Chemistry of phosphido-bridged dimolybdenum complexes. Part 1. High-yield synthesis of [Mo2(η5-C5H5)2(µ-H)(µ-PPh2)(CO)4] and its reactions with organophosphorus ligands: X-ray crystal structure of [Mo2(η5-C5H5)2(µ-H)-(µ-PPh2)(CO)3{P(OMe)3}]

Abstract

The thermal reaction of [Mo₂(η⁵-C₅H₅)₂(CO)₆] with PPh₂H in toluene or decalin gives [Mo₂(η⁵-C₅H₅)₂(µ-H)(µ-PPh₂)(CO)₄](1a) in high yield. An analogous reaction with PPhH₂ affords [Mo₂(η⁵-C₅H₅)₂(µ-H)(µ-PPhH)(CO)₄](1b). The photolytic reaction of (1a) with organophosphours ligands, L, gives the monosubstituted complexes [Mo₂(η⁵-C₅H₅)₂(µ-H)(µ-PPh₂)(CO)₃L][L = P(OMe)₃,P(OPh)₃,PPh₃,P(C₆H₄Me-m)₃, PEt₂Ph, or dppm-P(dppm = Ph₂PCH₂PPh₂)]. ¹H N.m.r. spectroscopy reveals that each of the monosubstituted products exists as an equilibrium mixture of two isomers in solution, the position of the equilibrium depending on the ligand L and on the solvent. The structure of [Mo₂(η⁵-C₅H₅)₂(µ-H)(µ-PPh ₂)(CO)₃{P(OMe)₃}] in the solid state has been determined by a single-crystal X-ray analysis.