Actinide structural studies. Part 8. Some new oxygen-donor complexes of trichloro(cyclopentadienyl)neptunium(IV); the crystal structure of trichloro(η5-cyclopentadienyl)bis(methyldiphenylphosphine oxide)neptunium(IV)

Abstract

The complexes Np(cp)Cl₃·2L [cp =η⁵-C₅H₅; L = dimethylformamide (dmf), McCONPrⁱ₂, PMe₃O, EtCONPrⁱ₂, PMe₂PhO, or PMePh₂O] have been prepared. The crystal and molecular structure of [Np(cp)C1₃(PMePh₂O)₂] has been determined from three-dimensional X-ray diffraction data and refined by least squares to R= 0.061 for 4 248 observed [I/σ(I) 3.0] reflections. The complex crystallises in space group P1₂/c, with a= 10.199(4), b= 33.208(13), c= 20.661(7)Å, β= 113.04(2)°, and Z= 8. The neptunium atom is octahedrally co-ordinated, with the two PMePh₂O ligands in cis positions, so that the cyclopentadienyl group is trans to one PMePh₂O ligand. I.r. and near- i.r.–visible absorption spectra (dichloromethane solution) are reported.