Synthesis and structure of heavier group 2 metal complexes with diselenoimidodiphosphinato ligand containing Sr–Se and Ba–Se direct bonds

We report the mononuclear diselenoimidodiphosphinato strontium and barium complexes of the molecular formula [{η2-N(PPh2Se)2}2Sr(THF)2] (2) and [{η2-N(PPh2Se)2}2Ba(THF)3] (3) which can be obtained by two routes, either by the treatment of metal bis(trimethylsilyl)amide and diselenoimidodiphosphine (1) via the elimination of silylamine or salt metathesis reaction involving metal diiodide and potassium salt of diselenoimidodiphosphine. In the solid state structures of 2 and 3, each of the metal atom is ligated by four selenium atoms from two diselenoimidodiphosphinato ligand moieties and two (for 2) and three (for 3) THF molecules to adopt a distorted octahedral geometry around the strontium atom and distorted pentagonal bipyramidal geometry for barium ion. In the complexes 2 and 3, a direct metal selenium contact is observed. Additionally we also report the synthesis and structure of lithium complex [η2-N(PPh2Se)2Li(THF)2] (4) which was synthesized by using 1 and LiCH2SiMe3 in THF solution.