True square planar [M{N(SePiPr2)2-Se,Se'}2][M = Sn, Se] complexes. An extraordinary geometrical arrangement for well known centers [Sn(II), Se(II)].

The syntheses and molecular structures of [M{N(SeP(i)Pr2)2-Se,Se'}2][M = Sn(2), Se(3)] are described, these complexes consist of discrete, monomeric molecules featuring MSe4 cores that comprise true square-planar geometries.