 2 (M = Mo, W) are reactive towards
aliénés (96), acetylenes (97), and carbon monoxide (69) and, on this
basis, one can propose the following sequence for the reaction with
SO2 :
= M S O 2 => s o /' c
M = Mo , W
V
m ===m ‘’'’ C 0 2 O' 'S'
(51)
The presence of CO2 as a reaction product was detected in the photolysis of [ti®-C5 H 5 W(C0 ) 3] 2 and SO2 in a closed system. A peak at ™/e = 44 for C0 2 ^ was observed in the mass spectrum, and the infrared spectrum of a gas sample collected from the closed system exhibited a band at
2350 cm” ^. Nakamoto (80) lists the following absorptions for CO2 :
Vi = 1343 cm"* (IR inactive), V 2 = 667 cm”* (IR active), and V 3 = 105
2349 cm” ’' (IR active). The band due to the V 2 mode was obscured by
peaks from THF which was used as the solvent.
Attempts at the preparation of [ri^-CsH5 Fe(C0 )2 S0 2 ] 2 by a metatheti-
cal reaction between ri“-C5 HsFe(C0 )2 Cl and M 2 S2O 4 (M = Na, Tl) or by a
ligand substitution reaction between [ri^-CsHsFeCCO) 2 (H2 O) ]BF/, and
Na2 S2 Ûi, were unsuccessful. However, small quantities of
[n^-CsHsFeCCOlaCCOXSOa) (M = Na, Tl) and [n^-CsHsFeCCO)2 8 0 2 ] 2
(M = Tl) were among the many products which were isolated by column chromatography on alumina from the metathetical reaction mixtures.
Both products may result from reaction of the sulfur dioxide radical anion, SO2 * , and ri®-CsH5 Fe(C0 )2 Cl. Solutions of Na2 S2 0 z, are known to have detectable concentrations of S0 2 *~ which is formed through homolytic dissociation of the S-S bond (33).
B. Reactions of Metal-Dithionite Complexes
Thermolysis and Photolysis Studies
The initial step in either photolysis (98) or thermolysis (99) of diphenyl-a-disulfone is believed to involve homolytic scission of the
S-S bond of the -S2 O4 - linkage.
C6H5-S(0)2-S(0)2-C6Hs 2C6H,S02' (52)
In another species which contains S2 O 4 , Na 2 S2 0 i,, the S-S bond of the
S2 0 i,*~ ion spontaneously dissociates in solution. These reports suggested that the -S2 O4 - linkages in [M#S(0 )2 -S(0 )2 fM] (M = ri’-C5 HsFe(C0 )2 , Mn(CO)s> Re (CO) 5) may exhibit similar behavior.
Based on the composition of the reaction products, photolysis and 106
thermolysis studies conducted on these complexes indicate that the S-S
bond is homolytically cleaved, The proposed scheme for the mechanism
of photochemical or thermal decomposition of the dithionites shows
that the first step involves homolysis of the S-S bond;
[M4S(0)2-S(0)2-tM] ^ ^ 2[MS02*] (53)
[MSOa*] 4- [M«] + SO a (54)
2[M«] 4- [M]a (55)
[M.] + [MSOa'] [M4 S(0 )a{M] (56)
[MjS(0 )afM] ^ [MSOa'] + [M'] (5 7 )
M = n=-C5 H 5 Fe(C0 )a, Mn(CO)s, Re(CO),
In turn, the species [MSOa'] may undergo loss of SOa by analogy with the reported lability of metal carbonyl radicals (91). Coupling of two [M'] species generates the dimers [M]a which are the principal reaction products of the studies described below.
In the ionizing beam of the mass spectrometer (70-80°C) the three metal dithionites [M#S(0)j-S(0)atM] (M = n^-CsHsFe(CO)a, Mn(CO)5 ,
Re (CO)5 ) dissociated to form the metal dimers [M]a and SOa. Equations
(53-57) accord with these results.
When a solution of [ri^-CsH5 Fe(C0 )aS0 a]2 in THF was maintained at reflux for 3 hours, [ri“-C3 H 5 Fe(C0 )a] 2 and [n“-CsHsFe(CO) ]a (CO) (SOa) were separated by column chromatography in yields of 77 and 15%, respectively, from the reaction mixture. Since [n’-CsHsFe(CO)]a(CO)(SOa) is known to result from thermal decomposition of [n^-C5 H 5 Fe(C0 )a]2 S0 a 107
(18), coupling of [n“-CsHsFe(CG)2 «] and [r)®-CsH5 Fe(CQ)2 SG2 *] (Equation
56) likely accounts for the formation of [ri®-CsH5 Fe(C0 )2 ]2 S0 2 .
When [Mn(C0 )5 S0 2 ]a was heated in a sublimation apparatus at
97°C/1 torr, it decomposed without evolution of SO2 . The decomposition
material contained terminal carbonyls in the infrared spectrum, and
broad, ill-defined peaks from 1175 to 91G cm~^ indicated that some
type of a sulfite or sulfate complex had formed (IGG). Support for
a sulfite or sulfate product is provided by the insufficient volatility
of the material to obtain a mass spectrum. The S-S bond of the -S2 O4 -
linkage apparently did not homolytically dissociate, since SO2 was
not evolved and Mn2 (CG)io did not sublime onto the cold finger of the
sublimation apparatus.
The photolysis of THF solutions of [MS0 2 ] 2 (M = îl^-CsHgFe(CO)2 , O Mn(CO)s) with 35GG A lamps under CO purge led to extrusion of SO2 from
the complexes. In 15 minutes [n^-CsHsFe(0 0 )2 8 0 2 ] 2 was converted to
[r)'*-C5 H 5 Fe(C0 )2 ] 2 and [r^-C5 H 5 Fe(C0 )2 ]2 S0 2 . If the photolysis time was extended to one hour, extensive decomposition resulted such that no identifiable products were isolated. When [Mn(0 0 )5 5 0 2 ] 2 was photolyzed for IG minutes, it was partially converted to Mn 2 (0 0 )io, but photolysis for 3G minutes led to formation of Mn2 (0 0 )io as the only isolable product. Again, based on the composition of the products, irradiation of the metal dithionite complexes results in homolytic cleavage of the S-S bond of the -S2 0 4 -linkage as depicted in Equations
53-57. The ultraviolet-visible spectra (Table 5) of
[ri®-0 5 H 5 Fe(C0 )2 S0 2 ] 2 and [Mn(0 0 )5 S0 2 ] 2 contain broad absorptions within the spectral distribution (31GG A to 425G A) of the 350G A lamps. 108
and irradiation may supply sufficient energy to the dithionite complexes
to induce homolysis of the S-S bond. The [n®-C5 HsFe(CG)2 ]2 S0 2 complex which is also formed in the irradiation of [ri®-C5 H 5 Fe(C0 )2 S0 2 ] 2 contains
ultraviolet-visible absorptions within the spectral range of the 3500 Â
lamps, and it smoothly extrudes SO2 to afford tn®-C5 H 5 Fe(C0 )2 ] 2 in high yields (18).
TABLE 5
ULTRAVIOLET-VISIBLE SPECTRA OF [n®-C5HsFe(C0)2802]2, [n'-CsHsFe(CO)2 ]2 8 O 2 ,
AND [Mn(C0)s802]2 from 2700 A TO 6000 Â
Compound Bands A(e) ^
[O^-CsHsFe(0 0 )2 8 0 2 ] 2 3180(sh), 4380(7,100)
[n®-C5HsFe(C0)2]2802 3320(5400), 3620(sh)
[Mn(C0 )sS0 2 ] 2 3830(1670)
^ CH2 CI2 solution.
It is interesting to note that the [ri^-CsHsFe(0 0 )2 8 0 2 ] 2 and
[Mn(C0 )sS0 2 ]2 complexes extrude SO2 at or near the same energy that is employed for their photochemical preparation from [ri®-C5 H 5 Fe(C0 )2 ] 2 and Mn 2 (CO)io and SO2 . This may account for the low conversions of
[r| —CgHsFe(CO)2 ] 2 or Mn 2 (CO)j,o and SO2 to [f] —C5 H 5 Fe(C0 )2 S0 2 ] 2 or
[Mn(C0 )5 S0 2 ] 2 (Equation 41). 109
Reactions of Metal Dithionites and Electrophiles
Cleavage of [n*-CsH5 Fe(CG)aS0 2 ] 2 with RI (R = CH3, C2H5, CHfCHaja)
in THF solution at reflux yields Ti®-C5H 5 Fe(C0 )2 S(0 )2 R and
nf-CsHsFeCCO);!.
[()|^-C5H5)Fe(C0)2S02]2 + RI 0%^-C 5 H ^ F e ( C 0 )2 6 (0 )2 R
R = CHg, C 2 i -C 0f-C5H^)Fe(CO)2l
(58)
No evidence was obtained for the formation of the species
ri®-CsH5 Fe(C0 )2 S(0 )2 S(0 )2 R. When alkyl bromides, RBr (R = C2 H 5 ,
CH(CH3 )2 ), were used, only [n^-C5 H 5 Fe(C0 )2 ]z and
[ri^-CsHsFeCCO) ] 2 (CO) (SO2 ) were isolated. These products result from
thermolysis of [ri^-CsH5 Fe(C0 )2 S0 2 ] 2 in THF rather than reaction with
the alkyl bromides. The difference in the reactivity of RI vs. RBr may be attributable to the fact that C-I bonds are weaker and therefore more reactive than C-Br bonds (101).
Methyl iodide and [Mn(CO)5 SO2 ]2 failed to react at 80°C for 3 hours, and the manganese dithionite was recovered in greater than 80% yield. This result indicates that the -S2 O 4 - linkage is more stable in [Mn(C0 )sS0 2 ] 2 than [n'’-C5 HsFe(C0 )2 SO2 ]2 , since [n^-C5 HsFe(C0 )2 S0 2 ] 2 reacts with CH3 I, and, at 80°C, it also thermally extrudes SO2 .
When [Ti“-CsH5 Fe(C0 )2 S0 2 ] 2 in CH2 CI2 at 25°C was allowed to react with the hard electrophile C^Hs^ (from (C2Hs)3 0 PF6 ), numerous products were formed. After the solvent was removed from the reaction mixture, a ^H NMR spectrum (CDCI3 ) of the resulting residue indicated that four 110
types of ri'-CsHsFe materials were present (T = 4.42, 4.66, 4.71, and
4.77 for CsHs protons). When the reaction mixture was worked up by
column chromatography, only a single yellow band which contained
n®-C5 HsFe(C0 )aS(G)2 0 CH2 CH3 (82) was collected. One of C5 H 5 resonances
in the NMR spectrum before work-up must be due to
ri®-C5 HsFe(C0 )2 S(0 )2 0 CaH5 , but the other n’-CsHsFe containing materials were not identified. If any o^-CsHsFe(CO)2 8 (0 ) 2 0 2 1 1 5 had been generated,
it would have been isolated by column chromatography (81). A red material at the top of the column remained immobile even with polar
solvents, and this suggests that the material is ionic in nature.
Possible species such as [r|°-C5 H 5 Fe(C0 ) 2 (8 0 (0 0 2 1 1 5 )2 ) ]PFe or
[r|®-0 5 H 5 Fe(0 0 ) 2 (8 0 (0 0 2 1 1 5 ) (O2H5) ]PFe which would result from electro-
philic attack on n^-OsHsFe(0 0 )2 8 (0 )2 OO2 H 5 or n®-0 5 H 5 Fe(0 0 )2 8 (0 )2 O 2 H 5
by 0 2 H 5 ^ (to be described later in this work) can be eliminated from
consideration, since the O5H5 resonances for these complexes are found
oa. 4.10 T. There were no resonances in the NMR spectrum of the
reaction residue which correspond to this position.
The electrophile, 02115"*", may initially attack one of the oxygens of the dithionite linkage, and because of the complexity of the reaction
(4 types of n®-0 5 H5 Fe), any suggested mechanism after the alkylation would be purely speculative. Ill
0 0 r\ C Op II II 2 5 C Tl®—CsHsFe(CO)2 —S-S—Fe(CO)aH —C5H5 + (CaH5)30PF6 «-i II II LiHaOJ-a 0 0
0 0 n^-CsHsFe(COa)-S-W -Fe(CO)an=-CsH. PFe -»■ n®-C5H5Fe(C0)aS(0)a0CaH5 II I:
+ Unidentified Materials (59)
Reaction of [rf-C5H5Fe(C0)aS0a]a with Reducing Agents
Jablonski's (24) report on the stable isolation of
K[ri®-C5H5Fe(C0)aSOa] prompted studies on the susceptibility of the S-S bond in [ri®-C5H5Fe(C0)2S02 ]a to reduction to form [ri^-C5H5Fe(C0)aS02 ] .
However, the S-S bond was inert to cleavage by KH to form
K[ri*-CsHsFe(C0)aS02] and Ha in THF at 25°C. If the reduction of
[Tl^-CsH5 Fe(C0 )aSOa]2 was attempted with Na/Ka.e, a reaction did take place, but K[ri®-CsH5 Fe(C0 )aS0 a] (24) was not detected (infrared spectrum) as a reaction product. A ^H NMR spectrum exhibited resonances for three different r^-CsHgFe containing materials (l = 4.77, 4.95, and 5.18), but these materials were not identified. The infrared spectrum of the reaction mixture did eliminate [ri^-C5 H 5 Fe(C0 )a]2 S0 a and [ri*-CsH5 Fe(C0 ) ] a (CO) (SOa) as possible candidates for the reaction products. SUMMARY
A route to a photochemical preparation of a series of transition
metal dithionite complexes [M]-S(0 )g-S(0 )2 -[M] from [M]g
(M = r)®-C5 HsFe(C0 )2 , Mn(CO)s, Re (CO) 5 ) and SO2 was successfully
developed. The iron dithionite complex [ri^-CsHsFe(CO)2 SO2 ]a also
results from reaction of Na[ri®-C5 H 5 Fe(C0 ) 2 ] with SO2 , reaction of
[n^-C5 HsFe(C0 )2 ]2Hg with SOg , and reaction of [ri^-C5 HsFe(C0 ) 2 ]gSOg with SO2 . Studies were conducted on the dithionite complexes in order
to compare the chemistry demonstrated for their -S2 O 4 - linkages with
the known chemistry of the -S2O 4 - linkage in diary1 -a-disulfones.
Under photochemical or thermal conditions the S-S bond in
[M#S(0 )2 -S(0 )gfM] is apparently cleaved in the first step of reaction which eventually leads to extrusion of SOg and formation of the metal carbonyl dimers [M]g (M = n^-C5 HsFe(C0 )2 , Mn(CO)5 , and Re(CO)s). The
-S2 0 /,-linkage in [r^-C5 H 5 Fe(C0 )gS0 2 ] 2 is subject to attack and cleavage by electrophiles; reaction with alkyl iodides, RI, affords rf-C5 H 5 Fe(C0 )gS(0 )2 R, and reaction with (CgH5 )3 0 PF6 affords
T| —CsHsFe(CO)2 S (0)gOC2H 5 • Whereas [r] —C5H 5 Fe(C0 )gS0 2 ] 2 is stable towards KH, a powerful reducing agent, it reacts with Na/Kg.*, but the
-S2 O4 - linkage in it is not reduced to K[n'-C5H 5 Fe(C0 )2 S0 g], a known, isolable species (24).
112 113
II. Organo-Transltlon Metal-Alkylsulflto Complexes
A. Synthesis and Characterization
The alkylsulfito complexes Ti°-CsHsFe(CO)28(0)aOR were prepared by a variety of methods. The most direct and facile method involved a ligand substitution reactions
[n®-C5H 5 Fe(C0 )2 (H2 0 )]BF^ + Na[S(0 )2 0 R] (60) 25°
R = CH3, CaHs n^-C5H5Fe(C0)aS(0)20R + NaBF» + H2O
Since only the methyl and ethyl salts Na[S(0 )2 0 R] are sufficiently stable to isolation (74), the aforementioned procedure was slightly modified for the synthesis of the 1 -propyl and 2 -propylsulfito complexes :
[n®-C5H 5Fe(C0 )2 (H20)]BFi, + Na[S(0)2OC2H 5] + R'OH (excess)
n®-CsH5 Fe(C0 )2 S(0 )2 0 R' + NaBF* + C2 H 5OH (61)
R' = I-C3 H 7 , 2 -C3 H,
These reactions undoubtedly proceed via a rapid equilibrium
25° Na[S(0 )2 0 CaH5 ] + R ’OH (excess) ^ Na[S(0 )2 0 R'] + C2 H 5 OH (62)
R ’ = I-C3H7, 2 -C3 H?
as evidenced by the interconversion of Na[S(0 )2 0 CH3 ] and Na[S(0 )2 0 C2 Hs] through dissolution and storage in excess ethyl and methyl alcohol, respectively. When the modified synthesis was attempted with phenol, only r|®-C5 HsFe(C0 )2 S(0 )2 0 C2 Hs was isolated, which indicates that 114
Na[S(0 )aOC2 Hs] and phenol will not equilibrate to form Na[S(0 )2 0 C 6 Hs].
The ethylsulfito complex was also prepared by another modification of the ligand substitution reaction:
[n®-C5HsFe(C0)2(H20)]BF^. + Na2S0a (excess) + C2H5OH (excess)
n’-CsH5 Fe(C0 )2 S(0 )2 0 C2 H 5 + NaBF^ + H 2 O (63)
The n®-CsH5 Fe(C0 )2 S(0 )2 0 R (R = CH3 , C 2 H 5 , I-C3 H 7 , and 2 -C3 H 7 ) complexes, prepared in the reactions described above, were isolated in yields of 40-50% after removal of the reaction solvent, extraction of the residue into CHCI3 , and chromatography of the extract on
Florisil. The complexes are yellow, air-stable solids.
In the mass spectra of r)^-CsH5Fe(C0)2S(0)20CH3 and r|®-C5 H 5 Fe(C0 )2 S(0 )2 0 C 2 Hs the parent ion, P^, is either absent or weak; + 4. however, peaks corresponding to (P-CO) and (P-2C0) are readily discernible. The 1-propyl and 2-propyl complexes decomposed to
[ri“-C5H5Fe(C0)2]2 atid SO2 in the mass spectrometer. There were no detectable peaks at ™/e = 90 for 1-propanol or 2-propanol or at
™/e = 89 for the 1-propyl or 2-propyl radical.
For alkylsulfito complexes metal to sulfur bonding was established in [Ni(S(0)2 OC2 HS)(tris(2-diphenylphosphinoethyl)amine)]BP\*0.SC^HsOH'O.SHzO
(40). Since the infrared spectra of the n*“CsH5Fe(C0)2S(G)20R complexes show two terminal V(S=0) bands which correspond to the antisymmetric and symmetric stretching modes of SO2 , Fe to S bond must occur; 0 II Fe-S-OR. If the alkylsulfito ligands were attached to the Fe through 0 115 0 an oxygen, Fe-O-S-OR, only one terminal V(S=0) band would be observed.
Besides two terminal carbonyl bands, the n^-C5 H 5 Fe(C0 )aS(0 )2 0 R complexes display characteristic infrared absorptions (Table 6 ) for
V(SOa), V(C-O), and V(S-O). The positions of the antisymmetric and symmetric SOa stretches appear in the narrow ranges of 1214-1211 cm~^ and 1095-1084 cm ^, respectively, and the C-0 and S-0 stretches appear within the limits of 996-918 cm"^ and 640-634 cm~^, respectively.
The positions of these bands compare favorably with those reported for other alkylsulfito complexes; the two SOa bands for
(PPh3 )aPd(S(0 )aOCH3 )a are found at 1237 and 1091 cm"*, and the C-0 stretch is found at 952 cm” * (42). The infrared spectrum of r)®-C5 HsFe(C0 )aS(0 )a0 CH3 , reproduced in part in Figure 8 , shows two terminal carbonyl peaks at 2064 and 2007 cm"*, two SOa peaks at 1214 and 1095 cm"*, and the C-0 stretch at 971 cm” *. TABLE 6
IMPORTANT STRETCHING FREQUENCIES IN n^-CsHsFeCCO) zS(0)zOR AND OTHER METAL-ALKYLSULFITO COMPLEXES
Complex V(C0) V(SOz) V(C-O) V(S-O) cm-i
n’-CsHsFeCCO)zS(0)zOR*
R = CHs 2064, 2007 1214, 1095 971 636
R = CHzCHa 2062, 2000 1214, 1088 971 1061
R = CH2CH2CH3 2068, 2014 1211, 1087 973
R = CH(CH3)z 2070, 2014 1211, 1112, 918 640 1084, 1065
R = CHCCHa)(CgHia) 2062, 2018 1212, 1088 996 634
(Pha?)zPd(S(0)zOCHa)z*'^ 1237, 1091 948
(PhaP)zPt(S(0)zOCHa)z*'^ 1243, 1099 952
KBr. All absorptions strong.
Ref. 42.
'Ref. 42 and 43. O' (A) (B)
0
9 9 Fe-S-O-CH-3 c1 o II o
-i I L J L 2000 1300 1200 noo 1000 900 800 FREQUENCY (CM"‘)
Figure 8 . Infrared spectrum (KBr) of n^-C5 HsFe(C0 )2 S(0 )2 0 CH3 in the 2100-1900 cm”^ and 1300-800 cm~^ regions. 118
The V(CO) and V(SOa) bands of n®-CsH5 Fe(C0 )2 S(0 )2 CH3 (81) and ri^-CsHsFe(0 0 )2 8 (0 ) 2 0 0 1 1 3 are presented for comparison in Table 7.
TABLE 7
OOMPARISON OF v(00) and v(SOa) ABSORPTIONS FOR
n®-OsH5Fe(00)2S(0)20H3 AND n^-CsHsFe(00)2 S (0)aOOH3
Compound v(CO) V(S0 2 ) cm~^ n=-CsH5Fe(C0)2S(0)2CH3 2058,2009 * 1194,1052 b
n®-C5 H 5 Fe(C0 )2 S(0 )2 0 CH3 2064,2007 c 1214,1095 ^
^ OH2 OI2 solution. ^ Nujol mull. ^ KBr. All absorptions are strong.
Although the carbonyl absorptions for both complexes are of similar energy, the SO2 absorptions of ri^-C5 H 5 Fe(C0 )2 S(0 )2 0 R are shifted to higher energy. Since the methylsulfinate ligand (-8 (0 )2 0 8 ^) was postulated to be a tt electron acceptor (81), the shift of the SO2 absorptions of the methylsulfito ligand to higher energies indicates that it is a weaker it electron acceptor from the iron. In the methyl sulf ito ligand, OCH3 can also tt bond to sulfur, and thus the sulfur receives less electron density from the terminal oxygens.
The *'H NMR spectra of the ri*-C5 HsFe(C0 )2 8 (0)2 OR complexes, presented in Table 8 , display no unusual features and are entirely consistent with the assigned structures. The spectrum of 119 TABLE 8
NMR SPECTRA FOR (ri®-CsH5)Fe(C0) 28(0) aOR
Complex Chemical Shift(t)^ Intensity Assignment
R = CHa 4.79 s 5 CsHs 6.41 s 3 CHa
R = CH2CH3 4.60 s 5 C5H5 5.99 q (J = 7 Hz) 2 CHa 8.77 t (J = 7 Hz) 3 CHa
R = CHaCHaCHa 4.68 s 5 C5 H 5 6.14 t (J = 6 Hz) 2 CHaCHaCHa 8.14 m (J = 6 Hz, 2 CHaCHaCHa = 6 Hz) 9.08 t (J/ = 6 Hz) 3 CHaCHaCHa
R = CH(CHa)2 4.83 s V 5 CsHs 5.10 sp (J = 6.1Hz) 1 CH 8.25 d (J = 6.1Hz) 6 CHa
R = CH(CH3)(C6Hi3) 4.79 s 5 C5 H 5 5.27 br 1 CH 8.70 - 9.14 m 16 5-CHa-, 2CHa
R = H -1.16 s'^ 1 OH 4.70 s 5 C5 H 5
^CDCla solution except as noted. Abbreviations: s, singlet; d, doublet; t, triplet; q, quartet; sp, septuplet; m, multiplet or complex pattern; br, broad.
^Two component peaks of presumed septuplet appear to overlap the C5H5 resonance. c. ■(0 0 3 ) 2 8 0 solution. 120
n'-C5 H 5 Fe(C0 )2 S(0 )a0 CH(CH3 )2 , presented in Figure 9, consists of
three resonances: a doublet at T 8.25 (J = 7 Hz), a septuplet at
T 5.10 (J = 7 Hz), and a singlet at T 4.83, assigned to the CH3, CH,
and C5H5 protons, respectively. The strong C5H5 resonance appears to
overlap two component peaks of the presumed septuplet for the methine
proton resonance.
After the series of ri^-C3 HsFe(C0 )2 S(0 )2 0 R complexes had been
successfully prepared by the ligand substitution reaction (Equations
60, 61), efforts were directed toward developing other synthetic
routes to alkylsulfito complexes. Jablonski (24) reported that
K[Ti^-C5 H 5 Fe(CO)2 S0 2 ] reacted with CHs0 S(0 )2 F to afford 0 II 0 -CsH5 Fe(C0 )2 -S-OCH3 . It was felt that oxidation of the methoxy-
sulfenate ligand in n^-C5 HsFe(C0 )2 S(0 )0 CH3 would be another means of preparing r^-C5HsFe(C0 )2 S(0 )2 0 CH3 . When Jablonski's (24) work was repeated, it was determined that the product had been incorrectly identified as rf-C5 H 5 Fe(C0 )2 S(0 )0 CH3 . The actual product of the reaction is n^-C5 H 5 Fe(GG)2 S(0 )2 0 CH3 , and this was confirmed by ^H NMR and infrared spectroscopy. 121
TMS
10 r
Figure 9. NMR spectrum of r|®-CsHsFe(C0)2S(0)20CH(CH3); in CDCla with TMS as internal standard. 122
8 K 9 A , 8 o T ® p 0 -A - O -C K] C H ÿ l g c 8 o
[o] V
o o , 9 * # - Fj©-S -OCH-3 g °°g g ô
(64)
It is quite possible that ri^-CsHjFe(CO)aS(0)0CH3 is initially formed in the alkylation, but it is then oxidized to the methylsulfito complex.
Oxidation must occur in the reaction since [n^-C5H5Fe(CO)aS02]2 is also one of the products. Both r|®-CsH5Fe(C0)aS(0)20CH3 and
[ri^-CsHsFeCCO)2 SO2 ]2 are also prepared when K[ri®-CsH5Fe(C0)2S02] and
(CH3 )3 0 PF6 react in refluxing methylene chloride.
Attempts toward the preparation of phosphine substituted complexes of the type, ri^-C5H5Fe(C0) (PPh3 )S(O)aOR, were unsuccessful.
A proposed metathesis between ri®-C5HsFe(C0) (PPhs)! and Na[S(0)aOCH3] led to decomposition materials. When ri®-C5H5Fe(C0)aS(0)2 CH2 CH=CH2 was irradiated in the presence of PPhs, the iron complex was decarbonylated to form n“-C5H5Fe(C0)(PPh3)S(0)aCH2GHa=CHa (102). Irradiation of a solution of n’-CsHsFe(CO)2 8 (0 ) 2 0 0 1 1 3 and PPhs resulted in degradation of the iron complex. Recently, a few metal carbonyls have been decarbonylated with (CH3 )aN0 (1 0 2 ), but addition of (CH3 )3N0 to a 123 solution of n’-CsH5 Fe(C0 )2 S(0 )2 0 CH3 and PPhs resulted in rapid decomposition of the methylsulfito complex.
A series of methathetical reactions between Na[S(0)20CHa] and metal carbonyl or nitrosyl halides resulted in the preparation of only one new methylsulfito complex. The complexes which failed to react with Na[S(0)2OCH3 ] were r)^-CsHsCr(N0 )2 Cl, W(CO)sI , and
Mn(C0 )3 (PPhs)2 l. However, reaction of Na[S(0 )2 0 CH3 ] and
ClMn(CO)3 (2,2'-bipyridine) yielded CH3 OS(0 )2Mn(CO)3 (2,2'-bipyridine):
ClMn(CO) 3 (2,2'-bipyridine) + Na[S(0)2 OCH3 ] (65) CH3OH
CH3 0 S(0 )2Mn(C0 ) 3 (2,2'-bipyridine) + NaCl
After the CH3 OH had been removed under vacuum, the resultant orange precipitate was extracted into CHCI3 . Concentration of the extract afforded CH3 0 S(0 )2Mn(CO)3 (2,2'-bipyridine) in high yield. The manganese complex was identified by NMR and infrared spectroscopy. The NMR spectrum (acetone-de) shows a resonance at T 7.33 for the CH3 protons and a multiplet between T 0.93-2.28 for the 2,2'-bipyridine protons.
The infrared spectrum (KBr) exhibited numerous peaks attributable to
2,2'-bipyridine, v(CO) bands at 2054 and 1940 cm“ ^, v(S0 2 ) bands at 1198 and 1077 cm“ ^, and a V(C-O) band at 955 cm“^.
The V(S0 2 ) bands for CH 3 0 S(0 )aMn(CO)3 (2 ,2 '-bipyridine) are found at lower energy than those in ri®-C5 HsFe(C0 ) 2 S (0 ) aOCHa, which occur at 1214 and 1095 cm“^. Owing to the basicity of the 2,2'-bipyridine ligand in
CHaOS(0)2Mn(C0 )3 (2,2'-bipyridine), an increase in it bonding between the manganese and the methylsulfito ligand is necessitated. The increase in 124 electron density on the methylsulfito ligand lowers the S-0 bond order and shifts the S-0 stretches to lower wave numbers.
B. Reactions of the Metal-Alkylsulfito Complexes
Transestérification Reactions
The alkylsulfito complexes n^-CsH5 Fe(CG)2 S(G)2 ÛR are structurally similar to organic sulfonic esters, R'S(G)2 GR*'. Ethers result when sulfonic esters are heated with alcohols (54).
R'S(G)2GR” + R ' " G H t R'SGaH + R " G R " ' (66)
The sulfonate ion RSG3 , is such a good leaving group that the ester readily alkylates the alcohol.
When the alkylsulfito complexes were heated in alcohols, transestérification occurred rather than alkylation.
n’-C5 H 5 Fe(CG)2 S(G)2 GR + R'GH (excess) ^ (67)
n'-C5HsFe(CG)2S(G)2GR’ + RGB
R = CHa, R' = C2H5
R = C2H5, R' = CHa
The reactions were complete in 24 hours, but as indicated by the low product yields (53-65%), the elevated temperatures caused some decomposition. It should be mentioned that the exchange is not effected at 25°C or in the presence of a radical initiator (benzoyl peroxide). 125
In the presence of small amounts of HBFi, (ri“-CsHsFe(C0 )2 S(0 )2 0 R/
HBFi, molar ratio ) 30/1), the interconversion of the alkylsulfito
complexes was accomplished in shorter reaction times ( 1 2 hours),
n“-CsHsFe(C0)2ÛR + R'GH n^-C5HsFe(C0)2S(0)20R' + ROH (6 8 ) HBFt
R ~ CHa, R* = C2 H 5
R “ C2 H 5 , R* — CH3
under milder conditions (25°C), and in higher yields (75-84%) than
the thermal transestérifications. The acid-promoted exchange
was general for alcohols, but both phenol and p-toluenethiol failed
to exchange. Also, the exchange did not take place under basic
conditions.
In order to determine the mechanism of the acid-promoted
exchange, a reaction was carried out between ri®-CsH5 Fe(C0 )2 S(0 )2 0 CH3
and a five-fold excess of optically active (+)se9 -2 -octanol([a] | 8 9 ® =
+8.75°) in the presence of HBF4 . After work-up of the reaction mixture by column chromatography on Florisil,
(+)5 8 9 -ri*-C5 HsFe(C0 )2 S(0 )2 0 CH(CH3 ) (C6H 1 3 ) was obtained in high yield. 126 ç O HBF4 Fe-ë-O-CH^ + (+%8g-2-CgH-,-70H C O o
(69)
F © “S - O - Cq H + CH3OH
The 2-octylsulfito complex was characterized by NMR (Table 8 ) and infrared spectroscopy (Table 6 ), and it was found to exhibit O optical acvitity, [ajssl^ = +23.8°. The 2-octylsulfito complex was then converted by action of CHaOH and HBF<, back to n-CsHsFe(0 0 )2 8 (0 ) 2 0 0 1 1 3 and 2 -octanol, which exhibited essentially O unchanged rotation, [a]fs9 = 8.60°.
o
Ç 9 H B F 4 Fe-S-O-CgH^y + CH3OH = 0 CO O
8 0
Fe-à-0-CH3 + (+)589'2-CgH-|yOH
Ô^ Ô ^ p -,21|21 ® O ' [‘^]roq=589 + 8.60° (70) 127
When (+)5 B9 -ri*-CsH5 Fe(C0 )2 S(0 )2 0 CH(CH3 )(CeHia) was refluxed in CH3OH, O (+)se9 -2 -octanol ([ajgea = 8.40°) was recovered. These experiments were designed to determine the site of bond cleavage in the alkysulfito ligand and in the exchanging alcohol. Since (+)-2-octanol is recovered with little, if any, racemization, the integrity of the O-C linkage in
the 2 -octoxy group must be preserved through the course of both exchange reactions (Equations 69 and 70). If the O-C linkage in the 2-octoxy group had been cleaved, the recovered octanol in Equation 70 should have been racemized because of inversion at the cleaved carbon of the octyl group. Since the O-C bond remains intact, the 0-H bond of the exchanging alcohols and the S-O(R) bond of the alkylsulfito ligand must rupture. A reasonable mechanism which accords with these results and which accounts for the acid promotion is depicted below:
o o Ç O-H _H+ /As 9 9
O O (71)
R — CHs , R' = (^") s B9 “ 2 —CeH1 7
A feature of interest in this mechanism is the involvement of the cationic iron-sulfur dioxide complex, [r)*-CsH5 Fe(C0 )2 S0 2 ]"*'. The 128 formation of it is not unreasonable, since a cationic manganese carbonyl-sulfur dioxide complex has been recently synthesized (8 ):
MnfCO):! + AgAsFs + SO2 [Mn(CO)sSOa]AsF« + Agl+ (72)
In this study the iron-sulfur dioxide complex [r)®-CsH5 Fe(C0 )2 S0 2 was prepared (in situ) by analogy with Equation 72.
? s o 8 Fe-I . AgBF^ [^,fe-s;:°]BF4 -Agi C ’ “10“C . 'O o o (73)
Over a period of a few hours the liquid SO2 solution slowly changed from the purple color of the r^-CsH5 Fe(C0 )2 l complex to a bright red color which is indicative of [Ti^-CsHsFe(C0 )2 L]'^ (L = neutral ligand)
(67,68). -ethanol was added to the red solution, which was then allowed to warm to 25°C. When the reaction mixture was worked-up by column chromatography on Florisil, Ti^-C5 HsFe(C0 )2 S(0 )2 0 CH3 was isolated as a product.
V 01 i.-io°c ^v9 Fe-s:^ BF4 + MeOH = 0 ^Fje-S-OCH- c: "o J 2. 25°C ^ o ^ o (74)
The preparation of the methylsulfito complex by this method lends strong support to the proposed exchange mechanism. Since SO2 is a
Lewis base in [Ff-C5 HsFe(C0 )2 S0 2 ]^\ the empty pd orbital on sulfur apparently exhibits high reactivity toward alcohol nucleophiles. The 129
Iron is positively charged in the complex, and it should activate the empty sulfur pd orbital by removing some electron density from SO2 .
The AgBF* used in Equation 74 contained a slight amount of water as indicated by infrared spectroscopy even after heating at 145°C/1 torr for 1.5 hours. Under these rather severe conditions the AgBF* darkened slightly, probably as a result of some decomposition. The presence of water may have interferred with the formation of [ri^-CsHsFe (CO)2 SO2 by giving [r^-CsHsFefCOjgU^O]^^ (6 8 ), and as a consequence, only a 29% yield of ri^-C5 H 5 Fe(C0 )2 S(0 )2 OCH3 was obtained.
It is also interesting to note that [n^-C5 HsFe(C0 )2 S0 2 ]^ represents the third member in the series [ri®-CsH5 Fe(C0 )2 S0 2
(n = -1, 0, +1), This range of oxidation states of a metal with the same ancillary ligands demonstrates the amphoterism and high reactivity of S0 2 toward transition metal complexes. When SO2 coordinates as a
Lewis acid to give [ri'-CsHgFe(0 0 )2 8 0 2 ] , the lone electron pair on sulfur is subject to alkylation (Equation 16). This results from a build up of electron density on the SO2 moiety owing to the basicity of the metal complex. Although [ri®-C5 HsFe(C0 )2 S0 2 »] has not been isolated, the formation of it is highly probable in the photolysis of
[ri°-CsH5 Fe(C0 )2 ] 2 and SO2 (Equation 41) because [r|®-CsH5 Fe(C0 )2 S0 2 ] 2 is obtained as a product. Finally, as demonstrated above, SO2 is activated toward alcohol nucleophiles in [ri“-C5 H 5 Fe(C0 )2 S0 2 ]'^. The series of iron-sulfur dioxide complexes also shows that the metal plays an important role in the reactivity of ligated SO2 . 130
Preparation and Reactions of ri°-C5H3Fe(C0)aS(0)20H
Hydrolysis of sulfonic acid esters, RS(0)20R', proceeds smoothly
with water or dilute base (104,105).
0 0 II . II R-S-O-R' + HaO R-S-OH + R'GH (75) II II 0 0
Except when R' is an aryl group, hydrolysis proceeds with R'-O bond
cleavage and inversion at R' (104,105).
Hydrolysis of ri®-C5H5Fe(C0)aS(0)aOR (R = CHa, CaHs) for 16
hours at 25°C affords ri^-C5HsFe(C0)aS(0)a0H in high yield (the
deuterium analogue was obtained in DaO):
(rp-C5H5)Fe(C0)2S02(0R) + H 2O Fe + ROH
R z C H g . C g H ^ O (76)
The bisulfite product was identified by elemental analysis and
spectroscopic methods. The infrared spectrum (KBr), reproduced in
the 1300 to 700 cm"* region in Figure 10, contains CO stretching
frequencies at 2062 and 2018 cm"*, SOa antisymmetric and symmetric stretching frequencies at 1184 and 1038 cm"*, respectively, and a
S-0 stretching frequency at 811 cm"*. A broad peak at 2940 cm"* is assigned to V(O-H). Detoni and Hazdi (106) reported that v(OH) is found ca. 2900 cm"* for sulfonic acids, and for the deuteriated Fe-S-O-H
1300 1200 1100 1000 9 0 0 8 0 0 7 0 0 FREQUENCY (CM“')
Figure 10. Infrared spectrum (KBr) of n^-CsH5Fe(C0)2S(0)20H
in the 1300 to 700 cm ^ region.
U) 132 acids, V(OD) is found aa. 2225 cm"*. In accord with these results, the infrared spectrum of rf-C5HsFe(C0)2S(0)20D shows a V(OD) peak at 2230 cm”*.
The *H NMR spectrum (DMSO-d,) shows two resonances: at 4.70 T for the CsHs protons and a broad peak at -1.16 T for the bisulfite proton. For anhydrous sulfonic acids, the resonance for the acid proton is observed between t = -2 and -1 (107).
The bisulfite complex represents the first well characterized organometallic analogue of organic sulfonic acids, RS(0)2ÛH. On the basis of elemental analysis and an infrared spectrum. Field and
Newlands (27) tentatively proposed a formulation of n^-CsH5 Fe(C0 )2 FeS0 3 H*H2 0 for one of the thermal reaction products of
[ri®-C5H5Fe(C0) 2 ] 2 and SO2 . A bisulfite ligand is implied by this formulation, but the reported spectrum contains only two possible
V(SO) stretching frequencies: a band of medium intensity at 1244 cm"* and a strong absorption at 960 cm”*. However, a bisulfite ligand
(co-ordinated to the metal through sulfur) should exhibit three strong peaks: two v(S02) bands of equal intensity, and a V(S-O) band.
Alternatively, if the species was considered to be a sulfite complex,
[ri®-C5 HsFe(C0 )2 FeS0 3 ] , the sulfito ligand could be attached to the metal through the sulfur or through two of the oxygens in a bidentate fashion (108). Sulfito groups which are S-bonded (local C3 V symmetry) exhibit two S-0 stretching frequencies: a broad peak between 1150-
1050 cm"* and a sharp peak at 960 cm”* (108). Bidentate sulfito groups (local symmetry) give rise to three stretching modes (108).
Since neither a peak between 1150-1050 cm”* nor three peaks were 133 reported for n“-C5 HsFe(C0 )2 FeS0 3 H»H2 0 , the formulation of this complex as a species with a sulfite or bisulfite ligand appears to be incorrect.
The hydrolysis reaction (Equation 76) is reversible, and n®-CsH5 Fe(C0 )2 S(0 )2 0 R (R = CHg, C 2 H 5 , CHCCHa)(CeHia)) may be regenerated in high yields by treatment of ri®-CsHsFe(C0 )2 S(0 )2 0 H with the appropriate alcohol for 24 hours at 25°C.
n“-C5HsFe(C0)2S(0)20H + ROH -»■ n^-CsHsFe(CO)aS(0)2 OR + H 2 O (77)
Reaction 77 proceeds with the preservation of the 0-R bond of the alcohols and cleavage of the S-O(H) bond of the bisulfite ligand.
These results are derived from the observation that when
(+)s8 9 -2 -octanol was the exchanging alcohol,
(+)5 e9 -0 ^-C5 H 5 Fe(C0 )2 0 CH(CH3 )(CeHia) was the product of reaction.
As shown in Equations 69 and 70, (+)5 B9 -Tl^-C5 H 5 Fe(G0 )2 0 GH(CH3 )(CeHia) was formed by transestérification of ri“-G5 H 5 Fe(G0 )2 S(0 )2 0 GHa with
(+)5 B9 “2 -octanol. The transestérification was found to occur with
S-O(GHa) bond scission in the methylsulfito ligand. Since
(+)589-ri^“G5H5Fe(G0)2S(0)20GH(GH3) (GeHia) was the product in
Equation 77, the S-O(H) bond of the bisulfito ligand and the 0-H bond of (+)3 B9 -2 -octanol must rupture in the course of reaction. This S-0 bond cleavage is in contrast to R'-O bond cleavage (except where
R* = aryl) in the hydrolysis of RS(0 )2 0 R' (104,105).
When an aqueous solution of r)®-G5 H 5 Fe(G0 )2 S(0 )2 0 H was titrated with NaOH to a pH = 7.00, the equivalent weight of the complex was determined to be 260 g /mole (Gale, for G7H6FeOsS:258). Figure 4
(page 78) shows that the shape of the curve for the titration of 134
n®-CsHsFe(C0 )2 S(0 )a0 H with NaOH is similar to those obtained for
strong acid-strong base titrations; as NaOH was added, the pH very
gradually changed as the equivalence point was approached, and then the
pH changed markedly at the equivalence point (109). This supports the
analogy between r|®-CsH5 Fe(C0 )2 S(0 )2 0 H and sulfonic acids, since both
display strong acid behavior (54).
Removal of H 2 O from an aqueous solution of ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 H
neutralized with NaOH affords the yellow, air-stable solid,
Na[n'-C5 HsFe(C0 )2 S0 3 ].
n=-C5 HsFe(C0 )2 S(0 )2 OH + NaOH -> Na[n®-C5 H 5 Fe(C0 )2 SO3 ] + H 2 O (78)
The sulfite complex is a 1:1 electrolyte in CH3OH (A^ = 70 ohm“ ^ cm®
mole” ^) (110), and its infrared spectrum (KBr) exhibits terminal
carbonyl bands at 2050 and 1994 cm“ ^, and S-0 stretching absorptions
at 1129, 1107, 1084, 1072, and 984 cm~^ (Figure 11). The absorptions at 1129, 1107, 1084, and 1072 probably result from splitting of the
E mode of the antisymmetric S-0 stretching vibration for sulfur bonded S0 3 ®“ (C3 v local symmetry) (108) and solid state effects. The band at 960 cm“ ^ is assigned to the symmetric S-0 stretching vibration
(108).
In a typical acid-base reaction ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 H reacted
in a 1 : 1 fashion with (C2 Hs)2 NH in acetonitrile to yield a yellow, air-stable solid, (C2 H 5 )2 NH2 [o“-CsHsFe(CO)2 S0 3 ].
25°C n=-C,HsFe(C0)2S(0)20H + (C2 Hs)2 NH (C2 H5 )2 NHa [q’-CsHsFe(CO)2 SO3 ]
(79) Na [' Fe-:
1300 1200 1100 1000 900 8 0 0 700 FREQUENCY (CM’')
Figure 11. Infrared spectrum (KBr) of NaEn’-CsHsFe(0 0 )2 8 0 3 ] in the 1300 to 700 cm~^ region.
w Ln 136
The predominant features in the infrared spectrum (KBr) of
(C2 H 5 )2 NHa[n“-CsHsFe(0 0 )2 8 0 3 ] are terminal carbonyl peaks at 2030 and
1990 cm”^ and numerous S-0 stretching frequencies between 1110 and
962 cm“^ due to the antisymmetric and symmetric S-0 stretching vibrations of the SOa®" ligand (108).
In the NMR spectrum (acetone-de) of (C2 H 5 )2 NH2 [ri°-C5 H 5 Fe(C0 )2 S0 3 ], the three resonances for the protons in the (CH3 CH2 )2 NH2 cation are all broad and ill-defined, but the resonance at 4.96 T for the C5H5 protons is sharp (Table 9). When two drops of D 2 O were added to the acetone-de solution as shown in Figure 12,the methyl and methylene proton resonances of the ethyl group sharpened to a triplet and quartet at 8.70 T (J = 7 Hz) and 6.76 T (J = 7 Hz), respectively. The resonance for the two ammonium protons disappeared owing to rapid exchange with D 2 O. Similar results were reported for the ^H NMR spectrum of (C2 Hs)2 NH 2 Cl (1 1 1 )J three broad resonances for the
(C2 Hs)2 NH2 ^ cation were recorded in acetone-de» but, when a drop of
D 2 O was added, the broad peaks for the methyl and methylene protons sharpened to a triplet and quartet at 8.73 T and 6.90 T, respectively, and the resonance for the ammonium protons disappeared.
The complex K[n°-C5 HsFe(0 0 )2 8 0 2 ] was prepared by reaction of
K[n“-CsH5 Fe(G0 )2 ] and SO2 (24). Since the [n^-C5 H 5 Fe(C0 )2 ]" anion is a very powerful nucleophile (2 2 ) and SO2 is only a weak electrophile,
[ri®“CsH5 Fe(C0 )2 S0 2 ]~ has sufficient basicity that it reacts with
CHsI to form r)“-C5 HsFe(C0 )2 S(0 )2 CH 3 (24). Both complexes
M[ri^-C5 H 5 Fe(C0 )2 S0 3 ] (M = Na, (C2 Hs)2 NH2 ) may be considered to be adducts of M[n“-CsH5 Fe(C0 )2 ] and SO3 , which is a much stronger Lewis 137 TABLE 9
NMR SPECTRA FOR Min’-CsHsFeCCO)2SO3]
Complex Chemical Shift(t ) Intensity Assignment
M = Na 4.95 s^ 5 C3 H 5
M = (CgHsjgNHz 1.88 br^'C 2 NH 4.96 s 5 CsHs 7.04 br 4 CHa 8.62 br 6 CH 3
M = (OzHsïzNHz 4.83 s* 5 CsHs 6.96 t (J = 7 Hz) 4 CH 2 8.70 q (J = 7 Hz) 6 CH3
M = (CHsizNHz 0.92 br^'C 2 NH 5.00 s 5 CsHs 7.43 s 6 CH 3
0 3 0 /(0 0 3 ) 2 0 0 solution. Abbreviations; s, singlet; t , triplet; q, quartet; br, broad.
^OOOls solution.
^Position of signal varies slightly with concentration. 138
Figure 12. NMR spectra of (C2 H 5 ) aNHa [n’-CsHsFeCCOaSOa]
in A) acetone-dg and B) acetone-dg/DaO with TMS
as internai standard. F e - S O
(B) TMS
(A)
10 T LO VO Figure 12 140 acid than SO2 . Consistent with this analogy, Na[n“-CsHsFe(CG)2 S0 3 ] was found to be unreactive with CH3I, even on heating at reflux in acetone/ethyl alcohol for 1 0 hours.
Reaction of r]°-C5 HsFe(C0 )2 S(0 )2 0 R with Amines
In general, esters of sulfonic acids alkylate amines in a one to one fashion with scission of the 0-R bond of the ester to form the ammonium salt rather than with scission of the S-0 bond to form the sulfonamide (54):
R'S(0)2NRa " ’ + R " O H
R'S(0)aOR' ’ + R2 ' "N H
R " (R " ' ) 2NH[R'S03] (80)
Dissolution of n^-CsHsFe(0 0 ) 2 8 (O)aOR in excess R2NH (R = CH3,
C2H5) at 25° led to a slow darkening of the solution from yellow to brown, and, within 20 minutes, a yellow precipitate formed. After the precipitate was collected by filtration and recrystallized from
CHCl3 /cyclohexane, the yellow, air-stable solid was characterized by spectroscopic and chemical methods as R 2 NH2 [ri°-C5 HsFe(C0 )2 S0 3 ]
(R = CH3, C2H5).
( T |5 _ c g H ^ F e ( C 0 )2S 0 2 (0 R) + 2 R ^ N H (excess) = >
R 2 N H 2 FeCO) gSO^] + R3N(?)
RcCH^.CgHc, (SI) 141
The characterization of (CaH5 )2 NH 2 [ri®-CsH5 Fe(C0 )2 S0 3 ] was previously discussed on page 136. The predominant features exhibited for
(CH3 )2 NH2 [n^-CsH5 Fe(C0 )2 S0 3 ] in the infrared spectrum are two terminal carbonyl bands at 2040 and 1980 cm~^ and numerous S-0 bands between
1110 and 960 cm“^ for the antisymmetric and symmetric stretching modes of sulfur-bonded sulfite (C3 V local symmetry) (108). The NMR spectrum (CDCI3), listed in Table 9 and reproduced in Figure 13, contains three resonances: a broad peak at 0.92 T for the ammonium protons, a sharp peak at 5.00 T for the C 5 H 5 protons, and a sharp peak at 7.43 T for the CH3 protons.
Since the stoichiometry of the reaction was not 1:1 (moles of
R2 NH/n“-CsH5 Fe(C0 )2 S(0 )2 0 R), the products in Equation 81 were initially difficult to identify. When the NMR spectra of the products were recorded, integration of the peaks indicated that the product was of the type R2NH2[n^-CsHjFe(CO)2SO3], since the ratio of R/H/C5H5 was
2/2/1 rather than 3/1/1 if RsNH[ri®-CsH5 Fe(C0 )2 SQ3 ] or 2/0/1 if ri®-C5 H 5 Fe(C0 )2 S(0 )2 NR2 had formed. Due to the anomalous nature of the reaction in Equation 81 it was necessary to support the spectral formulation of the products with chemical evidence.
The strongest support for the formulation of the products in
Equation 81 is that (C2 H 5 )2 NH2 [r|’-CsH5 Fe(C0 )2 S0 3 ] results from a 1:1 reaction of n®-C5 HsFe(C0 )2 S(0 )2 0 H and (C2 H 5 )gNH (Equation 79). The product from reaction of (C2 H 5 )2 NH (excess) and ri®-CsHsFe(CO)2 8 (0 ) 2 0 0 2 1 1 5 exhibited identical NMR and infrared spectra as those obtained for
(C2 H 5 )2 NH2 [n’-CsHsFe(CO)2 SO3 ]. (CH 3 )2 NH 2 [ ^ F e - S 0 3 ] C O
TMS
0 7 8 10 T
Figure 13. NMR spectrum of (CH3 )aNH2 [n^-C5H5Fe(C0)2SO3]
in CDCI3 with TMS as internal standard. M N5 143
The dimethylsulfonamide complex ri°“CsH5Fe(C0)2S(0)aN(CH3)2 was prepared independently:
Na[n=-C,HsFe(C0)2] + ClS(0)2N(CHs)2 [n=-CsH,Fe(C0)2]2 THF (major)
n^-CsHsFeCCOaCl + n“-CsH3Fe(C0)2S(0)2N(CH3)2 (82)
(minor) (minor)
The products were separated by column chromatography on Florisil, and, although [ri®-C5 H 5 Fe(C0 )2 ] 2 was the major reaction product, ri®-C5HsFe(C0)2S(0)2N(CH3)2 was isolated in low yield. The infrared spectrum (Nujol) of the dimethylsulfonamide complex contains carbonyl bands at 2045 and 1985 cm“ \ SO2 antisymmetric and symmetric stretching frequencies at 1220 and 1064 cm” ^, respectively, and an S-N stretch at
933 cm“ ^ (112), whereas the NMR spectrum CDCI3 exhibits a resonance at 7.28 T for the CHs protons and a resonance at 4.82 x for the C5H5 protons. On the basis of the spectral data, sulfonamides clearly were not formed in Equation 81.
A few examples have been reported (113,114) in which 2 moles of amine were involved in an anomalous alkylation with sulfonic acid esters similar to that observed in Equation 80, i.e.j
C6HsS(0)20R' + 2R"NH2 ->■ R ” NHR’ + R^NHs [C6 H 5 SO3 ] (83)
R * = -CH=CH2
-CH2C(CH3)=CH2
-CH2CH=CHC6Hs 144
Equations 81 and 83 are similar in two respects; two moles of amine
are consumed and transamination occurs. It appears that transamination
is an important factor in Equation 81, since r^-CsH5 Fe(C0 )2 S(0 )2 0 C2 H 5
failed to react at reflux with (C2 Hs)3 N, an amine which is incapable
of transamination. Also, the reaction of R 2 NH and n^-C5 HsFe(C0 )2 S(0 )2 0 R
is not accelerated by the presence of a radical initiator, benzoyl
peroxide.
One very important observation for the reaction of
ri^-CsHsFe(C0 )2 S(0 )2 0 R with excess R 2 NH is that it proceeds with 0-R
bond scission of the alkylsulfito ligand whereap the transestérification
of Ti®-C5 H 5 Fe(C0 )2 S(0 )2 0 R with R ’OH under reflux or with acid assistance
proceeds with S-0 bond cleavage (Equation 71). Thus, the alkylsulfito
ligand displays two different sites of chemical reactivity.
Reaction of n^-C5 HsFe(C0 )2 S(0 )2 0 R with Electrophiles
The initial step in the proposed mechanism for the acid assisted
transestérification reaction (Equation 76) of r)®-C5 HsFe(C0 )2 S(0 )2 0 R with R'OH involves the protonation of the alkylsulfito ligand:
? j 1 = ; n -CuH5Fe(C0)2-S-0-R -r— n -C5HsFe(C0)2-S-0-R (91) 'i -« L À
The alkylsulfito ligand in ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 R (R = CHa, C 2 H 5 ) is also subject to alkylation: 145
S: 9 C H g C b 9 9 1 (C2H5)30PF6 Fe-S-O-R = 0 Fe-S-O-CjHg PFe C 6 25°C O
R = C H g , C 2 H ^
Addition of cyclohexane to the methylene chloride solutions results in
precipitation of the yellow, air-stable powders of
[n®-C5 H 5 Fe(C0 )2 (S0 (0 R)(0 C 2 Hs))]PF6 (R = CHa, C 2 H 5 ) in 60% yields. The
iron complexes represent the first examples of incorporation of
dialkylsulfites as ligands into metal complexes, but a few ethylene
sulfite complexes have been photochemically prepared (115-118):
hv M-CO .V + CO (85) II 0
M = n -C5 HsMn(C0 )2 , Cr(CO)s, W(CO),, n -C6 H 6 Cr(C0 ) 2
The new complexes which contain the dialkysulfite ligand
0 S(0 C 2 Ha)(0 R) (R = CH3 , C2 H 5 ) were identified by elemental analyses, conductivity measurements, and NMR and infrared spectral data. Both complexes [ri*"C5 HsFe(C0 ) 2 (S0 (0 C2 H 5 ) (OR) ) ]PFe are 1:1 electrolytes in
CHaN0 2 : for R = CHa, A = 9 6 ohmr^ cm“ mol"*, and for R = CH2 CH3 , m = 86.5 ohm” * cm® mole” * (110).
The infrared spectra (Table 10) of the complexes show V(CO) bands
Qa. 2080(s) and 2050(s) cm"*, a single V(S = 0) band oa. 1226(s) cm"* and a V(C-O-S) band ea. 989(s) cm” *. Also presented for comparison in TABLE 10
IMPORTANT STRETCHING FREQUENCIES IN [n^-CsHsFeCCO)2 (SOCOCzHj)(OR))iPFg COMPLEXES,
n^-C5HsFe(C0)2S(0)20R COMPLEXES, AND 0S(0CzHs)2.
— 1 Compound V(CO) v(SO) , v(C-O-S) cm
a [ri’-CsHsFeCCOzCSOCOCzHs) (OCHs^jPF 6 2085, 2050 1228 990
n^-CsHsFeCCOaSCOaOCHa’’ 2064, 2007 I2I4, 1095 971
[n^-CsHsFeCCO)2 (SOCOCaHs)2 )]PFs^ 2080, 2050 1224 998
n^-CsHsFeCCO)2 S(0)aOCaHs^ 2062, 2000 I2I4, 1088
0S(0C2Hs)2^ 1205 lOIO
Nujol mull. All absorptions strong.
KBr.
'Neat liquid. Refs. 106 and 121.
■t- 147
Table 10 are the infrared spectra of r)®-CsH5 Fe(C0 )2 S(0 )2 0 R (R = CH3,
C 2 H5 ) and 0 S(0 C2 Hs) 2 (119). The two v(CO) bands for
[ri®-CsH5 Fe(C0 ) 2 (S0 (0 C2 H 5 ) (0R))]PF 6 ( R = C H 3 , C2 Hs) are found at higher energy than those for ri’-C5 HsFe(C0 )2 S(0 )2 0 R (R = CH3, C2H5). The
éthylation of the alkylsulfito ligand results in a decrease in electron density at the iron. With this decrease at iron, less electron density is distributed to the orbitals of the C O ligands, and, as a consequence, the C O frequencies are found at higher energies. By analogy with free 0 S(0 C2 Hs)2 , the O S ( O C 2 H 5 )(OR) (R = CH3, C2H5) complexes also show single V ( S = 0 ) and v ( C - O - S ) bands (Table 10 ).
The NMR spectra of the [n^-C5 H 5 Fe(C0 )2 (SO(OC2H5)(OR))]PFe complexes, listed in Table 11, are compared with the spectra of ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 R in Figures 14 (R = CHa) and 15 (R = C2H5). Both figures show that the C 5 H 5 resonance is shifted downfield by about 0.5 T on éthylation of r)^-CsHsFe(C0 )2 S(0 )2 0 R. This downfield shift is attributable to an increase in positive charge at the iron and the position of the C5 H 5 resonance for [r)®-CsH5 Fe(C0 ) 2 (S0 (0 C 2 Hs)(0 R) ) ]Pp6
(for R = CH3, u = 4.15 and for R = C2H5, „ = 4.08) is in the region found for other [ri®-C5 HsFe(C0 )2 L]'^ species (L = neutral ligand)
(67,68).
Another feature of interest in the NMR spectra of the ethyl- methylsulfite (Figure 14) and diethylsulfite (Figure 15) complexes is the multiplet structure for the methylene protons of the ethyl groups oa. 5.5 T. Apparently, the methylene protons are stereochemically nonequivalent because there is no element of symmetry which intercon verts them (120). For diethylsulfite (Table 11) the methylene protons TABLE 11
NMR SPECTRA OF [n^-CsHsFeCCO)2 (SO(OC2 H 3 )(OR))]PFs COMPLEXES AND 0S(0CH2CH3>2
Relative Compound Chemical Shift(t ) Intensity Assignment
[tf-C5H5Fe(C0) 2(S0 (0C 2H s ) ( 0CH 3)) ]PFe^ 4.15 s 5 C5H5 5.67 m 2 CHa 5.97 s 3 OCH3 8.57 t (J = 7 Hz) 3 CH2CH3
[n=-CsH5Fe(C0)2 (S0(0C2Hs)2 )]¥¥e‘ 4.08 s 5 C 5 H 5 5.45 m 4 CHa 8.56 t (J = 7 Hz) 6 CH3
0S(0CH2CH3)2 5.97 m (J = 10.3 Hz, 2 0-C^H b CH3 J ’ = 6.9 Hz) 6.03 m (J = 10.3 Hz, 2 O-CH^HgCHa J" = 6.7 Hz) 8.74 m (J' = 6.9 Hz, 6 CH3 J" = 6.7 Hz)
(CÜ3)2C0 solution. Abbreviations: s, singlet; t, triplet; m, multiplet.
Neat. Ref. 120.
CO Â
c o o CH' TMS
_/
Ç 9 (A) W-Fe-S-O-CH-
8 ° ' -t~ -4— 6 7 8 9 10 f
Figure 14. Comparison of NMR spectra of A) n’~C3HgFe(C0)aS(0)a0CH3 and
B) [n’-CsHgFe(CO)a(SO(OCaHs)(OCH3))3PF6 in CDCI3 with TMS as Internal standard. KO 150
Fe-S-0-CoH= PR
TMS
(A)
10 r
Figure 1 5 . Comparison of NMR spectra of
A) n®-CaHsFe(C0 )3 S(0 )3 0 CaHs and B) In'-CsHsFe(CO)3(SO(OC3H,)3)]PF6
in CDCI3 with TMS as internal standard, 151
are also diastereotopic and rapid rotation about the S-O-C bands fails
to remove the nonequivalence of the methylene protons even at 120°C,
and an ABX3 type of splitting pattern is observed (120). An ABX3
splitting pattern could result in a 16 line spectrum for the methylene
protons (each of the 4 lines of the AB splitting pattern for the methylene
protons is split into a quartet by the three methyl protons) (1 2 2 ), but not all of the lines are resolved for diethylsulfite (1 2 0 ).
Similarly, in the NMR spectra of the ethyl methyl or diethylsulfite complexes, not all of the 16 lines for the methylene protons are resolved, and only a multiplet structure is observed.
The dialkylsulfite complexes [n^-C5 H 5 Fe(C0 )2 (S0 (0 C2 Hs)(OR))]PFe
(R = CH3, C2H5) were thought to be capable of exhibiting some alkylating properties. Although ketones are alkylated with reagents such as trialkyloxonium salts (123),
R' :C=0 + R/'aOBFt 4- /C-OR' BF4 + R i ' 0 (86) R > R' the NMR spectra of both dialkylsulfite complexes were recorded in acetone-d®, and there was no detectable interaction. However, in the same fashion as trialkyloxonium salts react with alcohols (123),
[n®-CsH5 Fe(C0 )2 (S0 (0 C2 Hs)2 )]PF6 alkylated C2 H5 OH:
o 8 0 Ç 0 Fe-S-O-C2 H 5 ] PF0+ C2H0OH ' = = v > e - S - 0 - C 2 H 5 C O O
(87) + ( ^ 2 ^ 5 )2 ^ * U P F g 152
After the volatiles were removed from the solution, an infrared
spectrum (Nujol mull) of the residue showed it to contain
ri®-CsHsFe(0 0 )2 8 (0 ) 2 0 0 2 1 1 5 and PFg . When the Nujol mull was exposed
to the air for 5 minutes, the r)'~C5 H 5 Fe(0 0 )2 S(0 )2 0 0 2 Hs was hydrolyzed
to ri*“C5 H 5 Fe(0 0 )2 S(0 )2 0 H, probably as a result of the hydroscopic nature of HPFg, which was formed in Equation 87.
n®-05H5Fe(00)2S(0)a0R + HgO n®0sH5Fe(00) 2 S (0) 2 OH (88)
+ ROM
Attempts at protonation of the alkylsulfito ligand in
Ti®-0 5 H 5 Fe(0 0 )2 S(0 )2 0 R with HOl or OF3OO2H led to cleavage of the
Fe-S bond;
n®-0 sH5Fe(0 0 )2 S(0 )20R + HX n^-CsHsFe(00)2X (89)
X = 01, OF3OO2
When HF was passed through a solution of n®-0 sH5 Fe(0 0 )2 S(0 )2 0 0 2 H 5 in
OHOI3, there was no reaction and rj®-05HsFe(00)2S(0)2002H5 was quantita tively recovered.
III. Preparation of Metal Oomplexes of the Ethyl Methanesulfinate Ligand
Wojcicki and Graziani (102) reported that the methylsulfinate ligand could be protonated at one of the sulfinate oxygens : 153
25 0 n*-CsH5Fe(C0)(P(n-C/.H9)3)S(0)2CH3 + HCl (91) CeHs
[n®-CsHsFe(CO)(P(n-CtH,)3 )(SO(OH)(CH,))]C1
Since the alkylsulfito ligands in n®-CsH5 Fe(C0 )2 S(0 )2 0 R are susceptible
to alkylation at one of the oxygens of the SO2 moiety (Equation 84),
the methylsulfinate ligand in ri®-CsHsFe(CO)(L)S(0)2CH3 (L = CO, PPh3) was also alkylated to prepare complexes containing the novel ethyl methanesulfinate ligand.
n=-CsH5 Fe(C0 )(L)S(0 )2 CH3 + (CH3CH2)3 OPF6 (92)
CH2 CI2
[n^-CsH5Fe(C0) (L)(S0(0C2Hs )(CH3))]PF6 + (02815)20
L = CO, PPha
The products [n^-C5 HsFe(C0 )(L)(8 0 (0 0 2 8 5 )(CH3 ))]PF6 (L = CO, 8 8 8 3 ) were identified by elemental analyses, conductivity measurements
(1:1 electrolytes in C8 3 NO2 ) (110), and ^ 8 NMR and infrared spectral data. The V(CO) and v(SO) bands in the infrared spectra of
[8 ^-0 5 8 5 8 0 (0 0 )(L)(8 0 (0 0 2 8 5 )(C8 3 ))]PF6 and 8 ^-0 5 8 5 8 0 (0 0 )(8 )8 (0 ) 2 0 8 3 are presented for comparison in Table 12. Figure 16 illustrates the differences in the 2200 to 1900 cm~^ and 1250 to 800 cm“ ^ regions of the infrared spectea when 8 ^-0 5 8 5 8 0 (0 0 )2 8 (0 ) 2 0 8 3 was ethylated to form
[8 ®-0 5 8 5 8 e(0 0 )2 (SO(0 0 2 8 5 )(0 8 3 ))]PF6 . It is apparent from both Table
12 and Figure 16 that the 00 stretching frequencies of the alkylated species occur at higher energy. The alkylated species have acquired a positive charge and, as a consequence, the amount of electron TABLE 12
COMPARISON OF IMPORTANT STRETCHING FREQUENCIES OF [n^-CgHsFeCCO)(L)(SOCOCaHs)(CH3))]PFs
COMPLEXES AND n’-CsHgFeCCO)(L)S(0)jR COMPLEXES
Compound V(C0)* v(S=0)^ V(S-O-C)^ cm ^
[n’-C5H5Fe(C0)2(0C2Hs)(CH3))]PF6 2077, 2040 1190 980
n=-C5HsFe(C0)2S(0)2CH3^ 2060, 1984^'C 1194, 1052
[u’-CsHgFeCCO)(PPha)(SOCOCaHg)(CHaDjPFg 1990 1188 968
n’-CgHsFeCCO)(PPh3)S(0)2CHa^ 1962^ 1152, 1025
^Nujol mull, except as noted. All absorptions strong.
^CHCla solution.
^Reference 81.
^Reference 102. 155
Figure 16. Comparison of the infrared spectra (Nujol)
of A) ri “CgHsFe(CO) 2 S (0) 2 CH3 and B) [n®-C5H5Fe(C0)2(S0(0C2H5)(CH3))]PF6 in the 2200 to 1900 cm“^ and 1250 to 800 cm“ ^ regions. 156
(A)
^ e - S - C H
(B)
#fe-S-CH3 PF(
2200 2000 1900 1200 1100 1000 900 800 FREQUENCY (CM"')
Figure 16 157
density located at the iron is decreased. In turn, less electron
density is distributed from the metal into the orbitals of the
carbonyl ligands, and the CO stretching frequencies are found at
higher energy. The alkylated species have only one V(S=0) band oa.
1189 cm“ ^, and a new band is observed oa. 975 cm” ^ for the v(C-O)
stretching frequency of the ethyl methanesulfinate ligand.
Table 13 lists the NMR resonances for the new complexes
En^-CsHsFeCCO)(L)(SOCOCaHs)(CH3))]PF6 (L = CO, PPha) and also the
resonances of ri^-CsHsFeCCO) (L)S(0 )aR and OSCOCaHs) (CHa) (124) for
comparison. The spectrum of [ri“-C5 H 5 Fe(C0 ) (PPha) (S0 (0 CaH5 ) (CH3))]PF6
is reproduced in Figure 17. In the NMR spectra of the ethylated complexes, the resonances of the ethyl methanesulfinate ligand were found to broad and unresolved. One feature in the NMR spectra which does stand out is that the C5 H 5 resonances are shifted downfield when the ri®-C5 HsFe(C0 ) (L)S (O)aCHa complexes are ethylated to form [n®-C5H5Fe(C0)L(S0(0CaHs)(CHg))]PF6 (L = CO, PPha). This downfield shift was also observed when the r|®-C5 H 5 Fe(C0 )aS(0 )a0 R complexes were ethylated to form [r)®-CsH5 Fe(C0 )a (SO(OCaHs ) (OR) ) ]PFe . TABLE 13
NMR SPECTRA FOR [n^-CsHsFeCCO)(L)(SOCOCaHs)(CHgllPFe, n^’-CsHaFeCCD)(L)S(O)aOR,
AND OSCOCaHs)(CH3)
Compound Chemical Shift(t ) Intensity Assignment
[n^'-CsHsFeCCO) 2 (SOCOCaHsXCH,)) ]PFe 4.39 br^ 5 C 5 H 5 5.66 s 3 S-CH3 6.40 br 2 CHa 8.56 br 2 CHaCHg c n=-C5 HsFe(C0 )2 S{0 )aCH3 ^ 4.75 s 3 CH3 6.55 s 5 C5 H 5 d 2.38 m 15 CeHs [n“-C5 HsFe(C0 )(PPh3 )(S0 (0 CaHs)(CH3 ))]PF6 4.76 s 5 C5H5 6 . 0 0 br 2 CHa 6.55 br 3 S-CH3 8.92 br 3 CHaCHa c 2.60 m 15 CfiHs n^-CsH5Fe(C0)(PPh3)S(0)aCH3® 5.35 d 5 C 5 H 5 7.45 s 3 CH3
H f c CH3S-0CaHs 6.02 q 2 CHa 7.52 s 3 S-CH3 8.74 t 3 CH2 CH3
^CDaCla solution. Abbreviations: s, singlet; d, doublet; t, triplet; m, multiplet; br, broad. ^ ^Ref. 81. ^CDCla solution. *^(CD3)aC0 solution. ^Ref. 102. ^Ref. 124. œ c O - C 2 H 5 Fe-S-CHo
TMS
7 8 10 T
Figure 17. NMR spectrum of tn^-CsHsFe(CO)(PPha)(SOCOCaHs)(CH3))jPFs in acetone-d, M with TMS as internai standard. Ln vo SUMMARY
As part of an investigation of the comparative chemistry of organometallic complexes containing sulfur-oxygen ligands, alkylsulfito compounds of the type ri’-CsH5 Fe(C0 )2 S(0 )a0 R were synthesized and examined. Efforts to expand the preparation of alkylsulfito complexes to other metal carbonyls or metal nitrosyls were marginally successful; only one other complex, CH3OS(0 )2 Mn(C0 )a(2,2'-bipyridine), was prepared.
Some emphasis was placed on the development of the chemistry of the alkylsulfito ligand in ri®-C5 H 5 Fe(C0 )2 S(0 )2 0 R complexes for comparison with the corresponding reactions of organic sulfonic acid esters.
The alkylsulfito complexes ri®-CsH5 Fe(C0 )aS(0 )2 0 R (R = CH3, C 2 H5 , n-CsHy, i-CsHy,) may be interconverted by use of the appropriate alcohol at reflux or at 25°C in the presence of a catalytic amount of
HBFi,. Reaction of n^-CsHsFeCCO) aS (0) zOCHa with (+)589-2-CeHi70H and
HBF4 followed by treatment of the optically active product
(+)5 e9 -n^-C5 H 5 Fe(C0 )2 S(0 )2 0 CeHi7 with CHaOH and HBF4 regenerates
(+)5 e9 -2 -CsHi7 0 H with unchanged specific rotation. This result is interpreted in terms of an acid induced cleavage of the S-O(R) bond of the alkylsulfito ligand and formation of a cationic iron-sulfur dioxide intermediate, [n'-CsHsFeCCO)2 S0 2 ]"*^. This complex was apparently formed in solution from n*-C5 HsFe(C0 )2 l and AgBF* in liquid
160 161
SO2 and was found to be reactive toward methanol to afford
n’-CsHsFeCCO)aS(0)2OCH3.
The formation of [ri^-CsHsFe(0 0 )2 5 0 2 ]"*^ adds a third member to the
series, [ri“-CsHsFe(CO)2 SO2 ]” (n = -1 , 0 , +1 ), which have been examined
in this work. As expected, these complexes exhibit a wide range of
chemical reactivity as a result of the different oxidation states of
the metal. The oxidation state of the metal exerts marked influence
on the reactivity of these complexes: [n^-CsHsFe(0 0 )2 8 0 2 ] reacts
with alkyl halides, RX, as a nucleophile to form r^-C5 HsFe(C0 )2 S(0 )2 R,
whereas [ri^-CsHsFe(0 0 )2 8 0 2 ]"*" reacts with alcohols, ROH, as an electrophile
to form rf-CsH5 Fe(0 0 )2 8 (0 )2 0 R.
Hydrolysis of ri^“0 5 HsFe(0 0 )2 S(0 )2 0 R proceeds with S-O(R) bond
cleavage to afford the bisulfito complex, ri®-C5 HsFe(C0 )2 8 (0 )2 0 H , which is
a strong acid. Treatment of n'-0 5 HsFe(CO)2 8 (0 )2 0 H with ROH regenerates
n^-OsHsFe(0 0 )2 8 (0 )20R.
Reactions of Ti^-OsHgFe(00)2 8 (0)2 OR with excess R 2 NH proceed with
scission of the SO-R bond unexpectedly to yield R2 NH2 [n^-OsHsFe(0 0 )2 8 0 3 ].
The SO-R bond cleavage is in contrast to the S-OR bond cleavage
observed for the interconversion of the ri^-OsHsFe(0 0 )2 8 (0 )2 OR complexes.
The alkylsulfito ligand in n*-C5H5Fe(00)28(0)20R (R = CH3, O2H5)
also exhibits sufficient basicity that it reacts with (0 2 Hs)sOPF6 to yield the first complexes which contain the dialkylsulfite ligands,
[n®-0 5 H5 Fe(0 O)2 (8 O(OR)(OC2 H 5 ))]PF6 (R = OH3, O2H5). Although these complexes do not alkylate acetone, they readily react with alcohol.
In a related alkylation, the methylsulfinate ligand in
H^-0 5 HsFe(CO)(L)S(O)2 OH3 (L = CO, PPhs) undergoes éthylation with 162
(CaHsïaOPFe to give the complexes [n 5 -CsHsFeCCO)(L)(SOCOCaHs)(CHa))]PFs which contain the first examples of ligated ethyl methanesulfinate. CONCLUDING REMARKS
A plethora of metal complexes containing sulfur-oxide ligands have been described in the literature. The range of ligands which are
solely composed of sulfur and oxygen is fairly extensive, and the
following sulfur oxides have been incorporated into complexes t sulfur monoxide, SO (125), disulfur monoxide, S2 O (126), disulfur dioxide, S2 O 2 (126), sulfur dioxide, SO2 (5,7-9,15,18-21,24-27), sulfite ion, SOa^“ (108), sulfate ion, SOi,^“ (5,9), and thiosulfate ion, 8 2 0 3 ^“ (127-129). A new member was added to the list above, as the complexes [M-JS(0)2 -S(0)2 -fM] (M = n^-CsHsFe(CO) 2 , Mn(CO)s, and
Re(CO)5 ) which contain the dithionite ligand, S2 O 4 '", were prepared and characterized in this study.
Numerous neutral and ionic organo-sulfur-oxide species have also been incorporated as ligands into metal complexes: dialkyl and 9 ------I > diarylsulfoxides, R-S-R (115-118,130), sulfolane, CHaCHaCHaCHaS(0) 2
(131), ethylene sulfite, 0 =S0 CH2 CH2 0 (115-118), alkylsulfenate ion, 0 _ 0 R-S-~ (132), alkyl and aryl-S-sulfinate ion, R-S-0 (16,133), alkyl
9 - 9 - and arylsulfonate ion, R-S-0 (46,134), alkylsulfite ion, R-O-S- 6 p 6 (39-45,82), and alkylsulfate ion, R-O-S-0 (135). Although examples 6 of alkylsulfito complexes had been known (39-45), a general synthetic route to such complexes was developed in this study. Transformations
163 164
of the alkylsulfito ligand in ri“-CsH5 Fe(C0 )2 S(0 )2 0 R led to the
preparation of many other sulfur-oxide ligands. Hydrolysis of
n®-C5 HsFe(C0 )2 S(0 )2 0 R resulted in formation of rf-CsH5Fe(C0)2S(0)2 Neutralization of ri®-CsH5Fe(C0)2S(0)20H with NaOH afforded Na[r|®-C5 H 5 Fe(C0 )2 S0 3 ] which is a rare example of an organometallic complex containing the sulfite ligand. Ethylation of ri®-CsHsFe(C0 )2 S(0 )2 0 R with (C2 Hs)3 0 PF6 generated the first series of 0 complexes which contain dialkylsulfites (R-O-S-O-R) as ligands, [n°-C5HsFe(C0)2(OS(OC2H5)(OR))]PF6, although complexes of ethylene sulfite were known prior to this study (115-118). The methylsulfinate ligand in ri®-C5H5Fe(C0) (L)S(0)2CH3 (L = CO, PPh3 ) also proved to be sufficiently basic such that its reaction with (C2 Hs)3 0 PF6 afforded the first complexes containing the ethyl methanesulfinate ligand 0 (CH3-S-OC2H5), [ri®-C5H5Fe(C0)(L) (0S(0C2H5)(CH3)]PF6 (L = CO, PPha). Four new sulfur-oxide ligands have been reported in this study, and the properties of these ligands as well as the properties of known sulfur-oxide ligands were investigated and developed. A significant portion of this work dealt with the interaction of organometallic complexes and sulfur dioxide and the subsequent transformations of ligated sulfur dioxide. APPENDIX Mass Spectra of Organo-Transition Metal Complexes 165 166 TABLE 14 MAJOR MASS SPECTRAL PEAKS FOR [n®-CsH5Fe(C0)aS0a]2‘ m/e I Ion 354 16 [n'-CsHsFe(C0 ):]2 + 326 2 0 (n=-CsH:)2Fe2(C0)3+ 304 298 40 (n=-C:Hs)2 Fe2 (C0 ):^ 270 36 (n'-CsHsiaFeaCCO) 258 256 242 80 (0 ^—C5 H5 )2 F6 2 2 1 2 186 90 (n=-C5 H 5 )2 Fe+ 177 90 n^-CsHsFefCO);* 156 148 72 n^-CsHsFeCCO)'*' 1 2 1 79 n^-CsHsFe’^ 83 85 65 1 0 0 C5 H5 * 64 > 1 0 0 SO2 * 56 Fe**" Source Temperature 80°C, 167 TABLE 15 a MAJOR MASS SPECTRAL PEAKS FOR [MnfCOÏsSOz]: m/e I Ion 390 >100 Mua(GO)10 362 2 MnafCO),* 322 5 306 . 1 278 2 266 2 250 >100 Mua(CO)s 222 >100 Mna(C0)4* 194 92 Mua(CO)3 166 80 MUa(CO) ^ 138 22 Mna(CO)+ 110 100 Mna"*" 64 >100 SOa^ Source Temperature 80°C. 168 TABLE 16 a MAJOR MASS SPECTRAL PEAKS FOR [Re(CO)sSOa]a m/e I Ion 654 24 Rea(CO)X 0 626 1 Rea(CO),+ 598 2 Re2(C0)8+ 570 58 Rea(CO),+ 542 30 Rea(CO).+ 514 20 Rea(CO),* 488 34 Rea(CO)q* 460 16 Rea(CO)a+ 432 20 Rea(CO)a^ 404 38 Rea(CO)^ 386 10 Re a C 374 32 Rea^ 244 2 Re(C0)4* 64 100 SOa^ Source Temperature 80°C. 169 TABLE 17 MAJOR MASS SPECTRAL PEAKS FOR COMPOUND "A"^ m/e I Ion 384 16 347 8 345 16 344 16 343 2 0 342 8 333 60 (n=-C5H5)w(co)3+ 313 2 0 305 50 (n=-C5 H 5 )w(co)z+ 277 42 (n^-C5H5)w(co)+ 249 1 0 0 (n^-C5Hs)w'^ 225 18 224 30 2 2 2 36 2 2 1 52 2 2 0 49 219 32 131 72 130 > 1 0 0 (C5 H 5 ) 2 129 > 1 0 0 128 > 1 0 0 6 6 > 1 0 0 CsHs* 65 > 1 0 0 CsHs+ 64 > 1 0 0 S02* ^ Source Temperature 120°C. 170 TABLE 18 MAJOR MASS SPECTRAL PEAKS FOR (n ^-CsHj)aMoaSaOa®’^ m/e I Ion 418 16 Cn^-CsH5)2**Mo2S202+' , 402 1 0 0 (n=-CsH5)2'*Mo2S20+ 386 4 (n=-C:Hs)2 **Mo2 S2 + 353 8 n^-CsHs **MO2 S2 0 2 + 337 44 n^-CsHs **M0 2 S2 0 + 321 16 '«M0 2 S2+ 258 44 257 2 0 256 32 2 0 2 14 2 0 1 8 2 0 0 1 1 199 7 96 1 0 **Mo+ 92 2 0 91 30 85 30 83 30 6 6 73 C 5 H 6 + 65 50 C 5 H 5 + a Source Temperature 80° C. ^ Assignment based on **Mo isotope, since there are 7 isotopes of Mo; 92, 94, 95, 96, 97 , 98, and 100. A binuclear complex, such as (t) “C5 Hs)2 Mo 2 S2 O 4 , with 7 isotopes for the metal exhibits a characteristic 15 line splitting pattern. 171 TABLE 19 MAJOR MASS SPECTRAL PEAKS FOR (n’-CsH») 2 ^“'‘WaOzSa^’^ m/e I Ion 594 100 (n=-CsH:)2'**W2S202* 578 92 (n:-C5Hs)2'*'W2S20+ 562 10 (n=-C5H5)2'*4W2S2* 529 32 n=-C5H5'=^W2S202^ 513 24 n=-c,H5i*^W2S20^ 498 32 (n:-C5H5)2**^W* 433 12 n=-C5H5'»4%2+ 342 16 287 12 286 24 214 12 183 17 168 15 . .100 22 86 34 66 34 65 98 C 5 H:* Source Temperature 140°C. Assignment based on isotope, since there are 5 isotopes of W; 180, 182, 183, 184, and 186. A binuclear complex, such as (n’-CsHs)2W2S202, with 5 isotopes for the metal exhibits a characteristic 11 line splitting pattern. 172 TABLE 20 MAJOR MASS SPECTRAL PEAKS For [(n=-C=Hs)3Fe3(C0)nS]BF\ (n = 4 or 5)* m/e I Assignment m/e I Assignment 428 2 185 2 354 6 (n*-C5Hs)2Fe2(GG)^‘^ 184 18 326 2 (n^-CsH5)2Fe2(C0)3+ 183 49 305 5 180 2 304 50 178 6 302 3 177 1 1 n^-CsHsFeCCO):^ 298 3 (n:-C5H5)2Fe2(C0)2^^ 150 8 277 4 149 7 n^-CsHsFeCCO)'^ 276 52 132 1 0 (CsHs) 2 274 4 1 2 2 28 249 4 1 2 1 > 1 0 0 n'-CsHsFe^ 248 60 95 2 2 242 1 0 (n:-C5H5)2Fe2^ 6 6 44 C 5 H 6+ 188 1 0 65 2 2 C 5 H 5 187 34 56 84 Fe'*' 186 1 0 0 (n:-CsH5)2Fe^ ^ Source Temperature 150°C. TABLE 21 MAJOR MASS SPECTRAL PEAKS FOR n^-C5HsFe(C0)zS(0)2 OR R = CH: R — CoHs m/e I Ion m/e I Ion 242 4 rf-CsHsFeCCO) S (0) 2 OCH3 '*' 286 2 n ^-CsHsFeCCO) 2 8 (0 ) 2 OC2 H 5 '*' 216 16 nS-C5H5FeS(0)20CH3^ 258 1 0 n S-CsHsFeCCO)S(0) 2 OC2 H 5 ''' 186 62 (n —C5 H 5 )2 Fe 230 40 ■ n^-CsHsFeSCO)2 0 0 2 8 5 ^ 177 32 n=-C5H5Fe(C0)2^ 186 80 (n=-C5H5)2Fe^ 149 42 n^-CsHsFeCof 177 41 n^-CsHsFe(C0 )2'^ 1 2 1 1 0 0 n^-CsHsFe* 149 40 rf-CsHsFeCO^ 103 28 1 2 1 1 0 0 fj^-CsHsFe 95 20 103 38 66 55 CsHe^ 95 38 65 23 C5 H 5 + 66 70 CsHe'*' 64 >100 S02^ 65 45 C 5 H 5 * 56 77 Fe"^ 64 >100 SOg^ 56 95 Fe^ Source Temperature 70*. Source Temperature 80°. w BIBLIOGRAPHY 1. G. W. Parshall, J. Mol. Cat., 4^ 243(1978), and references therein. 2. D. Sellman, Angew. Chem. Int. Ed., 13^ 639(1974), and references therein. 3. J. Chatt and G. J. Leigh, Chem. Rev., Z-, 121(1972). 4. F. A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry, Interscience Publishers, New York, 1972, p. 443. 5. G. J. Kubas, Inorg. 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