Electrophilic addition reactions of the Lewis acids B(C6F5)2R [R = C6F5, Ph, H or Cl] with the metallocene hydrides [M(η-C5H5)2H2] (M = Mo or W), [Re(η-C5H5)2H] and [Ta(η-C5H5)2H3]

Abstract

The syntheses of the new compounds [W(η-C₅H₅)(η-C₅H₄{B(C₆F₅)₂R})H₃], where R = (C₆F₅) 1, Ph 2, H 3 or Cl 4, [Mo(η-C₅H₅)₂(H)(η¹-HB(C₆F₅)₃)] 5, [Mo(η-C₅H₅)₂(H)(η¹-H₂B(C₆F₅)₂)] 6, [Mo(η-C₅H₄Me)₂(H)(η¹-HB(C₆F₅)₃)] 7, [Re(η-C₅H₅)(η-C₅H₄B(C₆F₅)₃)H₂]·0.5C₆H₅Me 8, [Ta(η-C₅H₅)₂(H)₂(η¹-HB(C₆F₅)₃)] 9 and [Re(η-C₅H₅)(η-C₅H₄{B(C₆F₅)₂})(C₆F₅)] 10 are described. The crystal structures of compounds 4 and 10 have been determined. Initial electrophilic addition of the Lewis acid B(C₆F₅)₃ occurs either by exo-addition to a carbon of a η-cyclopentadienyl ring with formation of an exo-{(C₆F₅)₃B}C₅H₅, or by formation of an M–μ-H–B two-electron three-centre bond.