Homoleptic Arylcopper Complexes
New arylcopper complexes have been synthesised and characterised structurally. The reaction between the Grignard reagent (viph)MgBr (viph = ortho-vinylphenyl) and CuCl has been studied and two unstable mixed aryl/halide intermediates, [Mg(THF)6][Cu5(viph)2Br4]2.THF and [Mg(THF)5Cl][Cu5(viph)4Br2].T HF, were isolated and found to reduce the yield of [Cu4(viph)4] markedly. The crystal structures of the two intermediates were determined and were found to exhibit unusual coordination geometries for copper(I) and provide mechanistic information. Mesitylcopper has been shown to be predominantly tetrameric in solution and a tetrameric phase has been isolated. Pentamethylphenylcopper has also been found to be a square planar complex. An aryl cuprate, [Cu5(C4H3S)6]-, has been isolated as a magnesium salt. The square planar tetrameric structure is found to be that most commonly encountered, both in solution and solid state, for neutral homoleptic arylcopper complexes without coordinating heteroatoms. Cocrystallisation is proposed as a method of growing X-ray quality crystals.