Homoleptic uranium(III) imidodiphosphinochalcogenides including the first structurally characterised molecular trivalent actinide-Se bond.

Preparation of U[N(EPPh2)2]3 (E = S or Se) by treating U[N(SiMe3)2]3 with three equivalents of NH(EPPh2)2 is described together with presentation of a hitherto unreported molecular crystal structure containing An(III)-Se bonds (An = actinide).