SPIN-EXCHANGE COUPLING IN HETEROBIMETALLIC M(II)V(IV)O (M = CU, NI, CO, FE, MN) MACROCYCLIC COMPLEXES - SYNTHESIS, STRUCTURE, AND PROPERTIES

A series of heterobimetallic complexes [((VO)-O-IV)L1Cu(II)(mu-OAC)(Me OH)](ClO4) (1) and [((VO)-O-IV)L1M(II)(mu-OAc)(H2O)](ClO4). H2O (M = N i (2), Co (3), Fe (4), Mn (5)) derived from a symmetric tetraaminodiph enol macrocyclic ligand H(2)L1 have been synthesized and characterized . The crystal structure of 1 has been determined. The complex (C27H41N 4O10ClCuV) crystallizes in the monoclinic space group P2(1)/c with a = 13.227(3) Angstrom, b = 14.932(3) Angstrom, c = 17.019(3) Angstrom, b eta = 112.29(1)degrees, and Z = 4. Both the metal centers in 1 are six -coordinated and are triply bridged by the two phenolate and the aceta te oxygens; the sixth coordination site of the copper atom is occupied by a distantly placed methanol oxygen (Cu-O = 2.452(5) Angstrom), whi le that of the vanadium by the oxo oxygen (V-O = 1.627(4) Angstrom). T he metal centers are separated by 3.066(1) Angstrom, and the dihedral angle (a) between the metal planes is 32.0 degrees. Variable-temperatu re (4-300 K) magnetic susceptibility measurements of 1-5 and of [((VO) -O-IV)L2Cu(II)(mu-OAc)(H2O)](ClO4) (6) (where H(2)L2 is an asymmetric tetraaminodiphenol macrocyclic ligand) have been made and treated with the spin-Hamiltonian H = -2/S-1.S-2 All the complexes, except 5, exhi bit ferromagnetic exchange interaction with the following values of J (in cm(-1)): 42.5 (1), 12.0 (2), 4.4 (3), 4.4 (4), and 46.0 (6); compl ex 5 behaves antiferromagnetically with J = -14.2 cm(-1). A linear cor relation between J and A has been proposed for (CuVO)-V-II-O-IV comple xes.