Neutral Mo6Q8-clusters with terminal phosphane ligands – a route to water-soluble molecular units of Chevrel phases

Despite the numerous studies on Chevrel phases, their building blocks – molecular compounds containing the {Mo6Q8} cluster core – are hardly presented in the literature. Here we present rare examples of phosphane molybdenum chalcogenide clusters – [{Mo6Q8}(Ph2PC2H4COOH)6] (Q = S or Se) – which have been obtained by the direct interaction of (Bu4N)2[{Mo6Cl8}Cl6] with in situ generated Na2Q in the presence of a phosphane pro-ligand. Crystal structure determination has confirmed the formation of a homoleptic six-substituted neutral complex. The redox and optical properties were also studied. Due to the presence of six carboxylate groups in phosphane ligands, both clusters form a stable solution in alkaline water. Besides the known K7[{Mo6Se8}(CN)6]·8H2O, the compounds obtained here are the only examples of water-soluble complexes of such types.