Eight coordinate 1,2-bis(dimethylarsino) and 1,2-bis(dimethylphosphino)-benzene complexes of uranium tetrachloride, UCl4[(1,2-Me2E)2C6H4]2 where E is As or P

Abstract

The eight coordinate complexes of 1,2-bis(dimethylarsino)benzene, MCl4(diars)2 where M is Th or U, and 1,2-bis(dimethylphosphino)benzene, UCl4(diphos)2, are prepared and characterized. Both coordination complexes of uranium crystallize in the tetragonal crystal system in space group I4¯2m, in which the geometry is a D2d-dodecahedron. In solution the uranium complexes do not exchange with added free ligand on the NMR time scale but they undergo bidentate ligand exchange on the chemical time scale. The 31P{1H} NMR chemical shifts of UI4(diphos)2 and UX4(dmpe)2, X=Cl, Br, I range from 1500 to 2100ppm and are strongly dependent on temperature.