Structure of some phosphinoxide complexes of lanthanides

Stereochemistry of phosphinoxide (P O) complexes of REE(3), for which about 20 structures are presently known is considered. It is noted that, with a considerable quantity of synthesized REE complexes containing PO-ligands, only several compounds with the central ion coordination nUmber (CN) below 6 are known. Composition of some complexes is presented. Data on the bond lengths and valence angles in the REE compounds with PO-ligands are tabulated. From an analysis of relative arrangement of ligands around the complex central ion with CN=7, it is shown that the coordination polyhedron (CP) in the form of a one-cap octahedron exhibits a higher relative stability alongside with the complexes with CN=6 and 7. The compositions of complexes with CN=7, 8, 9, 10 are analyzed. PO complexes of REE are shown to possess the same peculiar features as other classes of lanthanide compounds, namely: a wide range of CN and variety of CP forms. A trend to highly asymmetric arrangement of all the ligands in the coordination sphere or, at least, atoms forming CP is traced so in most of the considered structures