Structures of Bis(5,5-diphenylhydantoinato)copper(II) Complexes with Primary Amines Involving Square Pyramidal CuN4O Chromophores

Copper(II) complexes [CuL2(i-PrNH2)2·H2O] (1a), [CuL2(i-PrNH2)2] (1b), [CuL2(EtNH2)2·H2O] (2a), [CuL2(EtNH2)2]·CHCl3 (2b), [CuL2(EtNH2)2·H2O]·2CHCl3 (2c), and [CuL2(EtNH2)2·MeOH] (2d) (L = 5,5-diphenylhydantoinate) have been prepared. The crystal structures of 1a, 2c, and 2d were determined by X-ray analysis. Each CuN4O chromophore is a five-coordinated square-based pyramidal geometry. The axial Cu–O distances are Cu(1)–O(1)(water) = 2.362(10) A, Cu(1)–O(1)(water) = 2.436(9) A and Cu(1)–O(1)(MeOH) = 2.33(1) A, for complexes 1a, 2c, and 2d, respectively. Intramolecular hydrogen bonds are formed between the carbonyl oxygens and amino hydrogens (C=O···H–N) as well as the axial ligand (C=O···H–O). The latter hydrogen bonds stabilize the axial ligand for coordination. Moreover, double intermolecular hydrogen bonds link the 5,5-diphenylhydantoinate ligands (C=O···H–N) belonging to be adjacent complex molecules in all three complexes. The electronic spectra of the complexes in the solid state and in chloroform s...