From oxide to a new type of molecular tungsten compound: formation of bitetrahedral cluster complexes [{W 6 (μ 4 -O) 2 (μ 3 -CCN) 4 }(CN) 16 ] 10- and [{W 6 (μ 4 -O) 2 (μ 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 [{W6(μ4-O)2(μ3-CCN)4}(CN)16]10-. Unexpectedly, it includes the fully deprotonated form of acetonitrile, the CCN3- anion, as a μ3-bridging ligand coordinated to the trigonal faces of the bitetrahedral W6 metallocluster. A similar complex [{W6(μ4-O)2(μ3-As)4}(CN)16]10- containing μ3-As3- ligands instead of μ3-CCN3- ones has been synthesized by the reaction between WO3, As and KCN.