Synthesis and structural chemistry of oxazolinyl-carbene copper(I) complexes

Reaction of a series of directly connected oxazoline–imidazolium salts with potassium tert-butoxide and in the presence of CuBr · SMe2 at −78 °C cleanly gave the corresponding 2-oxazolinyl-(N-mesityl)imidazolidenecopper(I) complexes which are monomeric in solution but aggregate in the solid state. X-ray diffraction studies established a dimeric structure for [{2-(4,4-dimethyl)-oxazolinyl-(N-mesityl)imidazolidene}(bromo)copper(I)]2 (2a) whereas the chiral derivative [{2-(4-S-isopropyl)-oxazolinyl-(N-mesityl)imidazolidene}(bromo)-copper(I)]∝ (2b) forms infinite chains of a coordination polymer.