Synthesis and Characterization of Copper Complexes with (CuCuI)-Cu-I, Cu(15)Cu(1.5)m and (CuCuII)-Cu-II Core Structures Supported by a Flexible Dipyridylamide Ligand

摘要

A series of copper complexes supported by a simple dipyridylamide ligand (H(2)pcp) were isolated and characterized. Treatment of H(2)pcp with NaH and copper(I) salts led to the formation of [Cu-2((2)pcp)(2)] (la) and {NaRCu2((2)pcp)(2))(2)]PF6}(n) (1b). The X-ray crystal structures of both complexes feature (CuCuI)-Cu-I cores with close Cu center dot center dot center dot Cu interactions. Electrochemical studies of la showed a reversible one-electron oxidation wave in CH2Cl2. On the basis of the work on la, we began studying the mixed-valence copper species supported by this ligand. The reaction of H(2)pcp with Cu(OAc)(2) and CuCl in different stoichiometries yielded [Cu-2((2)pcp)(2)Cl] (2) and [Cu-3((2)pcp)(2)Cl-2] (3). X-ray crystallography and spectroscopic characterization suggested delocalized (CuCu1.5)-Cu-1.5 core structures of both compounds. These results further inspired us to explore the coordination properties of H(2)pcp toward Cull ions. The complexes [HNEt3][Cu-2((2)pcp)(3)(ClO4)](ClO4) (4a), [Cu-2((2)pcp)(3)(NO3)] (4b), and [Cu-2((2)pcp)(3)(H2O)]BF4 (4c) featuring dinuclear (CuCuII)-Cu-II cores were prepared and characterized by X-ray crystallography and spectroscopic methods. Structural analysis of these complexes accommodation of (CuCuI)-Cu-I, (CuCu1.5)-Cu-1.5, and (CuCuII)-Cu-II is attributed to the structural flexibility of the ligand H(2)pcp. Complexes la, 2, 3, and 4a were examined by X-ray photoelectron spectroscopy, which confirmed the oxidation state assignments. Computational studies were also performed to provide insight into the electronic structures of these complexes.