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

Article abstract of DOI:10.1246/bcsj.70.821

Copper(II) complexes [CuL₂(i-PrNH₂)₂·H₂O] (la), [CuL₂(i-PrNH₂)₂] (Ib), [CuL₂(EtNH₂)₂·H₂O] (2a). [CuL₂(EtNH₂)₂]-CHCl₃ (2b), [CuL₂(EtNH₂)₂·H₂O)-2CHCl ₃, (2c), and [CuL₂(EtNH₂)₂·MeOH] (2d) (L = 5.5-diphenylhydantoinate) have been prepared. The crystal structures of la, 2c, and 2d were determined by X-ray analysis. Each CuKtO chromophore is a five-coordinated square-based pyramidal geometry. The axial Cu-O distances arc Cu(l)-O(1)(water) = 2.362(10) A, Cu(l)-O(l)(water) = 2.436(9) A and Cu(1)-O(1)(MeOH) = 2.33(1) A, for complexes la, 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 solutions were determined at room temperature, and a considerable change in ligand field bands was observed. The five-coordinated complexes in the chloroform solutions release their axial water ligand and the CuN4O chromophore converts into a distorted tetrahedral CuN4 chromophore.