Organometallics 1995, 14, 2277-2287
2277
Reactions of Di- and Polynuclear Complexes. 142 Synthesis of Permethylated-Cyclopentadienyl Chalcogeno-Bridged Compounds: A Route to the Stable Thiolatosulfidocarbonyldimolybdenum(II1)Complex [Cp*2Mo2(C0)20c-SMe)2(/1-S)]. Crystal Structure Determination of [C~*~MO~(CO)~(C~-SM~)~C~-SH)] [BF41 Philippe Schollhammer, FranCois Y. Pbtillon,* Roger Pichon, Sylvie Poder-Guillou, and Jean Talarmin URA CNRS 322 “Chimie, Electrochimie MolCculaires et Chimie Analytique”, Facultt des Sciences, UniversitC de Bretagne Occidentule, B.P. 809,29285 Brest-Cedex, France
Kenneth W. Muir* and Ljubica Manojlovitr-Muir Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, Great Britain Received October 21, 1994@
The new diamagnetic carbonyl-containing sulfido complex [Cp*zMoz(CO)z@-SMe)z@-S)I (8)has been obtained by the thermal reaction of the pentamethylcyclopentadienyl compound [Cp*2Moz(CO)41(1)with MeSSMe; the other predominant product of the reaction, [Cp*zMoz(C0)4@-SMe)~l(3), results from the oxidative addition of dimethyl disulfide across the Moz center. Monitoring this thermal reaction by IR spectroscopy indicated that 8 arises from decarbonylative dimerization of [Cp*Mo(C0)3(SMe)l(2). Reactions with other dialkyl and diary1 chalcogenides, REER (ER = SPh, SeMe), and with thiol (HSBz) and selenol (HSePh) led only to the formation of tetracarbonyl chalcogenato-bridged derivatives [Cp*zMoz(CO)4 @-ER)21 (ER = SPh (4), SBz (S), SeMe (61, SePh (7)). A thermolysis study showed the degradation of 3 to [Cp*2Moz@-SMe)4](12)via [Cp*zMoz(C0)2@-SMe)~] (9); 8 was decarbonylated directly to 12. Investigation of the reaction between 8 and electrophilic reagents showed that dinuclear molybdenum(II1) complexes [Cpz*MoZ(CO)z@-SMe)z@-SH)IXE= BF4 (16),C1(17),F(l8)l were formed stereospecifically as the cis isomers. 16 has been structurally characterized by X-ray diffraction. Crystals of 16 are orthorhombic, space group Pcab, a = 15.655(5) b = 16.173(3) c = 23.6626) and 2 = 8. The complex cation has approximate CzUsymmetry and the Mo-Mo bond length is 2.772(2) Complex 3 was readily oxidized (21). All new by Ag[BF41 to yield the dicationic product [C~*~MOZ(CO)~@-SM~)~I[BF~IZ thiolato-bridged complexes have been characterized by spectroscopic analyses.
A,
A,
A,
Introduction The continuing interest in sulfur-containing transition metal complexes reflects their importance in biology and catalysis.2 Dinuclear thiolato-bridged complexes, in particular those of molybdenum, have been widely ~ t u d i e d , ~since - ~ they have found applications both as synthons for the production of heteronuclear clusters4 and as models of sulfur-metal sites in biological or catalytic systems. We have focused on p-thiolato cyclopentadienyl (Cp) c~mplexes,~ particularly on their electrochemistry and on their ability t o electrogenerate reactive sites6. Group 6 metal carbonyl compounds, such as [CpM(C0)31~,[CpM(CO)zIz, or [CpM(CO)&l (M = Cr, Mo, W, Abstract published in Advance ACS Abstracts, April 15,1995. (1) Schollhammer, P.; PBtillon, F. Y.; Pichon, R.; Poder-Guillou, S.; Talarmin, J.;Muir, K. W.; Girdwood, S. E. J. Organomet. Chem. 1995, 486,183. (2)(a) Wachter, J.J. Coord. Chem. 1987,15,219.(b) Stiefel, E. I. Prog. Znorg. Chem. 1977,22,1. (c) Holm, R. H. Chem. SOC.Rev. 1981, (e)Rakowski 10,455.(d) Coucouvanis, D. ACC.Chem. Res. 1991,24,1. Dubois, M. Chem. Rev. 1989,89,1. (0Curtis, M. D. Appl. Organomet. Chem. 1992,6,429. (g) Wiegand, B. C.; Friend, C. M. Chem. Rev. 1992, 92,491. @
A.
X = H, Cl), are known to react with REER or REH (E = S, Se, Te), and under vigorous conditions the non(3)(a) Poli, R. J.Coord. Chem. 1993,29,121.(b) Deavenport, J. L.; Stubbs, R. T.; Powell, G. L.; Sappenfield, E. L.; Mullica, D. F. Znorg. Chim. Acta 1994,215,191.(c) Hughes, D. L.; Lane, J. D.; Richards, R. L.; Shortman, C. J. Chem. SOC.,Dalton Trans. 1994,621.(d) Shin,J. H.; Parkin, G. Polyhedron 1994,13, 1489.(e) Adams, H.; Bailey, N. A,; Brisson, A. P.; Morris, M. J. J. Organomet. Chem. 1993,444,C34. (0Matsuzaka, H.; Hirayama, Y.; Nishio, M.; Mizobe, Y.; Hidai, M. Organometallics 1993, 12, 36. (g) Chojnacki, S. S.; Hsiao, Y. M.; Darensbourg, M. Y.; Reibenspies, J. H. Znorg. Chem. 1993,32,3573. (h) Green, M. L. H.; Ng, D. K. P. J. Chem. SOC.,Dalton Trans. 1993, 11.(i)Kuhn, N.; Zauder, E.; Boese, R.; Blaser, D. J. Chem. SOC.,Dalton Trans. 1988,2171. (4) (a) Curtis, M. D.; Williams, P. D.; Butler, W. M. Znorg. Chem. 1988,27,2853.(b) Li, P.; Curtis, M. D. Inorg. Chem.1990,29, 1242.
(c) Robin, F.; Rumin, R.; Petillon, F. Y.; Folley, K.; Muir, K W. J. Organomet. Chem. 1991,418, C33. (d) Eremenko, I. L.; Berke, H.; Kolobkov, B. I.; Novotortsev, V. M. Organometallics 1994,13,244. (5)(a) Guerchais, J.E.; Le QuBrB, J. L.; PBtillon, F. Y.; ManojloviCMuir, Lj.; Muir, K. W.; Sharp, D. W. A. J. Chem. SOC.,Dalton Trans. 1982,283. (b) Gomes de Lima, M. B.; Guerchais, J. E.; Mercier, R.; PBtillon, F. Y. Organometallics 1986, 5, 1952. (c) PBtillon, F. Y.; Schollhammer, P.; Talarmin, J. J. Organomet. Chem. 1991,411,159. (6)(a)Courtot-Coupez, J.;GuBguen, M.; Guerchais, J. E.; PBtillon, F. Y.; Talarmin, J.; Mercier, R. J. Organomet. Chem. 1986,312,81. (b) GuBguen, M.; PBtillon, F. Y; Talarmin, J. Organometallics 1989,8, 148. (c) El Khalifa, M.; Gueguen, M.; Mercier, R.; PBtillon, F. Y.; Saillard, J. Y.; Talarmin, J. Organometallics 1989,8,140. (d)Gloaguen, F.; Le Floc’h, C.; PBtillon, F. Y.; Talarmin, J.; El Khalifa, M.; Saillard, J. Y. Organometallics 1991,10, 2004.
0276-733319512314-2277$09.00/0 0 1995 American Chemical Society
2278 Organometallics, Vol. 14,No. 5, 1995
carbonyl complexes [CpM(ER),12 [x = 1.5 (Cr) or 2 (Mo, W)] are isolated.' It has been shown that dimeric intermediates, [CpM(CO),(ER)]2, are involved in these reactions though only those with x = 1 and 2 have so far been characterized."'i8 It is also established that the ease of carbonyl loss from the mononuclear species [CpM(C0)3ER]depends on E, R, and M as well as on the severity of the conditions;8i-mAbrahamson et a1.8k consider that the o-inductive effect of ER is critical: carbonyl is lost more easily if ER is electron-rich. If this view is correct, replacement of Cp by the more electronrich pentamethylcyclopentadienyl (Cp*) should influence the ease and possibly the course of decarbonylation reactions. Accordingly, we describe here the decarbonylation reaction of the pentamethylcyclopentadienyl complex [Cp*Mo(CO)zlz(1)in the presence of dialkyl and diaryl sulfides and selenides, thiols, or selenols. The results permit the effect of replacing Cp by Cp* to be assessed: reactions of CpMo-carbonyl complexes with RSSR, RSH, RSeSeR, and RSeH have been thoroughly studied7,8whereas the reactions of analogous Cp*-carbonyl complexes with chalcogenide compounds have not previously been reported.
Results and Discussion 1. Synthetic Studies and Spectroscopic Characterization. A red solution of [Cp*zMoz(COM (1) in toluene reacted with MezSz a t 80 "C within 2 h to give a yellow-brown solution from which were isolated two main products: [Cp*2Moz(CO)&-SMe)2 @-SI1(8)in 35% yield and [Cp*2Moz(C0)4@-SMe)21(3)in 40% yield. The reaction gave also significant amounts of four side p r o d u ~ t s ~ (Scheme J ~ - ~ ~ 1). No reaction between 1 and dimethyl disulfide was observed at ambient temperature. Thermal or photochemical treatment of complex 1 with REER (ER = SPh, SeMe) or REH (ER = SBz, (7) (a) King, R. B. J.Am. Chem. SOC.1963,85, 1587. (b) Tillay, E. W.; Schermer, E. D.; Baddley, H. Inorg. Chem. 1968, 7, 1925. (c) 1970, 92, 7470. (d) Connelly, N. G.; Dahl, L. F. J. Am. Chem. SOC. Rakoczy, H.; Schollenberger, M.; Nuber, B.; Ziegler, M. L. J. Organomet. Chem. 1994,467,217. (8) (a) Treichel, P. M.; Morris, J. H.; Stone, F. G. A. J. Chem. Soc. 1963,720. (b) Havlin, R.; Knox, G. R. 2.Naturforsch. B 1966,21,1108. (c)Ehrl, W.; Vahrenkamp, H. Chem. Ber. 1972,105,1471.(d) Davidson, J. L.; Sharp, D. W. A. J. Chem. Soc., Dalton Trans. 1972, 107. (e) Watkins, D. D., Jr.; George, T. A. J. Organomet. Chem. 1975,102,71. (0Petillon, F. Y.; Le QuW, J. L.; Roue, J.;Guerchais, J. E.; Sharp, D. W. A. J. Organomet. Chem. 1980,204, 207. (g) Benson, I. B.; Killops, S. D.; Knox, S. A. R.; Welch, A. J. J . Chem. Soc., Chem. Commun. 1980, 1137. (h) Jaitner, P. J. Organomet. Chem. 1982,233, 333. (i) Jaitner, P.; Wohlgenannt, W. Inorg. Chim. Acta 1985, 101, L43. (i) Grobe, J.; Haubold, R. 2. Anorg. Allg. Chem. 1985, 522, 159. (k) Weinmann, D. J.; Abrahamson, H. Inorg. Chem.1987,26,2133. (1) Shaver, A.; Lum, B. S.; Bird, P.; Livingstone, E.; Schweitzer, M. Inorg. Chem. 1990,29, 1832. (m) Goh, L. Y.; Tay, M. S.; Mak, T. C . W.; Wang, R. J. Organometallics 1992, 11, 1711. (n) Nefedov, S. E.; Pasynskii, A. A.; Eremenko, I. L.; Papoyan, G. A.; Rubinstein, L. I.; Yanovskii, A. I.; Struchkov, Yu. T. Zh. Neorg. Khim. 1993, 38, 76. (9) Poder-Guillou, S.; Schollhammer, P.; Petillon, F. Y.; Muir, K. W. Unpublished results. (10)Goh, L. Y.; Tay, M. S.; Wei, C. Organometallics 1994,13,1813. (11) Rakowski Dubois, M.; Van Derveer, M. C.; Dubois, D. L.; Haltiwanger, R. C.; Miller, W. K. J.Am. Chem. SOC.1980,102, 7456. (12) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennerd, 0.;Watson, D. G.; Tailor, R. J . Chem. Soc., Dalton Z'rans. 1982, S1. (13) Abrahamson, H. B.; Marxen, H. Organometallics 1993, 12, 2835. (14) (a) Boorman, P. M.; Fait, J. F.; Freeman, G. K. W. Polyhedron 1989, 8, 1762. (b) Burrow, T. E.; Hills, A.; Hughes, D. L.; Lane, J. D.; Lazarowych, N. J.; Maguire, M. J.; Morris, R. H.; Richards, R. L. J. Chem. Soc., Chem. Commun. 1990, 1757. (c) Green, M. L. H.; Mountford, P. Chem. SOC.Rev. 1992, 29.
Schollhammer et al.
SePh) gave the corresponding chalcogenato-bridged molybdenum complexes [ C ~ * ~ M O ~ ( C O ) ~(4-71, (~ER)~I and when ER = SPh [Cp*zMo2(C0)2@-ER)zl(10)was obtained in moderate yield (Scheme 2). In the reaction with benzyl mercaptan a significant amount (10%) of the monomeric complex [Cp*Mo(C0)3SBz](15)was also formed. The new compounds 3-15 have been characterized by various spectroscopicmethods (lH and 13CNMR, and IR), elemental analysis, and mass measurements. The spectroscopic data and assigments (Table 1)will not be further discussed, except where interpretation is not straightforward. The structures proposed for the new compounds are shown in Schemes 1-3. The lH NMR spectrum of 8 exhibits only two peaks, which indicates that this compound has a cis-syn geometry. Elemental analyses and mass data accord with the proposed stoichiometry. We have not been able to obtain crystals of 8 suitable for X-ray analysis; however, a structural analysis of the cationic complex [CP*~MO~(CO)~@-SM~)~@-SH)I[BF~I (16)(see below), which was obtained by reaction of 8 with H[BF41, is consistent with the proposed geometry for 8 (Scheme 1). lH and 13C NMR spectroscopy of 3-7 shows equivalence of the C5Me5 rings and ER groups, which implies that these complexes are cis-syn isomers. Unlike the cyclopentadienyl analogues,6a the trans permethylated isomers were not obtained here. The NMR spectra of 9- 11 show inequivalent C5Me5 groups and equivalent alkyl groups on the bridging S atoms, which is consistent with a truns-syn form. Compounds 13 and 14 have been identified by comparison of their spectroscopic data with those of the analogous cyclopentadienyl complexes [C~(CO)MO@-SM~)~MO(CO)~I~~ and [Cp(CO)Mo~-SMe)~Mo(CO~~@-SMe)Mo(CO~2Cpl,g respectively. The lH NMR spectrum of 14 (Table 1) suggests the presence of a mixture of two inseparable isomers in solution; syn-anti isomerism related to the orientation of the methyl groups on the bridging S atoms could account for the spectral pattern. The IR of 15 [v(CO) (cm-l) 2015 (s) and 1930 (s)] is indicative of a mononuclear geometry.8jskJ0 The presence in the 'H NMR spectrum of 15 of two sets of singlets of different intensities attributable to the C5Me5 rings and to the CHzC6Hs protons (Table 1)suggests the existence of two isomers due to a different orientation of the benzyl group relative to the CO plane.15 2. Possible Mechanisms of Formation of Products. As described above, the thermal or photochemical reactions of [Cp*~Mo~(C0)41 (1)with dialkyl or diaryldichalcogenidesREER or with thiol or selenol HER have yielded several complexes depending on the nature of E and R. Scheme 3 presents a possible sequence of reactions ensuing from addition of 2 equiv of REER or HER to 1. First, it should be noted that the p-sulfido complex 8 is only obtained when ER = SMe and that the main products of the oxidation of 1 with dimethyl disulfide are 8 [Mo(III)Iand 3 [Mo(II)I. Decarbonylation of 3 by heating it in either tetrahydrofuran (66 "C) or toluene solution (110 "C) gave the dinuclear product 9 in low ( ~ 3 %and ) good yields (60%), respectively, together with untransformed reactant, but no 8 was formed in these (15)Ashby, M. T.; Enemark, J. H. J. Am. Chem. SOC.1986, 108, 730.
Reactions of Di- and Polynuclear Complexes
Organometallics, Vol. 14, No. 5, 1995 2279 Scheme 1" [Cp*(CO)ZMo= Mo(COhCp*] 1
+
MeSSMe
Me
co
CP*
+
Mo
CP*
8
co co Me
co
3
I + co
CP* 9
Me + cp-
CP*
Me
\ / co
MO -Mo -cp*
\\ Mo and L = Cp > Cp*. Above all, of the mononuclear derivatives may be correlated with they show that the influence of the n-donating effect of the softness of the ER groups so that decarbonylative the Cp* ring is more important than that of ER groups dimerization of [Cp*Mo(C0)3ERl into [Cp*zMoz(COhin these reactions. Thus, replacement of L = Cp by Cp* is (p-ER)2(p-E)],via [Cp*(CO)Mo(LL-SMe)3Mo(CO)Cp*l+, in [LM(C0)3ERlis a major factor governing the decarless likely when ER = SBz, SeMe, or SePh than that it bonylative dimerization reactions of group 6 metal is when ER = SMe. Now, assuming that the mechanism for the formation of [ C ~ * ~ M O ~ ( C O ) ~ ( ~ - E R ) ~ carbonyls. (~-E)I from [Cp*M(C0)3ERl involves initial dealkylation or 3. Reactivity of Sulfido Ligands in [Cp*zMo2dearylation of a p-ER group, we believe that conjugation (CO)&-SMe)2@-S)I (8). The unusual nature of 8 , across the C-S bond when R = Ph makes its rupture particularly the nucleophilic character of the sulfido less likely than when R = Me, thereby rationalizing the ligand suggested that it might be highly reactive, and absence of the SPh analogue of 8. we have therefore investigated its behavior with elecNo Cp analogue of 8 is known and it is possible that trophilic and alkylating agents. Addition of either HX the greater electron release from the Cp* ring stabilizes (X = BF4, C1, F) or [MesOl[BF4] or Me1 to a dichlothis (p-sulfido)dicarbonyldimolybdenum(III)compound. romethane solution of 8 rapidly formed a red color. It has been shown that CpCr analogues of 3 and 5, e.g. Following addition of ether, red powders of 16 or 17[CpzCrz(C0)4(LL-SPh)21and [CpzCrz(C0)2(p-SPh)21,were 20 form from the solution a t ambient temperature in the precursor complexes to the carbonyl-free unsaturgood yields. Elemental analysis of 16 and 19 indicated ated sulfido compound [Cp2Cr2(p-SPh)2(p-S)1,8m but no the presence of a monocation with three sulfur atoms per two molybdenum atoms and 16 has been shown by (17) The mechanism shown in eqs 1-4, suggested by one referee X-ray crystallography (see below) to be [Cp*zMoz(CO)zhas been considered: (p-SMe)&-SH)][BF41. The syn disposition of the methyl [Cp*,Mo,(CO),@-S)] + MeNu [Cp*zMo,(CO),@-SMe)l++ Nusubstituents of the equatorial sulfur atoms, which is (1) observed in the solid state (and in 81, is maintained for 16 in solution, as shown by the very small difference of [Cp*~MO,(CO),@-S)1- [Cp"zMo,(CO),@-S)l + 2CO (2) their chemical shifts (Ad = 0.002 ppm; see Table 2). The [Cp*,Mo,(CO),@-S)I + S,Me, [C~*,MO,(CO),@-SM~)~@'-S)~ other compounds (17-20) were formulated as shown (Scheme 4) by comparison of their spectroscopic data (3) (Table 2) with those of 16. [C~*,MO,(CO),@-SM~)~@-S)I [C~*~MO~(CO)~(~-SM~)~(~-SH)~X (16- 18) can be depro[Cp*~Mo2(CO),@-SMe)~@-S)1 + 2CO (4) tonated with bases such as triethylamine to regenerate the sulfido complex 8. Prolonged heating of a suspenAlthough it cannot be completely ruled out, it appears unlikely for the following reason: the Cp analogue of the [Cp*,Mo2(CO)&-S)I intersion of the cationic tris(thio1ato)-bridgedcomplex [Cp*2mediate, observed only at low temperatures,'* decomposes to [Cp~MozM O ~ ( C O ) ~ ( ~ - S(19) M ~ in ) ~refluxing ]I toluene gave quan(C0)eI at room temperature. The decarbonylation reaction shown in eq 2 should be even less favored for the Cp* derivative than for its Cp titatively compound 8. In the same conditions, the counterpart for which this reaction has not been observed. reaction with cyclopentadienyl analogues [Cp2Mo2(CO)2(18) Herberhold, M.; Jellen, W.; Murray, H. H. J. Orgunomet. Chem. (X = C1, Br) led to the insertion of the (pu-SMe)3]X 1984, 270, 65.
-
-
-
Reactions of Di- and Polynuclear Complexes
Organometallics, Vol. 14, No. 5, 1995 2283
Scheme 4"
co
co
Me
\
I
CP* Me
16 ( X = BF,)
s
Me
19 (X = I)
8
20 (X =BF,)
17 (X = CI) 18 (X = F)
"Reagents and conditions: (i) HX (X= BF4, C1, F), in CHZC12; (ii) EtsN, in CHzClz a t room temperature; (iii) [MesOl[BF41, or MeI, in CH2CL a t room temperature; (iv) X = I, in refluxing toluene, 3 days.
Scheme Sa
\\, co
C
CO L = MeCN
(ii)
CP*
/>
