Heterocubane Phosphoraniminato Complexes of Cadmium

Abstract

Phosphoraniminato complexes of cadmium [CdX(NPEt3)]4 {X = Cl (1), Br (2), I (3), [CdI(NPMe3)]4 (4)} are formed by the reaction of cadmium dihalides with silylated phosphoranimines Me3SiNPR3 (R = Me, Et) in the presence of a fluoride source, e.g. NaF, at elevated temperatures. High yields can be achieved when R = Et and X is a heavy halogen. The exocyclic bromo function in complex 2 can be replaced by reaction with organolithium reagents to give organocadmium compounds [CdMe(NPEt3)]4 (5) and [Cd(C2SiMe3)(NPEt3)]4 (6) in excellent yields. Complexes 1−6 consist of a [Cd4N4] heterocubane core in which the cadmium atoms are linked by μ3-N bridges of the phosphoraniminato ligand with the cubane angles being close to 90°. The crystal structure of an unsymmetrical cubane [Cd4I4(OSiMe3)(NPEt3)3] (7) is reported, in which one of the phosphoraniminato moieties has been replaced by a silyloxy function. All complexes are colorless oxygen- and moisture-sensitive crystalline materials, the heterocubane structure of whic...