Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of La(Ph3PO)(4)(NO3)(3) center dot Me2CO and Lu(Ph3PO)(4)(NO3)(2) NO3

Levason, W., Newman, E. H. and Webster, M. (2000) Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of La(Ph3PO)(4)(NO3)(3) center dot Me2CO and Lu(Ph3PO)(4)(NO3)(2) NO3. Polyhedron, 19 (28), 2697-2705. (doi:10.1016/S0277-5387(00)00588-X).

Abstract

The reaction of Ln(NO3)(3). 6H(2)O (Ln = La, Ce, Pr or Nd) with a sixfold excess of Ph3PO in acetone formed [Ln(Ph3PO)(4)(NO3)(3)]. Me2CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH2Cl2 or Me2CO solutions, P-31 NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph3PO)(3)(NO3)(3)] and Ph3PO. Similar reactions in ethanol gave [Ln(Ph3PO)(3)(NO3)(3)] only. In contrast for Ln = Sm, Eu or Gd. only the [Ln(Ph3PO)(3)(NO3)(3)] are formed from either acetone or ethanol solutions. For the later lanthanides Ln = Tb-Lu, acetone solutions of Ln(NO3)(3). 6H(2)O and Ph3PO gave [Ln(Ph3PO)(3)(NO3)(3)] only, even with a large excess of Ph3PO, but from cold ethanol [Ln(Ph3PO)(4)(NO3)(2)]NO3 (Ln = Tb, Ho-Lu) were obtained. The structure of [Lu(Ph3PO)(4)(NO3)(2)]NO3 shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH2Cl2 or Me2CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph3PO)(3)(NO3)(3)]. [Ln( Ph3PO)(4)(NO3)(2)]NO3 and Ph3PO as judged by P-31{H-1} NMR spectroscopy. The [Ln(Ph3PO)(3)(NO3)(3)] also partially decompose in solution for Ln = Dy-Lu. forming some tetrakis(phosphine oxide) species.

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