Synthesis and structural characterization of the molecular loop [cis-Mo2(N,N′-di-p-anisylformamidinate)2]2(O2C–CHCCH–CO2)2

A new molecular loop composed of two quadruply bonded Mo2(DAniF)2 units (DAniF=N,N′-di-p-anisylformamidinate) linked by two chiral allene-1,3-dicarboxylate anions has been prepared from the reaction of [cis-Mo2(DAniF)2(MeCN)4](BF4)2 with the bis(tetraethylammonium) salt of allene-1,3-dicarboxylic acid. This compound, [cis-Mo2(DAniF)2]2(O2C–CHCCH–CO2)2 (1), has been characterized by X-ray crystallography and by 1H NMR and UV–Vis spectroscopy. The molecule possesses a center of inversion and hence is meso. There is only weak electronic coupling between the two Mo2 4+ units as revealed by electrochemical measurements.