Structural Characterization and Magnetic Properties of Triply Carboxylato-Bridged Dinuclear Copper(II) Complexes

A new series of carboxylato-bridged dinuclear copper(II) complexes ([Cu2(Ph2CHCOO)3(bpy)2]BF4 (1), [Cu2(Ph2CHCOO)3(bpy)2]CF3SO3 (2; blue form), [Cu2(Ph2CHCOO)3(bpy)2]CF3SO3 (3; green form), [Cu2(Ph2CHCOO)3(phen)2]BF4 (4), [Cu2{(ClPhO)2CHCOO}3(bpy)2]BF4 (5), and [Cu2{(ClPhO)2CHCOO}3(bpy)2]ClO4 (6), where Ph2CHCOO, (ClPhO)2CHCOO, bpy, and phen are diphenylacetate anion, bis(4-chlorophenoxy)acetate anion, 2,2′-bipyridine, and 1,10-phenanthroline, respectively) has been prepared. X-Ray crystallographic analyses reveal that complexes 1—6 have a triply carboxylato-bridged dicopper(II) core. Two copper(II) ions in 1 and 2are linked by one familiar “syn–syn bridging” carboxylate and two unique “monatomic bridging” carboxylates. In 3—6, two “syn–syn bridging” carboxylates and one “monatomic bridging” carboxylate connect two copper(II) ions. Complexes 2 and 3 are geometrically isometric with each other. Magnetic susceptibility data for the present complexes indicate that a weak antiferromagnetic interaction is operative in each dicopper core in 1, 2, 4, 5, and 6 with 2J values ranging from −5 to −13 cm−1, whereas a ferromagnetic coupling is operative in 3 with a 2J value of 9 cm−1.