Mixed-ligand fluorocuprates(II). Synthesis and characterisation of [CuF3L(H2O)2]− containing amino acids as coligands

Abstract

Complex species of the type NH4[CuF3L(H2O)2] · nH2O (L = glycine, n = 1; 1-alanine, n = 0) have been prepared by reacting hydrated copper(II) oxide, CuO · nH2O, with the amino acids in the presence of bifluoride, HF2−, in aqueous solution. The order of addition of the ligands, fluoride and amino acids is crucial to the synthesis. A reaction solution pH lower than the isoelectric point of the respective amino acids seems to favour the formation of mixed-ligand fluoro complexes. Occurring as zwitterions, the amino acids in the complexes have been shown to be bonded to the copper(II) centre via the carboxyl (—COO−) moiety representing an unexpected non-chelated form of the coligands. Magnetic moments and e.s.r. data are consistent with six-coordinate copper(II) complexes.