6533b823fe1ef96bd127f37c

RESEARCH PRODUCT

C—br insertion reactions in rhodium and iridium compounds containing an ortho-halo-arylphosphine. X-ray structures of two ortho-metallated compounds of formula IrX2[P(C6F4)Ph2][P(o-BrC6F4)Ph2], (X = Cl, Br)

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Abstract A comparative study of the reaction of rh and ir complexes with the ortho-bromo-arylphosphine PCBr [PCBr = P(o-BrC6F4)(C6H5)2], is presented. Various PCBr complexes of Ir(I) and Rh(I) undergo rapid insertion of the metal atom into a CBr bond provided the phosphine is coordinated in a η2-mode (Pbr). If the Br coordination is substituted by a superior ligand such as CO or an olefin, no reaction occurs under normal conditions. PCBr complexes of the tervalent metals require a two-electron reduction step prior to the ortho-metallation reaction. Most intermediates were characterized by chemical and spectroscopic analysis. Two intermediates of general formula IrX2(η2-PC)(η-PCBr), [PC = P(C6F4)(C6H5)2] (X = Cl, 5, X = Br, 6), were characterized by a single crystal analysis. 5 crystallizes in the monoclinic space group P21/n with cell dimensions a = 14.741(5) A, b = 13.558(5) A, c = 18.303(7) A, β = 112.35(2)°, Z = 4. 6 crystallizes in the same space group P21/n and has cell dimensions a = 19.05(1) A, b = 19.554(6) A, c = 20.337(5) A, β = 93.63(5)°, Z = 8. Both compounds have distorted octahedral coordination around the metal centre.