REDUCTIVE ADDITION AT THE W354(4)- A SYNERGETIC REACTION LEADING TO THE HOST-GUEST COMPOUND (ME2NH2)6[(SCN)9W3S4SNCL3].0.5H2O( CORE BY SN2+OR AN UNUSUAL SUPRAMOLECULAR SYSTEM )

The mixed-metal cluster compound (Me2NH2)6[(SCN)9W3S4SnCl3].0.5H2O (1) with the cubane-type [W3(mu3-S)4Sn] core has been prepared by reactin g W3S44+ in aqueous HCI solution with SnCl2.2H2O in the presence of Me 2NH2Cl and NaSCN. 1 was characterized by X-ray crystallography and by Sn-119 Mossbauer, photoelectron, and electronic absorption spectroscop y. Crystals of 1 are monoclinic, of space group C2/c, with a = 42.792( 10) angstrom, b = 11.988(2) angstrom, c = 21.725(3) angstrom, beta = 9 5.24(2)-degrees, and Z = 8. The structure was refined by full-matrix l east-squares techniques to R = 0.069 and R(w) = 0.071 for 7690 reflect ions with F > 4sigma(F). The formation of 1 is due to a synergetic eff ect: The affinity of the W3S4 ligand for cations like Sn2+ is increase d as its electron-donor strength is increased by the reducing cation i tself. An alternative description would be to insert a plug formed mai nly from the Sn 5s level into a socket formed from acceptor levels loc alized on the W3 triangle, which is equivalent to a novel type of host pest interactions.