CRYSTAL AND MOLECULAR-STRUCTURE OF CO6S8(PBU3N)(6) AND SYNERGISM IN THE CLUSTER CORE M6E8P6 (E = S, SE, TE)

Hexanuclear cobalt-sulfur cluster complex Co6S8(PBu3n)(6) is a new mem ber of a series of cage-like homonuclear clusters with skeleton [M6E8P 6](n), in which M=Cr, Mo, W, Fe; Co; E=S, Se, Te; n=-1, 0, +1, +2, +3. The Co-6 octahedron and the S-8 cubane of the title complex are inter calated to form the cluster core, with the P atoms terminally ligated to Co. The synthetic process and the crystal structure analysis show t hat the formation process can be viewed as the construction of three m ononuclear species Co(PBu3n)(2)S to form a metastable trinuclear ''syn thon'' Co-3(mu(2)-S)(3)(mu(3)-S) (PBu3n)(3), two of which then combine to form the final stable cluster Co6S8(PBu3n)(6). Synergism within a molecule having skeleton M6E8P6 was discussed from the following viewp oints: ease of cluster formation; high stability towards redox reactio n; delocalization of valence electrons; electrons of the reduced state s enter the anti-bonding orbitals; and the idea of metal-based valence electrons.