Dinuclear [{(π-C3H5)M(PR3)}2(μ-X)]Y Complexes of Nickel and Palladium

Abstract

The double halide-bridged π-allyl complexes {(η 3 -C 3 H 5 )M(μ-X)} 2 (M = Ni, Pd; X = Cl, Br) resist halide abstraction by thallium salts of weakly coordinating anions Y = PF 6 , B(C 6 F 5 ) 4 , and B{C 6 H 3 (CF 3 ) 2 } 4 in noncoordinating CH 2 Cl 2 . In the presence of a bulky phosphine (P i Pr 3 , P t Bu 3 ) or when 2 equiv of (η 3 -C 3 H 5 )M(PR 3 )X is reacted with TlY, one of the halide ions is replaced to afford the ionic dinuclear, single halide-bridged complexes [{(η 3 -C 3 H 5 )M-(PR 3 )} 2 (μ-X)]Y (M = Ni, X = Br (6, 7); M = Pd, X = Cl (8, 9) and Br (10, 11)), which do not react with further TlY. The corresponding complexes with Y = Al{OC(CF 3 ) 3 } 4 have also been prepared. In addition, it has been found that the dinuclear palladium complexes, but not the nickel derivatives, are also stable for Y = OTf. According to NMR the complexes represent a mixture of diastereomers in solution. For [{(η 3 -C 3 H 5 )Ni(PiPr 3 )} 2 (μ-Br)][Al{OC(CF3) 3 } 4 ] (6c) and [{(η 3 -C 3 H 5 )Pd(PtBu 3 )} 2 (μ-Br)][B(C 6 F 5 ) 4 ] (11b) the crystal structures have been determined. The reaction of (η 3 -C 3 H 5 )M(PMe 3 )X with TlY affords a mixture of [(η 3 -C 3 H 5 )M-(PMe 3 ) 2 ]Y (described for M = Ni, Y = PF 6 (12) and M = Pd, Y = PF 6 (13)) and the starting phosphine-free {(η 3 -C 3 H 5 )M(μ-X)} 2 .