Co-ordination behaviour of N-protected amino acids. Structural and spectroscopic study of complexes of Co II , Ni II and Cu II with N-(4-aminobenzoyl)glycine

Abstract

The structural and spectroscopic properties of complexes of N-(4-aminobenzoyl)glycine (HL) with CoII, NiII and CuII have been investigated. The complex [{CoL2(H2O)2}n]·2nH2O crystallizes in the space group P, with a= 8.027(2), b= 8.031(2), c= 10.033(1)A, α= 96.52(2)°, β= 100.17(2)°, γ= 119.19(2)° and Z= 1; the nickel(II) homologue is isomorphous. The complex [(CuL2)n]·4nH2O crystallizes in the space group P21/n, with a= 4.673(1), b= 20.476(1), c= 12.026(1)A, β= 97.38(2)° and Z= 2. The cobalt(II) co-ordination geometry is tetragonally distorted octahedral with four oxygens from two water molecules and two carboxylate groups in the basal plane and two amino nitrogens in the apical position. The copper(II) complex shows a strongly distorted tetragonal-octahedral geometry with two oxygens and two amino nitrogens of different amino acidate anions in the basal plane and two oxygens in the off-z-axis position. The ligand acts as bidentate bridging giving rise to a polymeric one-dimensional chain in the cobalt(II) complex and two-dimensional layers in the copper(II) one.