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292ChemInform Abstract The reaction of the sterically hindered thiolate ligands with AgNO3 in the presence of triethylamine as base in acetonitrile affords the title complexes. The variation in the ligand volume influences the degree of association. Thus for the tris-silyl-substituted methylmercaptans the tetrameric (I) and trimeric compounds (II) are obtained, while for the less hindered bissilyl-substituted ligand theoctanuclear complex (III) is isolated. The relatively unhindered trimethylsilylmethylmercaptan yields a polymer (IV), consisting of chains of linked Ag4(SCH2SiMe3)4 cycles, bridged by monocyclic Ag4(SCH2SiMe3)4 groups and weakly interacting methoxy groups. The structures are determined by X-ray analysis. (I) crystallizes in the space group Pbca with Z = 8; (II) in P1, Z=2; (III) in C2/c, Z=4;and (IV) in C2/c, Z=16.

Electrochemistry of M(η 2 -C 60 )(CO) 2 (phen)(dbm) (M = W 1, Mo 2; phen = 1,10-phenanthroline; dbm = dibutyl maleate) shows that the complexes undergo four sequential reduction processes. As with free C 60 , the first three electrons add reversibly (even if the relevant potentials are shifted ca. 0.15 V toward negative values), whereas the fourth reduction features chemical irreversibility. Cyclic voltammetry gives evidence that, as a consequence of the latter process, the metal fragment decomplexes and [C 60 ] 3Ϫ is released. In good agreement with this picture, a qualitative MO approach shows four close LUMOs for the ground state structure of the uncharged complexes. The first three levels are delocalized over C 60 (somewhat extended to the dmb π system), while the fourth one is metalfullerene antibonding (back donation d π → π* C 60 ) and its occupation causes fulleride dissociation. The EPR spectra of the electrogenerated [1] Ϫ and [2] Ϫ monoanions are significantly different from that of [C 60 ] Ϫ and seem suggestive of metal character for these radical species. At present, this result is unexpected in that the unpaired electron in the anions [1] Ϫ and [2] Ϫ should be intuitively centered on the coordinated fullerene.

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In the first neutral bis-fullerene complexes with tungsten(0) and molybdenum(0) [M(h 2 -C 60 ) 2 (CO) 2 (dbcbipy)] [M = W and Mo, dbcbipy = 4,4A-di(butyl carboxyl)-2,2A-bipyridine] synthesized in solution, the metal atom coordination is distorted octahedral with two CO groups and the bipy group of dbcbipy in the equatorial plane and the metal atom binding in an h 2 -fashion to C-C bonds of two C 60 at axial orientation to give a dumbbell shaped molecule.