Mixed-metal clusters with a {Re 3 Mo 3 Se 8 } core: from a polymeric solid to soluble species with multiple redox transitions

Cluster compounds based on a new {Re Mo Se } core were obtained and studied. The polymeric solid K [Re Mo Se (CN) (CN) ] (1) containing 24 cluster valence electrons (CVE) was isolated as a result of high-temperature reaction. Water-soluble salts K [Re Mo Se (CN) ]·11H O (2) and Cs [Re Mo Se (CN) ]·H O (3) were prepared from compound 1. Crystal structures of the diamagnetic compounds 2 and 3 contain a cluster anion [Re Mo Se (CN) ] with a 22-electronic core {Re Mo Se } . Metathesis reaction followed by recrystallization from CH CN yielded paramagnetic salt (Ph P) [Re Mo Se (CN) ]·2CH CN (4) containing the {Re Mo Se } core with 21 CVE. Cyclic voltammetry of the solution of 4 displayed three quasi-reversible waves with E = -0.325, -0.818 and -1.410 V vs. Ag/AgCl electrode indicating the presence of [Re Mo Se (CN) ] transitions. Electronic structure calculations showed that both mer- and fac-isomers of [Re Mo Se (CN) ] clusters undergo great distortion when the number of CVE decreases.