Conditions for the Formation of Binuclear Copper(II) Complexes with Bridging Hydroxo Groups in the Presence of the closo-Dodecaborate Anion

Approaches are proposed for the synthesis of binuclear cationic copper(II) complexes [ Cu₂^II (BPA)2(μ-OH)2]2+ (BPA is 2,2'-bipyridylamine) (I) and [ Cu₂^II (Bipy)2(μ-OH)2(DMF)2]2+ (Bipy is 2,2'- bipyridyl) (III) stabilized by the closo-dodecaborate anion [B12H12]2–. The approaches are based on the use of precursor complexes {Ph4P[CuI[B12H12]}m (Ph4P is tetraphenylphosphonium) in the case of BPA and {Et4N[Ag[B12H12]}m (Et4N is tetraethylammonium) and [CuII2(Bipy)4(μ-CO3)]Cl2 in the case of Bipy as the starting reagents. The synthesis in the {Ph4P[CuI[B12H12]}m–BPA system was accompanied by the formation of a by-product, {[Cu(BPA)2][B12H12]}m (II), of known structure. The products were characterized by elemental analysis and IR spectroscopy. The structures of [ Cu₂^II (BPA)2(μ-OH)2][B12H12]·2DMF (I·2DMF) and [ Cu₂^II (Bipy)2(μ-OH)2(DMF)2][B12H12]·2DMF (III·2DMF) were determined by X-ray diffraction analysis.