From oxide to a new type of molecular tungsten compound: formation of bitetrahedral cluster complexes [{W6(4-O)2(3-CCN)4}(CN)16]10- and [{W6(4-O)2(3-As)4}(CN)16]10-

Tungsten trioxide has been found to be a convenient precursor for the synthesis of metal cluster compounds with new types of cluster cores. The reaction between WO3 and KCN led to the formation of the cluster complex [{W-6((4)-O)(2)((3)-CCN)(4)}(CN)(16)](10-). Unexpectedly, it includes the fully deprotonated form of acetonitrile, the CCN3- anion, as a (3)-bridging ligand coordinated to the trigonal faces of the bitetrahedral W-6 metallocluster. A similar complex [{W-6((4)-O)(2)((3)-As)(4)}(CN)(16)](10-) containing (3)-As3- ligands instead of (3)-CCN3- ones has been synthesized by the reaction between WO3, As and KCN.