Synthetic and structural studies of some actinide complexes with neutral donor ligands

Abstract

A series of complexes has been prepared between the aromatic amine N-oxides and tetravalent thorium and uranium. Complexes of thorium and uranium tetrahalides, tetrathiocyanates and tetranitrates have been characterised with pyridine oxide and its substituted derivatives, quinoline oxide, acridine oxide, and the bidentate ligands, bipyridyl dioxide and phenanthroline monoxide. The uranium complexes were susceptible to oxidation and, where possible, the oxidised (uranyl) products have been characterised. New complexes of thorium tetranitrate and thorium and uranium tetrathiocyanate have also been prepared with phosphine oxide ligands. The crystal and molecular structures of three tetravalent actinide complexes have been analysed by X-ray crystallography to determine their polyhedral symmetries. The complexes, U(NCS)4(TMPO)4, Th(NCS)4(TMU)4 and ThCl4(DPSO)4 (TMPO = trimethylphosphine oxide, TMU = tetramethylurea, DPSO = diphenylsulphoxide) all possess octacoordinate structures which have been described in terms of the expected (idealised) geometries.