Structural characterization of copper(I) complexes supported by β-diketiminate ligands with different substitution patterns

Copper(I) complexes generated by using a series of beta-diketiminate ligands (L-R1,R2(R3-), [(R-3)N-C(R-2)-C(R-1)C(R-2 2)-N(R-3)](-), see Chart 1; beta-diketiminate denotes enaminone imine analogs) have been structurally characterized by X-ray crystallographic analysis. In the alpha-nitro-ligand system (R-1 = NO2 and R-2 = H), the structure of the resulting products were largely affected by the nitrogen substituent R-3, providing bis(beta-diketiminato)copper(II) complex 1 [a product of the disproportionation reaction of copper(I)] (R-3 = Ph), head-to-tail linear coordination polymer copper(I) complex 2 (R-3 = Mes, (mesityl)), and mononuclear copper(I) complex 3 (R-3 = Dipp (2,6-diisopropylphenyl)). On the other hand, alpha-cyano-ligand (R-1 = CN and R-2 = H or Me) always gave head-to-tail coordination polymer copper(I) complexes (4-8) regardless of the aromatic substituent R-3. In both systems, beta-diketiminate ligands exhibited a U-shaped closed conformation, forming a six-membered chelate ring with copper(I). Copper(I) complexes with a beta-diketiminate ligand with a W-shaped open conformation were also obtained in the case of alpha-methyl and alpha-hydrogen derivatives (R-1 = Me or H, R-2 = H, and R-3 = Dipp). In these cases, the dinuclear and tetranuclear copper(l) macrocyclic complexes 9 and 10 were obtained.