SYNTHESIS OF THE FIRST NEUTRAL SPIRO SELENIUM(II) COMPLEX CONTAINING A TRUE SQUARE-PLANAR SE(SE-4) CORE - PREPARATION AND CRYSTAL-STRUCTUREOF PHOSPHANYLSELENOYL)-P,P-DIPHENYLPHOSPHANYLSELENOIC AMIDATO-SE,SE']SELENIUM(II)

The phosphanylselenoyl)-P,P-diphenylphosphanylselenoic amidato-Se,Se'] selenium(II) (1) was prepared by treating [K{N(SePPh2)(2)}] with [Se{S 2P(O-iPr)(2)}(2)] in THF. The title compound was characterized by mean s of IR and P-31-NMR spectroscopy and positive-ion FAB mass spectromet ry and elemental analysis. The molecular structure was determined usin g single-crystal X-ray diffraction. The Se(Se-4) core exhibited a quas i perfect square planar geometry. Two selenide ligands are coordinated symmetrically to the central atom forming a spiro complex.