Organoactinide Phosphine/Phosphite Coordination Chemistry. Facile Hydride-Induced Dealkoxylation and the Formation of Actinide Phosphinidene Complexes

Article abstract of DOI:10.1021/ja00322a028

This contribution reports a study of the reaction of the organoactinide hydrides (Cp'2MH2)2 (Cp'=η⁵-(CH3)5C5, M=Th,U) with trimethyl phosphite.Quantitative transposition of hydryde and methoxide ligands occurs to yield the corresponding Cp'2M(OCH3)2 complexes (synthesized independently from Cp'2MCl2 and NaOCH3) and the phosphinidene-bridged methoxy complexes 2PH.The reaction is considerably more rapid for M=U than for M=Th.The new compounds were characterized by elemental analysis, 1H and 31P NMR, infrared spectroscopy, magnetic susceptibility, and D2O hydrolysis.The molecular structure of 2PH has been determined by single-crystal X-ray diffraction techniques.It crystallizes in the monoclinic space group P2/n with a=13.926(3) Angstroem, b=10.765(3) Angstroem, c=15.282(4) Angstroem, β=107.63(2) deg, and Z=2.Full-matrix least-squares refinement of the structural parameters for the 24 independent anisotropic non-hydrogen atoms has converged to R₁ (unweighted, based on F) = 0.041 for 1677 independent absorption-corrected reflections having 2Θ_MoKα<43 deg and I>3?(I).The 2PH molecule has C₂ symmetry, with the μ-PH^2- ligand lying on a crystallographic twofold axis.The coordination geometry about each uranium ion is of the typical pseudotetrahedral Cp'2M(X)Y type, with U-P=2.743(1) Angstroem, U-O=2.046(14) Angstroem, <*>U-P-U=157.7(2) deg, and <*>U-O-C(methyl)=178(1) deg.Evidence is presented that other >P-OR linkages react in a similar manner.