Phosphenium complexes 30. Supermesitylphosphenium complexes of molybdenum and tungsten: Synthesis and exchange reactions involving the P-H bond

Article abstract of DOI:10.1016/S0022-328X(98)00947-4

Deprotonation of the complex salts {Cp(OC)₃[H₂(2,4,6-tBu₃-C₆H ₂)P]M}BF₄ (M=Mo, W) (4a,b), obtained from [Cp(OC)₃M]BF₄ (2a,b) and (2,4,6-tBu₃-C₆H₂)PH₂ (3), yields the metallo-phosphanes Cp(OC)₃M-P(H)(2,4,6-tBu₃-C₆H₂) (5a,b). 5a,b are thermally decarbonylated to the PH-functionalized phosphenium complexes Cp(OC)₂M=P(H)(2,4,6-tBu₃-C₆H₂) (7a,b), which can also be obtained by the base-assisted dehydrohalogenation of the bifunctional complexes Cp(OC)₂[H₂(2,4,6-tBu₃C₆H ₂)P]M-Cl (9a,b), prepared by a ligand exchange reaction from Cp(OC)₃M-Cl (8a,b) and 3. The reaction of 7a,b with CCl₄ affords the chloro-substituted phosphenium complex Cp(OC)₂M=P(Cl)(2,4,6-tBu₃-C₆H₂) (10a,b) via H/Cl exchange at the sp²-phosphorus. Substitution of the P-bonded hydrogen by a methyl group is achieved by in situ deprotonation of 7b and subsequent treatment with methyliodide, yielding the diorgano-phosphenium complex Cp(OC)₂M=P(Me)(2,4,6-tBu₃-C₆H₂) (11).