Redox chemistry of niobium chalcogenide halides: a mixed valency Nb^III/Nb^IVtetramer. Preparation and crystal structure of a (µ-diselenido-µ-selenido)-tetraniobium complex, Nb₄Br₁₀Se₃(NCMe)₄

Abstract

The reaction of NbBr4(NCMe)2 with Sb2Se3 in MeCN solution yields a tetranuclear adduct Nb4Br10Se3(NCMe)4, in which two of the metal atoms have a valence state of four, the remaining two being tervalent; in the adduct the niobium(III) atoms are not involved in any metal-metal interaction and, since the compound is diamagnetic, they must have a doubly occupied dz2, ground state electronic configuration.