Structural characterization and magnetic properties of triply carboxylato-bridged dinuclear copper(II) complexes

A new series of carboxylato- bridged dinuclear copper(II) complexes ([Cu-2( Ph2CHCOO)(3)(bpy)(2)]BF4 (1), [Cu-2(Ph2CHCOO)(3)(bpy)(2)]CF3SO3 (2; blue fo rm), [Cu-2(Ph2CHCOO)(3)(bpy)(2)]CF3SO3 (3; green form), [Cu-2(Ph2CHCOO)(3)( phen)(2)]BF4 (4), [Cu-2{(ClPhO)(2)CHCOO}(3)(bpy)(2)]BF4 (5), and [Cu-2{(ClP hO)(2)CHCOO}(3)(bpy)(2)]ClO4 (6), where Ph2CHCOO, (ClPhO)(2)CHCOO, bpy, and phen are diphenylacetate anion, bis(4-chlorophenoxy)acetate anion, 2,2'-bi pyridine, and 1,10-phenanthroline, respectively) has been prepared. X-Ray c rystallographic analyses reveal that complexes id have a triply carboxylato -bridged dicopper(II) core. Two copper(II) ions in 1 and 2 are linked by on e familiar "syn-syn bridging" carboxylate and two unique "monatomic bridgin g" carboxylates. In 3-6, two "syn-syn bridging" carboxylates and one "monat omic bridging" carboxylate connect two copper(II) ions. Complexes 2 acid 3 are geometrically isometric with each other. Magnetic susceptibility data f or 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 ran ging from -5 to -13 cm(-1), whereas a ferromagnetic coupling is operative i n 3 with a 2J value of 9 cm(-1).