Syntheses, structures and multinuclear NMR (45Sc, 89Y, 31P) studies of Ph3PO, Ph2MePO and Me3PO complexes of scandium and yttrium nitrates

Abstract

The reactions of the tertiary phosphine oxides Ph3PO, Ph2MePO or Me3PO with hydrated yttrium(III) nitrate in ethanol gave the complexes [Y(R3PO)2(EtOH)(NO3)3] (R3PO = Ph3PO or Ph2MePO), [Y(Me3PO)2(H2O)(NO3)3], [Y(R3PO)3(NO3)3] (R3PO = Ph3PO, Ph2MePO or Me3PO), and [Y(Ph3PO)4(NO3)2]NO3. The species [Y(R3PO)4(NO3)2]NO3 (R3PO = Ph2MePO or Me3PO) were formed from [Y(R3PO)3(NO3)3] and an excess of R3PO in CH2Cl2 solution and identified spectroscopically, but have not been isolated as solids. Corresponding reactions of hydrated scandium(III) nitrate produced [Sc(Ph3PO)2(NO3)3], [Sc(Ph2MePO)3(NO3)3], [Sc(Ph2MePO)4(NO3)2]NO3, [Sc(Me3PO)2(EtOH)(NO3)3], and [Sc(Me3PO)6][NO3]3. All complexes were characterised by elemental analysis, IR and 1H NMR spectroscopy and conductance measurements. Variable temperature 89Y, 45Sc and 31P-{1H} NMR spectroscopies have been used to identify species present in solution, and probe the interconversions. 31P-{1H} NMR studies show that exchange with added R3PO in solution is slow on the NMR timescale. Crystal structures were determined for [Y(Ph3PO)2(EtOH)(NO3)3] and [Y(R3PO)3(NO3)3] (R3PO = Ph3PO, Ph2MePO or Me3PO): all contain 9-co-ordinate Y with symmetrically co-ordinated bidentate nitrate groups. Structures of the 8-co-ordinate [Sc(Ph3PO)2(NO3)3] and [Sc(Ph2MePO)4(NO3)2]NO3 are also described.