NEW ORGANOPHOSPHORUS LIGANDS - 1,1,4,4-TETRAKIS(DIPHENYLPHOSPHANYL)BUTATRIENE AND ITS TETRASULFIDE

Treatment of bis(diphenylphosphanyl)ethyne with potassium diphenylphos phide in tetrahydrofuran leads to the formation of tetraphenyldiphosph ane Ph2P-PPh2 and the title compound (Ph2P)2C=C = C=C(PPh2)2 (1). A me chanism is proposed for this process. Compound 1 reacts with elemental sulfur to give the tetrasulfide [Ph2(S)P]2C=C=C=C[P(S)Ph2]2 (2). The crystal structures of 1 and 2 have been determined by single-crystal X -ray diffraction. In both cases the linear butatriene unit shows stron gly alternating C=C bond lengths as predicted in theoretical studies.