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other side by a SMo(h5-C5Ha)(CO), ligand. A consequence of the necessity of electron-pair Re( 1)-Re(2) and Re(1)-Mo(3) bonds is that each of the four metal atoms formally attains a noble-gas electronic configuration, in accord with the observed diamagnetism of t j e compound. The Re-Re bond length of 2.985 (1) Cl A is within the Re-Re single-bo$ range, while the Re-Mo bond length of 2.909 (2) A is notFbly but not unexpectedly shorter than ' that of 3.12 A reportedI3 for (OC)SRe-Mo(hj-C5HS)(C0)3. A prominent structural feature is the presence of the metal-coordinated, tetrahedral-like sulfur atom, S(2), linking the Re2Mo Figure 1. Molecular geometry of the (mixed metal)-sulfur cluster cluster to Mo(4) by means of four CT bonds involving all system [RelMo(/iS-CjH5)(CO)s](S)[SM~(hs-CjHj)(C0)3] containing six valence electrons of the sulfur atom. The other both a trimetal- and a tetrametal-coordinated sulfur atom. The structurally characterized organometallic example of a anisotropically refined rhenium, molybdenum, and sulfur atoms are designated as 50 probability thermal ellipsoids. Important similar sulfur atom tetrahedrally coordinated to four distances are Re(l)-Re(2), 2.985 (1); Re(l)-Mo(3), 2.909 (2); metal atoms is [Fe2(CO)~(SMe)12S.' Re(2). . .Mo(3), 3.927 (2); Re(1)-S(l), 2.448 ( 5 ) ; Re(1)-S(2), 2.473 Each of the three metal atoms in the RezMo cluster ( 5 ) ; Re(Z)-S(l), 2.410 ( 5 ) ; Re(2)-S(2), 2.453 (4); Mo(3)-S(l), has a different coordination of ligands (with the metal 2.487 ( 5 ) ; Mo(3)-S(2), 2.523 ( 5 ) ; and Mo(4)-S(2), 2.550 (5) A. atoms in this molecule assumed to occupy distinct The Re(Z)-Re(l)-Mo(3) bond angle is 83.56 (4)". coordination sites). Based on the premise that its cyclopentadienyl ring sterically fills three coordination sites, the localized environment about Mo(3) can be through partial support of the National Science Foundadescribed as eight-coordinated with a configuration not tion and the Wisconsin Alumni Research Forlndation, unlike that found14 about each Mo atom in both the administered through the University Research Comneutral parent [Mo(hS-CjH&SR)& and its cationic 1 mittee. This study was ably assisted by Fraulein G. offspring, The Re( 1) atom is seven-coordinated, which, Fortuna. on the basis of quasiequivalence of its seven ligands Phillip J. Vergamini, Heinrich Vahrenkamp, Lawrence F. Dah]* (uiz., Mo(3), Re(2), S(1), S(2), and the three CO's), Department of Chemistry, Utiiaersity of Wisconsin may be envisioned as a so-called 4:3 distribution of Madisoti, Wisconsin 53706 ligands, l 5 with a resulting idealized fourfold axis Receiwd July 6, 1971 (relating the two metal and two sulfur atoms to one another) approximately coincident with an idealized threefold axis (relating the three carbonyls to one Organometallic Chalcogen Complexes. XXIV. another). The six-coordinated environment of Re( l), Synthesis, Structure, and Bonding of S(1), S(2), and the three carbonyl ligands about the [MO~(~~-C~H~)~S~]+[S~(CH~)~C~~]Containing a Re(2) atom may be simply described as a distorted Triangular Molybdenum(1V) Cluster Cation with octahedron. Doubly and Triply Bridging Sulfur Atoms1 Originally we expected the bridged dimer [Re(CO)4( S M O ( ~ ~ - C ~ H ~ ) ( CtoO )be ~ )formed ]~ along with Me3Sir: SnCl by cleavage of the S-Sn bonds in [Re(C0)4A systematic investigation in our laboratories of the (SSnMe3)lz upon reaction with M O ( ~ ~ - C ~ H ~ ) ( C O ) reactions ~ C ~ . between thio derivatives of trialkyltin and variThis dimer, which may be an intermediate before ous organo(transition metal) halides for the purpose of decarbonylation and condensation into 1, has not yet obtaining certain desired metal cluster complexes has been isolated. We feel that 1 represents an example of led to the isolation and stereochemical characterization the kind of sulfur-bridged metal cluster complex which of the salt [ M O ~ ( ~ ~ - G H ~ ) ~ S ~ ] + [ S ~ ( CBesides H~)~C~~]-. can be prepared by this synthetic method, Extensions representing a new kind of metal-chalcogen cluster sysof this preparative route hopefully should enable one to tem with the unprecedented feature of containing both design metal-sulfur model systems including those of doubly and triply bridging sulfur atoms, the [Mo3(h5biological interest. The results communicated here CaH5)3S4]+cation generates interest from a bonding will be reported in full upon completion of closely viewpoint in its particular mode of nonconformity to the related work in progress. noble-gas configuration for each metal atom. An addiAcknowledgment. We are most appreciative for the tional incentive for our exploration of the unusual strucfinancial support rendered by the National Science Fountural and electronic properties of cyclopentadienyldation (No. GP-4919 and GP-19175X) for this investimolybdenum-sulfur complexes stems from possible biogation. H. V. is pleased to acknowledge the Deutsche chemical implications with respect to the unknown Forschungsgemeinschaft for a travel grant. The use metal-ligand coordinated units in molybdenum-sulfur of the UNIVAC 1108 computer at the University of enzymes. Wisconsin Computing Center was made available [ M O ~ ( ~ ~ - C ~ H ~ ) ~ S ~ ] + [ S ~was ( C Hobtained ~ ) ~ C I ~ ]asone of the products from the reaction of Mo(h5-CsH5)(13) Yu. T. Struchkov, K. N. Anisimov, 0. P. Osipova, N. E.Kolo(CO)&l in 1,2-dimethoxyethane with ~ ~ I ( C H ~ ) ~ ] ~ S .
+
bova, and A. N. Nesmeyanov, Dokl. Akad. Nauk SSSR, 172, 107 (1967). (14) N. G. Connelly and L. F. Dahl, J . Amer. Chem. Soc., 92, 7470
(19701. . -,\ - -
(15) (a) L. F. Dahl and P. W. Sutton, Inorg. Chem., 2, 1067 (1963); (b) C . H. Wei and L. F. Dahl, ibid., 4 , 4 9 3 (1965).
(1) Previous paper in this series: P. J. Vergamini, H. Vahrenkamp, and L. F. Dahl, J . Amer. Chem. SOC.,93, 6326 (1971). (2) Yield >SO% based on S . Anal. Calcd for M o ~ S I C ~ S ~ C I E H Z I : Mo, 34.02; S, 15.16; C, 25.55; H, 2.86. Found: Mo, 35.20; s, 17.54; C, 26.48; H, 2.73; mp, 230" dec.
Communications to the Editor
6328
sulfur atoms as well as by direct Mo-Mo interactions. The cyclopentadienyl ring attached to each molybdenum atom has its corresponding centroid equidistant from the two adjacent doubly bridging sulfur atoms and the one triply bridging sulfur atom. On the basis of assunied cylindrical symmetry for each cyclopentadicnyl ring, thc cation expcrimcntally conforms to a Csp-31ngeonietry. The framework of the entire cation can be visualized as arising from a cubane-like M O $ ( ~ ~ - C ; H : )archi~S~ tecture6 by the formal removal of one Mo(h5-CjHj)-Figure I . Stereochemistry of the [MO~(/~~-C;,H;~)~S,]' cation which group. The resulting [ M O ~ ( ~ ~ - C ~ H : )cation ~ S ~ ] +is ideally conforms t o a C:jL-3mgeometry (based on assumed cyisostructural with the [Mn3(hs-C;HJ3(NO),] moleculeG lindrical sq nimetry for each cyclopentadienyl ring). The aniso(where NO ligands occupy the sulfur positions). The tropically relined molybdenum and sulfur atoms and isotropically same basic geometrical unit can be formally derived refined carhon atoms are shown as 50:< probahility thermal ellipsoi cis, from the P-Nb3X8 type structure (where X = C1, Br, I)' if the three halogen atoms coordinated to each niobium atom of a given Nb3Xl cluster are replaced by a cycloThe diamagnetic character of this air-stable compound pentadienyl ring. was established from a magnetic susceptibility measureThe presence of a formal oxidation state of 4+ for each ment3 and from a proton nmr spectrum which showed in M o (corresponding to a d 2 electronic configuration) in methanol solution only one sharp peak at 6.20 ppm the [Mo3(hj-CjHJ3S4]+cation enables an electron-pair (external TMS as standard) due to the cyclopentadienyl coupling between each pair of Mo(IV). In analogous hydrogens. Recrystallization from CH2C12 solution fashion, there is a great tendency for Mo(V) complexes to gave dark green needle-like plates which an X-ray form dimeric sulfur- or oxygen-bridged species with diffraction analysis showed to belong to the triclinic sysspin pairing of the d 1 electrons of the two Mo(V)'s. tem. Unit cell dimensicns are a = 11.887 (I), b = Definitive evidence for strong electron-pair interactions 12,485 (I), c = 9.526 (1) A , a = 101.642 ( 3 ) , = 97.022 in [ M O ~ ( @ - C ~ HJ+ ; ) ~isS provided ,by its short Mo-Mo ( 3 ) , y = 107.819 (3)". The experimental density (flotadistances of Fverage value 2.812 A which parallel that tion) of 2.2 i 0.1 g ~ m agrees - ~ with a calculated value of 2.894(5) A in the sulfur-bridged [MoO(hj-C5H3)Sl2 of 2.18 g ~ m for - ~2 = 2. The structure was solved dimer for which a direct M o - M o interaction was profrom interpretations of Patterson-Fourier maps composedS between the two Mo(V)'s. In [ M o ~ ( ~ ~ - C ~ H ~ ) ~ puted with data collected with Mo K a radiation on a SA]+the average distance from the dFubly bridging sulGeneral-Electric full-circle diffractometer by the 8-26 fur atoms to the Mo(1V) is 2.z93 A compared to the scan technique. Full-matrix least-squares refinement, similar average value of 2.314 A for the distances from performed under P i symmetry on 2579 absorptionthe triply bridging sulfur atom to the Mo(IV). These corrected data for which IF,) 2 4.0a(F0), yielded an Mo;S bond lengths are also analogous to those of 2.317 RI value of 5.6%. In this refinement, rigid-body con(3) A (average) in [ M O O ( ~ ~ - C ~ H ~but ) S ]are , , ~ considerstraints were applied to each C5Hj ring (uiz., Djl, ably shorter than the Mo-S bond lengths in other comgeometry) and to each CH3 group; the isotropically plexes+ 1 and the estimate$ normal Mo(V)-S singleassigned temperature factors for the hydrogen atoms bond distance of 2.487 (7) A . Considerable A bonding were not varied, while all carbon atoms were refined was propounded8 to exist in the four-membered Mo& isotropically and all other atoms anisotropically. ring bridging system of [MoO(h5-CjH5)SI2to account Crystalline [ M O , ( ~ ~ - C ~ H ~ ) ~ S ~ ] + [ S ~ is ( CcomH ~ ) ~ Cfor I ~ ]the - observed Mo-S bond shortening. The Mo-Sprised of discrete cations and anions. The [Sn(CH3)3- Mo bond angles subtended at the triply bridging sulfur CI2]- anion can be considered as an axially distorted atom range from 74.7 (1) to 74.9 ( l ) O , with an average trigonal-bipyramidal structure of C3,,-3msymmetry with value of 74,8", while those subtended at the doubly the three methyl groups located at equatorial sites and bridging sulfur atoms range from 75.3 (1) to 75.8 (I)", the two chlorine atoms at axial sit$s. The three Sn-CH3 with an average value of75.6". bond length: are all within 0.01 A of the average value In contrast to other molybdenum cyclopentadienyl of 2.12 (1) A, whereas t>e two Sn-C1 bond lengths of complexes, in [ M o ~ ( ~ ~ - C ~ H and ~ ) ~inS[MoO(h5--CjH5).~]+ 2.572 (4) and 2.696 (3) A are distinctly dissimilar, with SIz each M o is deficient by two electrons from attaining the latter value being the longest such bond reported for a so-called closed-shell electronic configuration. Qualia direct Sn-C1 interaction. A detailed discussion of tative M O symmetry argumentsI2 based on CB"symmethe stereochemistry and bonding of the anion will be try indicate that the nine metal symmetry orbital compresented elsewhere. (5) Although to our knowledge Mor(h6-CsH5)rS4has not as yet been The [ M O ~ ( ~ ~ - C ~ Hcation ~ ) ~ S(Figure ~ ] + 1) consists of synthesized, it, as well as the corresponding Cr4(h5-CsHs)rS~tetramer, three Mo(h5-CjHj)moieties positioned at the vertices of prepared by I
