This contribution reports a study of the reaction of the organoactinide hydrides (Cp'2MH2)2 (Cp' = ƞ5-(CH3)5C5, M = Th, U) with trimethyl phosphite. Quantitative transposition of hydride 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 [Cp'2M(OCH3)]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 [Cp'2U(OCH3)]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) Å, b = 10.765 (3) Å, c = 15.282 (4) Å, β = 107.63 (2)°, 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 2θMoKα < 43° and I < 3σ(7). The [Cp'2U(OCH3)]2PH molecule has C2 symmetry, with the μ-PH2-. ligand lying on a crystallographic twofold axis. The coordination geometry about each uranium ion is of the typical “ seudotetrahedral” Cp'2M(X)Y type, with U-P = 2.743 (1) Å, U-O = 2.046 (14) Å, ∠U-P-U = 157.7 (2)°, and ∠U-O-C(methyl) = 178 (1)°. Evidence is presented that other >P-OR linkages react in a similar manner.
ASJC Scopus subject areas
- Colloid and Surface Chemistry