Sulfurization and Selenization of the Halfsandwich Nitrosylmetal Complexes Cp*M(CO)2NO (M = Cr, Mo) and Cp*M(NO)I2 (M = Mo, W) Max Herberhold*, Guo-Xin Jin Laboratorium für Anorganische Chemie der Universität Bayreuth, Postfach 101251, D-95440 Bayreuth Arnold L. Rheingold Department of Chemistry, University of Delaware, Newark, Delaware 19716, U.S.A. Dedicated to Prof. Dr. Dr. h. c. mult. E. O. Fischer on the occasion o f his 75 th birthday Z. Naturforsch. 48b, 1488- 1498 (1993); received June 8, 1993 Sulfido Metal Complexes, Selenido Metal Complexes, Halfsandwich Nitrosylmetal Compounds, X-Ray The photo-induced decarbonylation of Cp*Cr(CO)2NO in acetonitrile solution in the presence of excess sulfur leads to the cjWo-pentasulfido complex Cp*Cr(NO)(S5) (1 a), while in the case of limited sulfur supply the binuclear bis(//-disulfido) complex Cp*2Cr2(NO)2(/i-S2)2 (4 a) is formed preferentially. The corresponding reaction with elemental selenium produces Cp*2Cr2(NO)2(//-Se2)2 (4b), irrespective of the available amount of selenium. Photodecarbon- ylation of Cp*Mo(CO)2NO gives only the binuclear derivates Cp*2Mo2(NO)2(//-E2) (E = S (5 a), Se (5 b)) which are also obtained by treating Cp*Mo(NO)I2 with H2S or H2Se, respective­ ly. Nitrosyl loss predominates if the tungsten complex Cp*W(NO)I2 is reacted with H2S; in an argon atmosphere the products are Cp*W(S)(S2)(I) (7 a) and Cp*2W2(S)2(u-S)2 (8 a), while in air some Cp*W(NO)(S5) (3a) and the oxo compounds Cp*W(0)(S2)I (7c), Cp*2W2(Ö)2(//-S)2 (8c) and Cp*,W,(S)(0)(//-S)2 (8d) are formed. The analogous reaction with H2Se leads to Cp* W(NO)(Se5) (3b), Cp*2W2(0 )2(/z-Se)2 (9c) and Cp*2W2(Se)(O)0u-Se)2 (9d), respectively. The binuclear tungsten complexes 8a,c,d and 9c,d contain a central W(/i-E),W framework (E = S or Se) which is unaffected by air, while terminal sulfido and selenido ligands are quanti­ tatively converted into the corresponding terminal oxo ligands in the presence of air in CH2C12 or THF solution. With the preparation of Cp*2W2(0)2(//-E)2 (E = S (8c) and Se (9c)), the series of dioxo complexes containing a pair of monochalcogen bridges (E = O, S, Se, Te) has become complete. The new complexes have been characterized by their IR (v(NO)), 'H and 13C NMR (Cp*) spectra as well as by electron-impact mass spectrometry. According to the X-ray structure analyses, the binuclear compounds Cp*2Cr2(NO)2(//-S2)2 (4 a) and Cp*2Mo2(NO)2(//-Se2)2 (5 b) contain two 14-electron [Cp*M(NO)j fragments which are connected by a pair of dichalcogen (rj],tj2-E2) bridging ligands (M = Cr or Mo, E = S or Se). The central M2E2 four-membered ring is not planar, and the binuclear molecules are chiral.

Introduction We have recently described [1] the halfsandwich c^c/o-pentasulfido and cjc/o-pentaselenido com­ plexes la,b, 2 a and 3a,b which contain a nitrosyl ligand in addition to a voluminous pentamethyl- cyclopentadienyl ring: Cp*M(NO)(S5) Cp*M(NO)(Se5) 1 a: M = Cr (d’green) 1 b: M = Cr (black) 2 a: M = Mo (d'green) 3 a: M = W (violet) 3 b: M = W (black) Abbreviations: Cp = ^-cyclopentadienyl, 75-C5H<; Cp' = >75-methylcyclopentadienyl, ^5-C5H4Me; Cp* = ^-penta- methylcyclopentadienyl, //5-C5Me5. These compounds with a high chalcogen to met­ al ratio (5:1) are generally obtained [1] by treating The letters a and b in the numbering system refer to sul­ fur (a) and selenium (b) complexes, respectively. the halfsandwich nitrosyl complexes Cp*Cr(NO)2I and Cp*M(NO)I2 (M = Mo, W) with either meth- * Reprint requests to Prof. Dr. M. Herberhold. anolic ammonium polysulfide solutions or, in the Verlag der Zeitschrift für Naturforschung, D-72072 Tübingen case of selenium, with hydrogen selenide solutions, 0932-0776/93/1100- 1488/$ 01.00/0 generated in situ by hydrolysis of Al2Se3. However,

Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung This work has been digitalized and published in 2013 by Verlag Zeitschrift in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der für Naturforschung in cooperation with the Max Planck Society for the Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Advancement of Science under a Creative Commons Attribution Creative Commons Namensnennung 4.0 Lizenz. 4.0 International License. M. Herberhold et al. • Halfsandwich Nitrosylmetal Complexes 1489

side-products with a lower chalcogen to metal The intermediate acetonitrile complex has been ratio (mostly 2:1) are always formed as well. An characterized before [1]. Formation of the penta- alternative route to sulfldo and selenido com­ sulfido complex 1 a appears to be favoured; it was pounds is the photo-induced decarbonylation of obtained quantitatively in the presence of excess S8 the nitrosyl complexes Cp*M(CO)2NO (M = Cr, and still isolated in appreciable amounts when less Mo, W) in the presence of excess chalcogen. How­ sulfur was available. As expected, addition of S8 or ever, only la could be prepared by this method, (NH4)2Sx (jc ~ 10) to an acetonitrile solution of 4a whereas in the cases of molybdenum and tungsten, generates 1 a. products with lower chalcogen content were again The photodecarbonylation of Cp*Cr(CO)2NO invariably formed. in the presence of various amounts of selenium We now describe sulfurization and selenization ( 1 - 10-fold excess) produced only the binuclear reactions involving the Cp* halfsandwich nitrosyl­ complex 4 b. In a similar manner irradiation of metal complexes to give products of lower chalco­ Cp*Mo(CO)2NO in the presence of excess sulfur gen content. or selenium led only to the binuclear derivatives 5 a and 5b; pentachalcogenide compounds such as lb Results and Discussion and 2 a could not be isolated, although they are 1. Photodecarbonylation of Cp*M( CO) 2NO known [1], The monomethyl-cyclopentadienyl (M = Cr, M o) in the presence of sulfur or selenium complex Cp'2Mo2(NO)2(S2)2 was also prepared. Depending on the sulfur supply, the light- induced decarbonylation of Cp*Cr(CO)2NO may lead to' either Cp*Cr(NO)(S5) (la ) or Cp*2Cr2(NO)2(//-S2)2 (4 a) preferentially.

5/8 S8 • Cp*Cr(NO)(S5) 4 a: M = Cr (black) 4 b: M = Cr (black) 1a Cr hv,-CO_ £r -CO / 5 a: M = Mo (d’red) 5 b: M = Mo (black) 0 n " V " c 0 (CH3CN) 0 n " - ch 3cn 2/8 S8 - 1 /2 Cp‘ 2Cr2(NO)2(S2)2 The spectroscopic data obtained for 4a,b and Co c0 c h 3 4a 5a,b (Table I) are in agreement with binuclear

Table I. Spectroscopic data for the nitrosyl-containing complexes.

Compound IR (Csl) NMR (CDC13 solution) El Mass spectra {m e [%])a v(NO) ‘H >*C M + M +-2 N O - E M + -2N O -C p* [cm-1] (S values) (Ö values) M +-N O M +-2 N O - 2 E M + —2N O -E -C p*

4 a Cp*2Cr2(NO)2(jU-S2)2 1690 1.80s 10.1 (Me) 562(12% ) 470(15% ) 367 (2%) 1669 110.8 (ring) 532 (8%) 438 (96%) 502(100% ) 4 b Cp*2Cr2(NO)2(//-Se2)2 1664 1.89s 10.9 610(30% ) 555(10% ) 1626 119.7 720 (4%) 532 (50%) 690 (40%) 5a Cp*2Mo2(NO)2(Ju-S2)2 1652 1.87s 10.3 650 (23%)b 558 (68%) 455 (6%) 1645 112.9 620(15% ) 526(10% ) 423 (32%) 590(100% ) 5 b Cp*2Mo2(NO)2Gu-Se2)2 1641 1.93 s 10.9 840 (14%)b 700 (68%) 645 (8%) 1615 111.6 810(1% ) 620(10% ) 565 (21%) 780 (30%) Cp'3Mo2(N 0 ) 2(/z-S2)2 1652 2.1 Is (Me) 14.4 (Me) 538 (20%) 446 (98%) 399(12%) 1635 5.85m (1) 98.2 1 • 508 (25%) 414(14%) 367 (70%) 5.64 m (2) 95.4 } rmS 478(100%) 5.48 m ( l) 100.8(C )

a The m/e values listed refer to the isotopes 52Cr, 98Mo, 32S and 80Se; b FD mass spectra have confirmed the molecular masses of 5 a (m/e 650.1) and 5 b (m/e 840.1). 1490 M. Herberhold et al. ■ Halfsandwich Nitrosylmetal Complexes structures. Remarkably, in all cases two nitrosyl Stretching absorptions are observed in the IR spec­ / S \ .E ' tra, both in the solid state and in solution. This in­ .w — w E S dicates that the complexes cannot be centrosym- -O metric, although only one type of Cp* ring ligand is seen in the 'H and 13C NMR solution spectra. 7 a: E = S 8a: E = E' = S 7c: E = O 8c: E = E' = O The molecular structures of 4 a and 5 b were deter­ 8d:E = S, E' = 0 mined by X-ray crystallography (see below). The El mass spectra contain the molecular ion in all If the reaction of Cp*W(NO)I2 with H,S gas cases; the primary fragmentation process appears was conducted in air, several oxo complexes to be successive loss of the two nitrosyl ligands. such as 7 c, 8 c and 8d were isolated in addition to Attempts to desulfurize the pentasulfides 2 a and the only nitrosyl complex, Cp*W(NO)(S5) (3 a) 3a using PPh3 or PnBu3 gave binuclear complexes which was formed in low yield (2%). The prepa­ of the general composition Cp*2M2(NO)2S4 (M = ration of 3 a from Cp*W(NO)I2 and ammonium Mo, W). The molybdenum compound so formed polysulfide in moderate yields (72%) and the is not identical with 5 a. It is known that dechalco- structural characterization of the product have genation of Cp2Ti(E5) (E = S [2, 3], Se [4]) using been described earlier [1]. The mononuculear tertiary phosphanes leads to binuclear derivatives compounds Cp*W(E)(S2)I (E = S (7 a) or O (7 c)) containing a six-membered 1,4-dimetalla-cyclo- correspond closely to the methyltungsten com­ chalcogen ring. plexes Cp*W(E)(S2)Me (E = S, O) studied by Faller and coworkers [6]. - Cp -Ti: Binuclear complexes of the types Cp^ E ^ 'Cp Cp*2W2(E)(E')(//-S)2 (8a,c,d) are also known. In principle, several isomers are possible for complex­ E = S, Se es of the composition Cp*2M2S4, as has been shown for the case of both M = W [7] and, in par­ 2. Reaction of Cp*M(NO)I 2 (M = Mo, W) with ticular, M = Mo [7, 8, 9]. On the basis of the dark- hydrogen chalcogenide, H2E (E = S, Se) red colour and the similarity of the IR data When H2S gas was bubbled through the red (v(W = S), one single absorption at 486 cm“1, cf. THF solution of Cp*Mo(NO)I2, the main product 481 cm“1 [7]), there are good reasons to believe was Cp*2Mo2(NO)2(//-S2)2 (5 a) which could be iso­ that the binuclear complex obtained in the reac­ lated in about 80% yield. A similar reaction of tion of Cp*W(NO)I2 with H2S under argon is in­ Cp*Mo(NO)I2 with H2Se - obtained in situ by deed the anti-isomer 8 a first described by Brunner controlled hydrolysis of Al2Se3 in the THF solu­ et al. [7], The stepwise replacement of the two ter­ tion itself - led to the doubly Se2-bridged product minal sulfido by oxo ligands to give 8d and 8 c, re­ 5b in about 65% yield, although loss of NO to give spectively, in the presence of air is also in agree­ Cp*2Mo2Se4 (6b) was also observed. The green ment with the assumed W2S2 framework in the side-product 6 b is only sparingly soluble in organ­ binuclear Cp*W complexes 8a,c,d. ic solvents; its structure has not been determined but it is apparently different from the violet prod­ Cp' .s. Cp* ,s v Cp* s. ^w — JN —— uct obtained by Brunner et al. [5] by oxidative de- Cp* s'" Cp* Cp* carbonylation of Cp*2Mo2(CO)4 using excess se­ 8 d 8c lenium in toluene solution. Attempts to prepare binuclear nitrosyltungsten A similar conversion of a terminal sulfido into a complexes, analogous to 4a,b and 5a,b, were not terminal oxo ligand was observed in the case of the successful. The reaction of Cp*W(NO)I2 with H2S mononuclear 16-electron complexes 7 a, c. gas in THF solution in an argon atmosphere prod­ The reaction of Cp* W(NO)I2 with H2Se in THF uced both a brown-black mononuclear compound solution under argon gave a mixture of three prod­ Cp* WS3(I) (7 a) and a dark-red binuclear complex, ucts (3 b, 9 c and 9d), among which the mononu­ Cp*2W2S4 (8 a). clear cvc/o-pentaselenide 3 b is preferentially M. Herberhold et al. ■ Halfsandwich Nitrosylmetal Complexes 1491

That the oxygen-free complex (9 b) was not iso­ lated might be due to the presence of water as a re­ sult of the Al2Se3 hydrolysis. In air, 9d is rapidly and quantitatively converted to the dioxo complex 9 c. 7a The Cp*W compounds 8c,d and 9c,d have not ,W air (THF) been described previously. However, the CpW complexes (containing unsubstituted Cp ring ligands) Cp2W2(E)(E')0/-S)2 (E = E' = S [10, 11, 13], O [12, 13]; E = S, E' = O [13]) and j P-'. Cp2W2(E)(E')(yu-Se)2 (E = E' = O [14]) are well- known. At the present state of knowledge, it ap­ 7c pears that the binuclear tungsten complexes de­ scribed here generally prefer the anti-configura­ formed if the supply of H2Se is high. The binuclear tion containing the two Cp (or Cp*) ring ligands in compounds 9 c and 9d are typical products of lim­ mutual trans-position at a planar W2(//-S)2 or ited selenium supply. W2(//-Se)2 center. X-ray structure determinations carried out for Cp2W2(N'Bu)2(//-S)2 [13] and Cp2W2(0)2(//-Se)2 [14] have confirmed this trans geometry. (9b: E = E' = Se) 9c: E = E' = O The series of dioxo complexes Cp*2W20 2(//-E)2 9d: E = Se; E' = O is now known for all chalcogens as bridging ligands.

Table II. Spectroscopic data for the Cp*W complexes.

Compound IR(CsI) NMR(CDC13 solution) El Mass spectra (m/e [%])a Other [cm-1] >H 13C M + M +-E (<5 values) M + —2E

7 a Cp*W(S)(S2)I 498 v(S2) 2.38 s 12.8 (Me) 542(12% ) 510(90% ) 383(100% ) 485 v(W = S) 120.4 (ring) 478 (8%) M +- S - I 7c Cp*W (0)(S2)I 932 v(W = 0) 2.33 s 12.4 526(100%) 494 (7%) 399 (32%) 543 v(S2) 119.9 462(10% ) M +- I 8aC p*2W2(S)2(/i-S)2 486 v(W =S) 2.15s 766 (80%) 734(100% ) 631 (18%) M +-C p * 383 (21%) 8cCp*2W2(0 )> -S 2)2 920 v(W = 0 ) 2.25 s 12.2 734(100%) 718(5%) 599 (7%) 118.8 M +-C p * 367(3% ) 8d Cp*2W2(S)(0)(/z-S)2 911 v(W = 0) 2.35 12.2/12.9 749 (98%) 733 (100%) 615(9% ) 488 v(W = S) 2.17 119.7/115.6 M + - H M + —H —O M +-C p * 717(29% ) 375 (5%) M +- H - S 9c Cp*2W2(0 )2(//-Se)2 921 v(W = 0) 2.21 12.5 828(100% ) 812(4% ) 693 (44%) 112.5 M +-C p * 414(10% ) 9d Cp*2W2(0)(Se)(jW-Se)2 919 v(W = 0 ) 2.20 12.2/12.4 892(100%) 876 (23%) 757 (40%) b 2.31 111.0/112.7 812(15% ) M +-C p * 446 (45%)

a The m/e values listed refer to the isotopes 184W, 32S and 80Se; b a W =Se stretching absorption for 9d could not be observed (due to rapid hydrolysis to 9 c).

M. Herberhold et al. ■ Halfsandwich Nitrosylmetal Complexes 1493

Table IV. Selected bond distances and Bond distances [Ä] angles for Cp*2Mo2(NO)2(/i-Se2)2 (5b). M o -S e (l) 2.566(2) M o -N 1.762(13) M o-S e(2) 2.634(2) N-O 1.238(19) M o-Se(2a) 2.648(2) Se(l)-Se(2a) 2.311(2) M o-C p * 2.017( 15)a M o - Mo(a) 3.565

Bond angles [°] Se(l)-Mo-Se(2) 125.1(1) Mo-Se(l)-Se(2a) 65.5(1) Se(l)-Mo-Se(2a) 52.6(1) Mo-Se(2)-Se(la) 109.4(1) Se(2) - Mo - Se(2a) 75.9(1) Mo(a) - Se(2) - Se( 1 a) 61.9(1) Cp*-Mo-N 119.5(4)a Mo-Se(2)-Mo(a) 84.9(1) Cp*-Mo-Se(l) 113.2(4)a Se(l)-Mo-N 96.1(4) Cp*-Mo-Se(2) 111.2(4)a S e (2 )-M o -N 88.8(4) C p * -M o -S e(2 a ) 125.1 (4)a Se(2a)-Mo-N 114.9(4) M o - N - O 170.7(11) a Cp* = centroid of the five ring car­ bon atoms, C(l)-C(5). domness of the crystal selection process found spe­ The transannular distances (S(2) ••• S(2a) cimens which belong to different enantiomorphic 2.879Ä in 4a, Se(2)--Se(2a) 3.248 Ä in 5b) are space groups. The central four-membered ring has shorter than the sum of the van der Waals radii for a butterfly configuration; the dihedral angles in sulfur (2x 1.83Ä) and selenium (2* 2.00 Ä). As in Cp*2Cr2(NO)20u-S2)2 (4 a) are S(2)CrS(2a)/ related compounds (see below), the bond distances S(2)Cr(a)S(2 a) 124.4° (folded along S(2)-S(2a)) in the diatomic bridging ligands (S2 2.013(2)Ä in and CrS(2)Cr(a)/CrS(2 a)Cr(a) 115.7° (folded 4a and Se2 2.311 (2)Ä in 5a) are slightly shorter along Cr-Cr(a)). The corresponding dihedral an­ than the single-bond distances in S8 (2.06 Ä) and gles in Cp*2Mo2(NO)2(//-Se2)2 (5 b) have been Se8 (2.33 Ä), although considerably longer than the found to be Se(2)MoSe(2a)/Se(2)Mo(a)Se(2a) double bonds in the diatomic molecules S=S 117.7° (folded along Se(2)-Se(2a)) and (1.89Ä) and Se=Se (2.19Ä) [16]. MoSe(2)Mo(a)/MoSe(2 a)Mo(a) 112.9° (folded Binuclear complexes containing a pair of bridg­

along Mo-Mo(a)). Within the four-membered ing /i-rj\rj2 -E2 ligands are apparently formed if 8 ring the angles at the metal are acute (73.2(1)° in electrons are required to reach the inert gas config­ 4a, 75.9(1)° in 5b), and this can be taken as an in­ urations. Thus, uncharged complexes such as 4 a, dication that direct metal-metal bonding interac­ 5 b and 10 a [17] are composed from two tions are absent. 14-electron fragments:

[Cp*(NO)Cr](/j-S2)2[Cr(NO)Cp*] (4a) C r -C r 3.427 Ä s - s 2.013(2)Ä 14 el. 8 el. 14 el. [Cp*(NO)Mo](//-Se2)2[Mo(NO)Cp*] (5b) M o - M o 3.565Ä S e-S e 2.311 (2) Ä [Cp*Co](//-S2)2[CoCp*] (10 a) Co ••• Co 3.38Ä S-S 2.062(6)Ä

[19] are built from two 15-electron fragments: [Cp'(PPh3)Ru](//-Se2)2[Ru(PPh3)Cp']2+ (llb ) R u - Ru 3.937(1)Ä Se—Se 2.279(1)Ä 15 el. 8 el. 15 el. [(triphos)Rh](/z-S2)2[Rh(triphos)]2+ (12 a) S-S 2.022(3)Ä [(triphos)Rh](//-Se2)2[Rh(triphos)]2+ (12 b) S e-S e 2.298(1)Ä (triphos = MeC(CH2PPh2)3) 1494 M. Herberhold et al. ■ Halfsandwich Nitrosylmetal Complexes

An unsymmetrical structure made up from a 15- and a 13-electron moiety is observed in the Cp'Fe complex 13a [20]:

[Cp'(CO)Fe](//-S2)2[FeCp'] (13a) Fe-Fe 3.397(4) Ä

15 el. 8 el. 13 el. S -S 1.980(8) Ä 2.006(8) Ä

In contrast to 4a and 5b, the binuclear complex­ 983G; 'H and ,3C NMR: Jeol FX 90Q (CDC13, es 10a, llb and 12a,b are all centrosymmetric; the 0 °C); Mass spectra: Varian MAT 8500 (70 eV). two dichalcogen bridges are arranged anti X-ray: Nicolet R3m with graphite monochro­ (trans) with respect to the planar central four- mator. membered ring, at least in the solid state. However, the unsymmetrical iron complex a) Photo-induced decarbonylations in the presence [Cp'(CO)Fe](/*-S2)2[FeCp'] 13 a [20] and its ruthe­ of sulfur or selenium. Acetonitrile was used as a nium analogue [Cp*(CO)Ru](/*-S2)2[RuCp*] [21] solvent in order to keep most of the chalcogen appear to exist as an equilibrium mixture of both in solution anti (trans) and syn (cis) form in solution, as may Cp* 2 Cr2 (NO) 2 (m-S2 ) 2 (4 a) be deduced from two distinct v(CO) stretching ab­ An orange suspension containing 0.56 g (2.05 sorptions in the IR spectra-. The syn isomer of 13a mmol) Cp*Cr(CO)2NO and 0.18 g (5.6 mmol) sul­ has been structurally characterized; the four sulfur fur in 80 ml acetonitrile was irradiated 2 h at atoms are nearly coplanar [20]. 15 °C. Carbon monoxide evolved while the colour As may be expected from electron book-keeping of the reaction mixture changed gradually over red according to the inert gas rule, all these complexes and dark-green to black. The solvent was removed are diamagnetic, and the metal •••metal distances from the homogeneous solution in vacuo and the residue chromatographed on silica. Elution with are non-bonding. Discussions concerning the CH2Cl2/pentane (1:1) gave a dark-green zone con­ structural variety of Cp(*)M(E4)MCp(*) complex­ taining^ 0.18 g (23.3%) Cp*Cr(NO)(S5) (la ) [1], es and the electron accountancy for oligochalco- elution with CH2Cl2/pentane (2:1) a black zone genide bridging ligands may be found in recent containing Cp*2Cr2(NO)2(//-S2)2 (4 a). Black pris­ publications by Hoffmann [9], Rauchfuss [18] and matic crystals of 4a (0.36 g, 62.5%) were obtained W ächter [22], by slow diffusion of hexane into a chloroform so­ lution of 4a at -25 °C. The binuclear product 4a (m.p. 237 °C) is soluble in chloroform, dichloro- methane, acetonitrile, acetone and N,N-dimethyl Experimental formamide, but insoluble in saturated hydrocar­ All experiments were routinely carried out in an bons. atmosphere of dry argon using Schlenk tech­ niques. The use of dry and oxygen-free solvents is Cp* 2 Cr2 (NO) 2 (n-Se2) 2( 4b) necessary. An orange suspension of 0.33 g (1.21 mmol) The starting halfsandwich complexes Cp*Cr(CO)2NO and 0.19 g (2.42 mmol) gray se­ Cp*M(CO)2NO (M = Cr [23], Mo [1]) and lenium in 80 ml acetonitrile was photolysed for Cp*M(NO)I2 (M = Mo [1], W [24]) were prepared 3 h. The black reaction mixture was filtered and following established procedures. the concentrated solution chromatographed on sil­ The light source for the photolyses was a high- ica. Elution with CH2C12 produced a black zone of pressure 250 W mercury lamp (Original Hanau) 4 b. Crystallization from CHCl3/hexane at -2 5 °C housed in a water-cooled glass jacket. Separation gave 0.10 g (22.1 %) black needles which remained of product mixtures and purification of the com­ unchanged up to 250 °C. ponents was accomplished by column chromato­ graphy over silica gel (Merck 60) which had been Cp* 2 M o2 (NO) 2 (v-S 2) 2(5 a) activated at 600 °C overnight and stored under argon. Under irradiation the orange suspension of Spectroscopic measurements: IR: Perkin-Elmer 0.32 g (1 mmol) Cp*Mo(CO)2NO and 0.10 g (3.1 M. Herberhold et al. • Halfsandwich Nitrosylmetal Complexes 1495 mmol) sulfur in 50 ml acetonitrile became dark- dark-red zone containing Cp*2Mo,(NO)2(/*-Se2)2 red, and CO gas was liberated. After 1 h photolysis (5b) (0.28 g, 65,9%). the solution was concentrated and chromato­ 5b: C20H30Mo2N2O2Se4 (837.9), m.p. 165 °C (dec.) graphed on silica. A dark-red solution was eluted Calcd C 28.66 H 3.61 Mo 22.89 Se 37.68%, with CH2Cl2/pentane (1:1) from which 0.18 g Found C 28.31 H 3.52 Mo 22.4 Se 36.8 %. (55%) dark-red prismatic crystals of 5a could be isolated. Recrystallization from CHCl3/hexane at 6: C20H30Mo,Se4, no m.p. up to 250 °C -2 5 °C; m.p. 163-164 °C, soluble in polar organic >H NMR: <5(Cp*) 1.84. EI-MS: m/e 780 solvents. (M +, 100), 700 (Cp*-,Mo2Se3+, 40%), 565 (Cp*Mo2Se3+, 32%)." Cp' 2 M o2 (N O ) 2( p-S 2) 2, red prismatic crystals, m.p. 112 °C. Reactions with Cp* W (NO)I 2 Cp* 2 M o2 (NO) 2 (n-Se 2 ) 2 (5b) The photo-induced decarbonylation (3 h) of an 1. With H2S under argon: A stream of H2S was bubbled for 20 min through a solution containing orange suspension containing 0.32 g (1 mmol) Cp*Mo(CO)2NO and 0.32 g (4 mmol) gray seleni­ 0.30 g (0.5 mmol) Cp*W(NO)I2 in 50 ml THF. The colour changed from green to red. The solution um in 60 ml acetonitrile produced a black reaction was stirred for 1 h under argon, then brought to mixture. The solvent was taken off under reduced dryness in vacuo, and the black residue was worked pressure, and the residue was purified by chroma­ up by column chromatography on silica. Using tography on silica. Elution with CH2Cl2/pentane CH2Cl2/pentane (3:2) two bands were eluted, a (1:1) gave a dark-red zone which contained 5 b. brown zone containing Cp*W(S)(S2)I (7 a) followed Black prismatic crystals, m.p. 165 °C (dec.) after by a dark-red zone containing Cp*2W2(S)2(//-S)2 crystallization from CHCl3/hexane at -25 °C; (8a). Both products were recrystallized from yield 0.18 g (42.6%). chloroform/hexane at -25 °C to give 0.07 g (25.9%) 7a (black needles, m.p. 172-173 °C) and b) Reactions of Cp*M(NO)I 2 (M — Mo, W) with 0.09 g (47.1 %) 8a (dark-red crystals, no m.p. up to hydrogen chalcogenides, H2E (E — S, Se) 250 °C). Reactions with Cp*Mo(NO)I 2 2. With H2S in air: If the reaction of Cp*W(NO)I2 (0.60 g, 1 mmol) with gaseous H2S in Preparation o f Cp* -,Mo-,( NO ) 2( p-E 2 ) 2 (E = S(5a),Se (5b); THF solution (80 ml) was deliberately carried out under air, the chromatographic separation of the A stream of H2S gas was bubbled for 5 min product mixture gave four complexes: through the red solution of 0.52 g (1 mmol) Cp*Mo(NO)I2 in 100 ml tetrahydrofuran (THF). Cp*W(NO)(S5) (3a) [1], violet, 0.01 g (2.0%) The deep red solution was kept stirring for 1 h at Cp*W(0)(S7)I (7c), red, 0.19 g (36.3%) room temperature and then worked up by Cp*,W2(0),(//-S)2 (8c), red, 0.12 g (32.8%) column chromatography on silica. Dark-red Cp*2W2(S)(Ö)(//-S)2 (8d), red, 0.10 g (26.8%) Cp*2Mo2(NO)2(//-S)2 (5a) was isolated in 79.3% Both 8 c and 8d were isolated as fine red crystals yield (0.26 g), m.p. 164 °C. which did not melt up to 250 °C. In order to keep the unpleasant smell at a mini­ 3. With H2Se under argon: H2Se was slowly gen­ mum, H2Se was generated by adding a small erated by dropwise addition of H20 (0.22 ml, 1.2 amount of water (0.22 ml, 12 mmol) to a stirred mmol) to a THF suspension (80 ml) containing suspension containing 0.58 g (2 mmol) Al2Se3 in 0.29 g (1 mmol) Al2Se3 and 0.60 g (1 mmol) addition to 0.52 g (1 mmol) Cp*Mo(NO)I2. The Cp*W(NO)I2. In the course of 24 h the stirred mixture was stirred for 24 h and then filtered. The reaction mixture changed the colour from green dark-red solution was concentrated and chroma­ over red and dark-red to black. Filtration and tographed on silica. Elution with CH2Cl2/pentane evaporation of the solvent THF under vacuum gave two bands, first a dark-green zone containing gave a black residue which was separated into Cp*2Mo2Se4 (6) (0.09 g, 22.8%) and second a three compounds by chromatography: Elution by Product Colour Yield CH2Cl2/pentane (1:2) Cp*W(NO)(Se5) (3b) violet 0.16 g (21.3%) CH,Cl-,/pentane (1:1) Cp*,W2(0)?(/z-Se), (9c) red 0.20 g (48.2%) CH,Cl2/pentane (1:2) Cp*;w;(0)(Se)(//-Se), (9d) black 0.10 g (22.4%) The binuclear complexes 9c and 9d do not melt up to 250 °C. 1496 M. Herberhold et al. • Halfsandwich Nitrosylmetal Complexes c) Preparation of Cp* W-oxo complexes 4/m or 4/mmm Laue symmetry, and the systematic The Cp*W compounds containing terminal sul- absences in the diffraction data established the fido or selenido ligands are quantitatively convert­ space group as either P4,2,2 or P 4 3 2 ,2 . The Ro­ ed into the corresponding compounds containing ger’s test and the chemically sensible results of re­ terminal oxo ligands if stirred in solution (CH2C12, finement showed that P432,2 is the correct space THF) in the presence of air, e.g. group for 4a and P4,2,2 for 5b. An empirical ab­ sorption correction was applied to the data sets Cp*W(S)(S7)I (7 a) gives (216 y/-scan reflections, pseudoellipsoid model). Cp*W(0)(S2)I (7c) rapidly; The structures were solved by direct methods Cp* 2W2(S)2(0 -S)2 (8 a) gives Cp* 2W2(0)(S)(//-S) 2 (8 d) and which located the two metal and the four chalco­ Cp* 2W2(0)2(/*-S ) 2 (8 c) slowly; gen atoms. The remaining non-hydrogen atoms Cp* 2W2(0)(Se)(//-Se) 2 (9d) gives were located through subsequent Fourier and least Cp* 2W2(0)2(/i-Se)2 (9c) squares syntheses. All hydrogens were included as idealized isotropic contributions (d(CH) = d) X-ray structure determination of 0.960 Ä, U = 1.2 U for attached C). All non-hy­ Cp*2Cr?(NO)2(p-S2)2(4a)and drogen atoms were refined with anisotropic ther­ Cp*2Mo2(N O )2(p-Se2) 2 (5b) mal parameters. Tables VI and VII contain the The crystal, data collection and refinement pa­ atomic coordinates and equivalent isotropic ther­ rameters for both 4 a and 5 b are given in Table V. mal parameters for 4 a and 5 b, repectively. The data collection was similar in both cases: A All computer programs and the sources of the black crystal was mounted on a glass fiber with scattering factors are to be found in the epoxy cement, and the unit cell parameters were SHELXTL program library (5.1) (G. Sheldrick, deduced from the least squares fit of 25 reflections Nicolet Corp., Madison, Wisconsin, LT.S.A.). (20° <2.9 <25°). In both cases of 4a and 5b, the Tables of the complete bond distances and bond preliminary photographic data indicated either angles, anisotropic thermal parameters, positional

Table V. Crystallographic data for Formula C2oH 30Cr2N20 2S4 20 30 2 2 2 4 C H Mo N O Se Cp* 2Cr2(NO)2(jU-S2)2 (4a) and Formula weight 562.73 838.19 Cp* 2Mo 2(NO)2(/z-Se2)2 (5b). Crystal system tetragonal tetragonal Space group P432,2 (No 96) P4,2j2 (No 92) Unit cell dimensions a [A] 9.1360(18) 9.345(3) C[kl 29.440(5) 29.787(6) V[A3] 2457.3(8) 2601.7(9) Z 4 4 Crystal dimensions 0.34x0.30x0.40 0.18x0.22x0.40 Crystal colour black black D(calc) [g-cm-3] 1.520 2.140 /i(MoKQ) [cm-1] 1 2 . 1 0 69.78 Temp. [K] 296 296 Transm. [T(max.)/T(min.)] 1.2 1 1.574 MoK MoK (/ = 0.71073) 20-Scan range [°] 4-58 4-48 Data collected ( h, k, I) + 13, +13, +41 + 11, +11, +35 Reflns. collected 2016 1365 Independent reflns. 1982 1126 Indept observed reflns. 1623 946 Fo >/7ct(F0) (« = 5) (« = 5) Standard/reflns. 3 std/197 reflns. 3 std/197 reflns. Variation in standards < 1 < 1 *(F) [%] 3.74 4.67 Ä(wF) [%] 4.14 4.35 A/o (max.) 0.004 0.006 4 Ke) [e-Ä-3] 0.31 0.844 N0/Nv 11.93 7.0 GOF 1.105 1.108 M. Herberhold et al. ■ Halfsandwich Nitrosylmetal Complexes 1497

Table VI. Atomic coordinates (* 104) and isotropic ther­ Table VII. Atomic coordinates (x 104) and isotropic mal parameters (Ä2* 103) for Cp*2Cr2(NO)2(//-S2)2 (4a). thermal parameters (Ä2* 103) for Cp*2Mo2(NO)2(//-Se2)2 (5 b). Atom X y z U* Atom X y z U* Cr 8750.7(7) 1013.3(7) 5303.9(2) 25.7(2) S (l) 8567(1) 1987(1) 4560(1) 37(1) Se(l) 2058.1(19) -1586.2(22) - 491.9(6) 40.1(6) S(2) 8579(1) - 214(1) 4589(1) 34(1) Se(2) -1617.8(20) - 413.8(19) 475.2(5) 37.6(6) O 11538(4) 2229(4) 5529(1) 47(1) Mo 971.4(15) -1372.0(14) 296.3(4) 29.0(4) N 10418(4) 1723(4) 5402(1) 30(1) N 1645(15) 351(14) 411(4) 33(5) C (l) 6274(5) 1165(6) 5398(1) 42(1) O 2180(14) 1478(15) 550(4) 58(5) C(2) 6927(5) 2545(6) 5485(2) 43(2) C(l) 990(21) -2324(16) 1016(5) 37(6) C(3) 7878(5) 2400(5) 5857(1) 38(1) C(2) 2440(21) -2282(20) 854(6) 49(7) C(4) 7862(5) 914(5) 5996(1) 37(1) C( 3) 2576(19) -3205(19) 491(6) 45(6) C(5) 6854(5) 153(6) 5719(1) 38(1) C(4) 1224(20) -3885(15) 417(5) 39(6) C(6) 5143(6) 875(7) 5046(2) 71(2) C(5) 263(19) -3377(18) 738(6) 41(6) C(7) 6539(7) 3955(7) 5252(2) 67(2) C(6) 3619(20) -1414(23) 1067(6) 69(8) C(8) 8712(7) 3626(7) 6087(2) 65(2) C(7) 3961(22) -3598(24) 242(6) 80(9) C( 9) 8677(6) 296(7) 6394(1) 58(2) C( 8) 939(27) -5065(17) 78(6) 75(9) C(10) 6364(6) -1407(7) 5767(2) 63(2) C(9) -1233(20) -3847(19) 809(7) 64(8) C(10) 434(22) -1559(21) 1404(5) 61(8) * Equivalent isotropic U defined as one third of the trace of the orthogonalized U;j tensor. * Equivalent isotropic U defined as one third of the trace of the orthogonalized tensor.

parameters of the hydrogen atoms, and the lists of Support of our research by the Deutsche For­ the observed and calculated structure factors schungsgemeinschaft and the Fonds der Chemi­ may be obtained from Fachinformationszentrum schen Industrie is gratefully acknowledged. We Karlsruhe, Gesellschaft für wissenschaftlich- thank particularly Dr. W. Milius, Bayreuth, for technische Information mbH, D-76344 Eggen- valuable discussions. G.-X. Jin is grateful for a stein-Leopoldshafen, by quoting the registry num­ postdoctoral fellowship of the Alexander von ber CSD 57 629, the names of the authors and the Humboldt Foundation. journal citation.

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