Copper diimine complexes:: the synthesis and crystal structures of [Cu(C10H14N2)2(MeOH)][BF4], [Cu(C10H20N2)2]Br, [{(C10H14N2)CuBr(μ-OMe)}2(MeOH)] and [{(C10H20N2)CuBr(μ-OMe)}2]

The synthesis and structural characterisation of related novel copper-(I) and -(II) diimine complexes have been described and their application as catalysts for atom transfer polymerisation is noted. The unexpected formation of a methoxy bridged copper(II) diimine complex [{(C10H14N2)CuBr(mu-OMe)}(2)(MeOH)] 3 from the reaction of a copper(I) diimine complex with phenol is described. Compounds 3 and [{(C10H20N2)CuBr(mu-OMe)}(2)] 4 appear to be examples of a rare class of alkoxy bridged Cu-II complexes, with very few similar examples being crystallographically characterised previously.