Fluorinated Tris(pyrazolyl)borate Ligands without the Problematic Hydride Moiety: Isolation of Copper(I) Ethylene and Copper(I)−Tin(II) Complexes Using [MeB(3-(CF₃)Pz)₃]^-

The thallium derivative of a fluorinated, B-methylated, tris(pyrazolyl)borate ligand, [MeB(3-(CF3)Pz)3]-, has been synthesized via a two-step process using the corresponding pyrazole, Li[MeBH3], and thallium(I) acetate. Reaction of [MeB(3-(CF3)Pz)3]Tl with CuBr in the presence of ethylene leads to [MeB(3-(CF3)Pz)3]Cu(C2H4). It is a thermally stable solid. [MeB(3-(CF3)Pz)3]Cu(C2H4) reacts with [(Bn)2ATI]SnCl to yield [MeB(3-(CF3)Pz)3]Cu←Sn(Cl)[(Bn)2ATI], featuring an unsupported Cu(I)−Sn(II) bond [2.4540(4) Å].