A study of the structure and properties of some polynuclear transition metal complexes

Twenty two binuclear copper(ll) complexes based on the ligand 1,3-bis(salicylaldimine)propan-2-ol, (SAL-DPLH3), have been prepared as model compounds for the structure and function of the Type(lll) copper site found in Hemocyanins and Tyrosinase. The complexes are divided into four basic groups, depending on, (1) the type of bridging molecule and/or (2) adducts of the phenylacetate bridged complex. One of these complexes is the superoxide (02-) bridged complex, prepared by a novel synthetic method. The infra-red and visible spectra of the complexes were determined as well as their magnetic properties. The crystal structures of [Cu2(SAL-DPL)pz] and [Cu2(SAL-DPL)PhAc.4-C2H5 -PhOH] are presented. Visible spectra of the complexes indicated that varying the coordination number around one of the copper(ll) atoms in the carboxylate bridged complexes from four to five resulted in a shift to lower energy. Changing the ligand field strength around the copper(ll) atoms by changing the donor atoms from N03 to N202 resulted in a shift to higher frequency. Variable temperature magnetic data show that all complexes, without DMF or pyridine-N-oxide coordinated to one of the copper(ll) atoms, in the carboxylate bridged complexes, have an antiferromagnetic interaction. The strength of the interaction dependant on the nature of the bridging ligand. Coordination of DMF or pyridine-N-oxide to one of the copper(ll) atoms results in a loss of antiferromagnetic interaction.