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

The reactions of the tertiary phosphine oxides Ph3PO, Ph2MePO or Me3PO with hydrated yttrium(III) nitrate in ethanol gave the complexes [Y(R3PO)(2)(Et OH)(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. T he 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 identifi ed spectroscopically, but have not been isolated as solids. Corresponding r eactions 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 H-1 NMR spectroscopy and conductance measurement s. Variable temperature Y-89, Sc-45 and P-31-{H-1} NMR spectroscopies have been used to identify species present in solution, and probe the interconve rsions. P-31-{H-1} NMR studies show that exchange with added R3PO in soluti on 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 M e3PO): all contain 9-co-ordinate Y with symmetrically co-ordinated bidentat e nitrate groups. Structures of the 8-co-ordinate [Sc(Ph3PO)(2)(NO3)(3)] an d [Sc(Ph2MePO)(4)(NO3)(2)]NO3 are also described.