Antiferromagnetic behavior based on quasi-orthogonal MOs:: Synthesis and characterization of a Cu3 oxidase model

We report the synthesis and structural and magnetic characterization of an original Cu-3 oxidase model. The Schiff base ligand used in the synthesis derives from condensation of acetylacetone with glycine amino acid. The K[Cu-3-(L)(3)(mu(3)-OH)]center dot(H2O)(2) complex crystallizes at room temperature in the tetragonal P4(3)2(1)2 space group with a = 20.540-(3) angstrom and c = 15.866(6) angstrom and consists of triangular Cu-3 units. The magnetic behavior interpretation suggests the presence of spin frustration, which has been investigated by means of ab initio DDCl calculations. It is shown that the system should be viewed as a menage a trois spin-coupled pattern mediated by a central hydroxo group, lifting the doublet degeneracy by similar to 8 cm(-1).