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tallographically characterized cyclophanes have been prepared as part of this work, and their electrochemical behavior will be reported in due c ~ u r s e . ~ ~ * J ~
Acknowledgment. Financial support was provided by NSF Grants CHE-8018199(R.G.F.) and CHE-7901763 (V.B.). It is a pleasure to acknowledge the receipt of the [2J(1,2,3,5)cyclophane used to prepare 3 from Professor H. Hopf and helpful electrochemical consultation from Professor C. Michael Elliott. R.G.F. is a Dreyfus Teacher-Scholar (1982-1987)and an Alfred P. Sloan Foundation Fellow (1982-1984). Registry No. 1, 71861-31-9; 2,82871-67-8; 3, 82880-39-5; 4, 82871-65-6; (~6-hexamethylbenzene)(q4-hexamethylbenzene)ruthenium, 83927-89-3; (qe-hexamethylbenzene)([ 26](1,2,3,4,5,6)cyclophane)ruthenium, 83927-87-1;($-hexamethylbenzene)( [24](1,2,3,5)cyclophane)ruthenium,83927-88-2;($-hexa(1,2,4,5)cyclophane)ruthenium, 83927-90-6. methylbenzene)( [24]
Synthesls, Structure, and Properties of [(CHS)~C~I,VS, Stephen A. Koch and Venkatasuryanarayana Chebolu Department of Chemistry State University of New York at Stony Brook Stony Brook, New York 11794 Received September 8, 1982
Summary: The preferred metallo polysulfide chelate ring size in [(CH3)5C5]2VS2(1) is dramatically attered from that in the previously reported [C,H,] ,VS5 (2).
The metallo polysulfide chelate ring size of [C5H5],MS, compounds of the early transition elements is strongly metal dependent. In the case of Ti,l Zr,, Hf,2and V,334the MS5 ring is the exclusive product while for Mo5 and W6 the MS4 ring is the most stable.' We wish to report that substitution of the cyclopentadienyl rings by pentamethylcyclopentadienyl groups dramatically alters the ring size preference from CpzVS5(2) to [(CH3)5CS]2VS2 (1). The chemistry of polychalcogenide ligands, particularly S2" and Se2,-, is of considerable interest both for homogenous metal complexes and in solid-state materials.s Decamethylvanadocene (3) is transformed quantitatively (4) by reaction with PC13 in diethyl to [(CH3)5C5]2VC12 ether.9 The reaction of a solution of 4 in acetone with aqueous (NH4)&3, for 2 h at 60 OC, followed by hot filtration, produces black crystals of l in 50% yield. These (1)Kopf, H.; Kahl, W. J . Organomet. Chem. 1974, 64, C37. (2) McCall, J. M.; Shaver, A. J. Organomet. C h e m 1980, 193, C37. (3) Kopf, H.; Wirl, A.; Kahl, W. Angew. Chem., Int. Ed. Engl. 1971, 10, 137. (4) Muller, E. G.; Petersen, J. L.; Dahl, L. F. J . Organomet. Chem.
1976, 111,91. (5) Block, H. D.; Allmann, R. Cryst. Struct. Commun. 1975, 4, 53. (6) Davis, B. R.; Bernal, I. J . Cryst. Mol. Struct. 1972, 2, 135. (7) (C5H5)2M~S2 has been reported, but it readily converts into the more stable (C5H5)2M~Sl:Kopf, H.; Hazari, S. K. S.; Leitner, M. Z. Naturforsch., B: Anorg. Chem., O g . Chem. 1978, 33B, 1398. (8) Muller, A.; Jaegermann, W. Inorg. Chem. 1979,18,2631. Rakowski Dubois, M.; Dubois, D. L.; VanDerveer, M. C.; Haltiwanger, R. C. Ibid. 1981, 20, 3064 Seyferth, D.; Henderson, R. S.; Song, L.-C. Organometallics 1982, 1, 125. Bolinger, C. M.; Hoots, J. E.; Rauchfuss, T. B. Ibid. 1982,1,223. Hoffmann, R.; Shaik, S.; Scott, J. C.; Whangbo, M.-H., Foshee, M. J. J. Solid State Chem. 1980,34,263. Rouxel, J. Mol. Cryst. Lip. Cryst. 1982, 81,31. (9) M o r h , M. Transition M e t . Chem. (Weinheim, G e r . ) 1981, 6, 42.
Figure 1. Ortep diagrams of 1. Selected distances (A) and angles (deg) for 1; corresponding parameters for 2 are given in the square V-C, = 2.349 (6)[2.300];S-S' brackets: V-S = 2.390(1)[2.457]; = 2.053(3);V-(CH,)& = 2.023 [1.959]; S-V-S' = 50.86 (8)[89.3 (l)];((CH3),C,)-V-((CH,),C,) = 140.2 [134.1].
reaction conditions are similar to those used to prepare [C5H5l2VS5(2).3 Alternately 1 can be prepared by the reaction of 4 with Na2S2. An X-ray diffraction study of 1 has revealed that the molecule crystallizes in the orthorhombic space group Fdd2 with a = 17.514 (4)A, b = 26.221 (4)A, c = 8.661 (4)A, V = 3973 (4)A3, and Z = 8. Diffraction data was collected on an Enraf-Nonius diffractometer using Mo K a radiation. The structure was solved by using Patterson and difference Fourier methods. Final least-squares refinement of all the non-hydrogen atoms gave R = 0.047and R, = 0.064 using 1369 unique reflections with I > 3 4 0 . The molecule (Figure 1) possesses a crystallographically imposed C2axis which passes through the vanadium atom and the midpoint of the S-S bond. The S-S distance of 2.053 (3)A is typical for a coordinated disulfide;8 compound 1 is best formulated as V4+(S22-).Important bond distances and angles of 1 are compared with those of 2 in Figure 1. The change in the size of the VS, ring going from 2 to 1 is likely dominated by steric considerations.1° The smaller VS2 ring lessens sulfur-methyl steric interactions. The recent report of the structure of [ (CH3),C5I2TiS3 provides another example of the stability of smaller rings in the (CH3)5C5series of compounds.l' In both the [C5H512MS,and the [(CH3)5C5]2MSn series, a decrease in MS, ring size correlates with an increase in the number of d electrons.12 The decrease in the X-M-X angle in [C5H512MX2compounds as a function of increasing d electron count is well documented and well ~nderstood.'~J~ Smaller X-M-X angles should favor smaller MS, rings. Compound 1 gives a characteristic sharp intense IR band at 552 cm-' that is assigned to the S-S stretch. The small vanadium hyperfine splitting value (45 G) in the ESR spectrum of 1 is also distinctive. The hyperfine coupling constant for 4 (75 G) is close to the value found for [C5H5]2VC12,'3 which is a typical value (60-75 G) for [C5H5I2VX2 compounds including 2.4 The reduced splitting constant for 1 is nearly identical with those reported for [C5H5I2VLwhere L is a ' 7 l i g a n d s u c h as an a l k e n e or a1k~ne.l~ (10) The steric interactions among the ligands is reflected in the disDlacements of the methvl ProuDs from the least sauares Dlane of the cyclopentadienyl rings: C"6 (6.138A), C7 (0.250 A), Cs'(0.021 h),C9 (0.390 A). C10 (0.266 A). '(11)Bird, P. H.;McCall, J. M.; Shaver, A.; Siriwardane, U. Angew. Chem., Int. Ed.Engl. 1982, 21, 384. (12) (a) C5HSseries: do [C5H5I2MS5,M = Ti,' Zr,lzbHflzb(S-Ti-S = 95.0 (1)"); d' [CbHJZVS6 (S-V-S = 89.3 (1)'); d2 [C5H5]2MSi (S-M-S (M = Mo) = 88.2 (2)', (M = W) = 89.1 (l)'),5,6 [ C ~ H ~ I ~ M O S(CHJ5C5 Z.'~~ series: do [(CH3)5C5]zTiS311 (S-Ti-S = 84.44 (9)'); d' 1 (S-V-S = 50.86 (8)"). (b) No crystallographic information. (13) Petersen, J. L.; Dahl, L. F. J . A m . Chem. SOC.1975, 97, 6422. (14) Lauher, J. W.; Hoffmann, R. J . Am. Chem. SOC.1976,98, 1729.
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Organometallics 1983, 2, 351-352
The electrochemistryof 1shows a reversible one-electron oxidation a t 0.19 V (vs. SCE) and two irreversible reductions a t -0.84 and -1.49 Val6 Refluxing a solution of 1 in acetonitrile in the presence of added sulfur results in its transformation into [ (CH3)6CS]2V2S5.17J8Further reactivity studies of the coordinated S2are in progress.
Acknowledgment. Partial financial support was provided by a Dow Chemical U.S.A. Grant of Research Corp. Registry No. 1, 84174-74-3;2, 11077-28-4;3, 74507-60-1; 4, 83617-50-9. Supplementary Material Available: Tables of crystallographic data, positional and thermal parameters, least-squares planes, and bond distances and angles and a listing of structure factor amplitudes (11pages). Ordering information is given on any current masthead page. (15) Petersen, J. L.; Griffith, L. Inorg. Chem. 1980, 19, 1852. (16) DC polarography, DMF solvent, 0.1 M Et,BF, supporting electrolyte, platinum electrode. The slope.of the plot of log (id - i)/i)) vs. E 57 mV [0/1+],89 mV [0/1-],95 mV [I-/2-1. (17) 'H NMR (CDClJ 6 2.17 ( 8 ) ; mass spectrum, m / e (relative intensity) 532 (20, M+), 500 (40, (M - S)+),468 (100,(M - 2S)+). (18)(C5H&V2S5has been reported: ref 4. Schunn, R. A.; Fritchie, C. J.; Prewitt, C. T. Znorg. Chem. 1966,5,892. Bolinger, C. M.; Rauchfuss, T. B.; Rheingold, A. L. Organometallics 1982, 1, 1551.
Chemlstry of Slloles. 1-Methyldlbenzosllacyclopentadlenlde Anlon Mltsuo Ishlkawa, ' I Tatsuru Tabohashl," Hakubun Ohashl,le Makoto Kumada,* l a and Jun Iyodatb Department of Synthetic Chemistry, Faculty of Engineering Kyoto University, Kyoto 606, Japan Government Industrial Research Institute Osaka Ikeda, Osaka 563, Japan Received September 8, 1982
Summary: The reaction of 1-methyl-1-(trimethylsily1)dibenzosilole with (methyldiphenylsilyl)lithiumin THF afforded the 1-methyldibenzosilacyclopentadienide anion in high yield. Similar reaction of l-methyl-3,4-diphenyl-l,2,5tris(trimethylsilyl)silolewith (methyldiphenylsilyl)lithium gave a lithium compound as the sole product, which formed two isomers of l-methyl-3,4-diphenyI-2,2,5-tris(trimethylsilyl)-1-(methyldiphenylsily1)-1-silacyclopent-3-ene in high yield on hydrolysis.
The silacyclopentadienide anion is an attractive compound for theoreticians as well as silicon chemists. However, all attampts to prepare this species have been unsuccessful to date. In this paper we report the successful synthesis of the anion of dibenzosilole and its behavior. Recently, we found that the reaction of 1-methyl-1-(trimethylsily1)dibenzosilole (1) with an excess of an alkyllithium such as methyl- or butyllithium afforded the corresponding 1,l-dialkyldibenzosilolein almost quantitative yield.2 In marked contrast, the reaction with a silyllithium has been found to produce the l-methydibenzosilacyclopentadienide anion (2). The 'H NMR (1) (a) Department of Synthetic Chemistry. (b) Government Industrial Research Institute Osaka. (2) Ishikawa, M.; Nishimura, N.; Sugisawa, H.; Kumada, M. J.Organomet. Chem. 1981,218, C21.
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spectrum of anion 2 revealed a sharp resonance at 6 0.24, due to methylsilyl protons. The UV spectrum of 2 in THF exhibits characteristic absorptions at 377 ( 6 5700) and 546 nm (1200), while dibenzosilole 1 shows absorptions at 234 ( 6 25000), 242 (24000), 278 (14000), 288 (13000), 304 (1700), and 318 nm (170). In a typical experiment, 3.0 mL of (methyldiphenylsilyl)lithium, prepared from 0.9546 g (2.42 mmol) of 1,2dimethyltetraphenyldisilane in 10 mL of THF, was added to 0.3466 g (1.29 mmol) of 1 in 2 mL of T H F a t -78 "C under a dry argon atmosphere. The mixture was warmed to room temperature and hydrolyzed with dilute hydrochloric acid. The organic layer was separated, washed with water, and dried over potassium carbonate. GC analysis of the resulting solution using nonadecane as an internal standard showed the presence of l-hydro-l-methyldibenzosilole3 (3) and siloxane4 (4) in 23 and 46% yield, respectively, in addition to a 65% yield of 1,1,1,2-tetramethyldiphenyldisilane (5). Compounds 3 and 4 were isolated by preparative GC analysis. That siloxane 4 is a secondary product was shown by the fact that compound 3 could readily be transformed into 4 under the conditions used. The formation of 3 clearly indicates that the silicon-silicon bond in dibenzosilole 1 was cleaved by the silyllithium reagent t o give t h e dibenzosilacyclopentadienide anion 2. The reaction of 1 with 1 equiv of (methyldiphenylsily1)lithium in THF a t -78 "C, followed by treatment of the solution with ethyldimethylchlorosilane at room temperature, gave tetramethyldiphenyldisilane 5 and 1(ethyldimethylsily1)-1-methyldibenzo~ilole~ (6) in 68 and 64% yield, respectively, as shown in Scheme I. Interestingly, in this reaction, no l-ethyl-1,1,2-trimethyldiphenyldisilane, which might be expected to form from (methyldiphenylsily1)lithium and ethyldimethylchlorosilane, was detected by either spectroscopic or GC analysis, indicating that the equilibrium lies far to the formation of anion 2. l-Methyl-3,4-dipheny1-1,2,5-tris(trimethylsilyl)silole6 (7) reacts with (methyldiphenylsily1)lithium in a manner different from dibenzosilole 1. Thus, treatment of 0.2303 g (0.50 mmol) of 7 in 6 mL of T H F with 1.7 mL (0.77 mmol) of (methyldiphenylsily1)lithium-THF solution at -78 "C gave a dark green solution. After a 15-h reaction time at room temperature, analysis of the resulting solution by lH NMR showed the presence of anion 8 ['H NMR 6 -0.43 (9 H, s, Me3Si), -0.17 (9 H, s, Me,Si), 0.34 (9 H, s, Me3Si),0.15 (3 H, s, MeSi), 0.85 (3 H, s, MeSi), 6.4-8.0 (20 H, m, ring protons)] as the sole product. After hydrolysis of the mixture with dilute hydrochloric acid, the organic layer was separated and the solvent was evaporated. The residue was chromatographed to give white crystals (82% yield). The lH NMR spectrum of the crystals that were gas chromatographically homogeneous showed the presence of the two isomers of l-methyl-3,4-dipheny1-2,2,5tris(trimethylsily1)- 1- (methyldiphenylsily1)-l-silacyclo-
(3) Compound 3: 'H NMR 6 0.57 (3 H, d, J = 4 Hz, MeSi), 4.92 (1 H, q, J = 4 Hz, HSi), 7.2-7.9 (8 H, m, ring protons);IR 2125 cm-'; exact mass
calcd for CI3Hl2Si196.0708, found 196.0713. (4) Compound 4: 'H NMR 6 0.36 (6 H, s, MeSi), 7.C-7.7 (16 H, m, ring protons); IR 1076 cm-'; mass spectrum, m / e 406 (M+). Anal. Calcd for C,,H22Si20: C, 76.80; H, 5.45. Found C, 76.70; H, 5.34. (5) Compound 6: 'H NMR 6 0.04 (6 H, a, Me2SiEt),0.48 (3 H, s, MeSi), 0.52-0.68 (2 H, m, CH2Si),0.68-1.00 (3 H, m, CH3C), 7.1-7.8 (8 H, m, ring protons); mass spectrum, m / e 344 (M+). Anal. Calcd for C17H&i: C, 72.27; H, 7.85. Found: C, 72.46; H, 8.07. (6) Ishikawa, M.; Sugisawa, H.; Harata, 0.;Kumada, M. J. Organomet. Chem. 1981, 217, 43.
0 1983 American Chemical Society
