Oxidation and acidolysis of MoH4(PR3)4

Article abstract of DOI:10.1021/ic00142a015

MoH₄(PMe₂Ph)₄ reacts with 2 mol of AgBF₄ in MeCN to give [MoH₂(PMe₂Ph)₄(NCMe)₂](BF ₄)₂, characterized by spectroscopic methods and X-ray crystallography as containing a fluxional dodecahedral dication. Reaction with equimolar AgBF₄ gives no new product but only a reduced yield of the same salt. This oxidation is thus followed by reductive elimination of H₂ so that the molybdenum oxidation state suffers no net change. The same salt is obtained by treating the tetrahydride with 2 mol of HBF₄·OEt₂ in acetonitrile. The identity of the phosphine affects the product isolated: MoH₂(PMePh₂)₄, upon treatment with AgBF₄ or HBF₄·OEt₂ in MeCN, yields MoH₂(PMePh₂)₃(NCMe)₃²⁺ with liberation of 1 mol of PMePh₂. Possible mechanisms are discussed, as is the relationship between silver oxidation and acidolysis. Crystallographic data (at -160°C) for [MoH₂(PMe₂Ph)₄(NCMe)₂](BF ₄)₂: monoclinic space group P2₁ with a = 12.359 (6) A?, b = 33.323 (2) A?, c = 13.048 (6) A?, β = 128.61 (2)°, Z = 4. R(F) = 0.0673 for 5037 data collected by diffractometer.