Three trinuclear copper(II) complexes bridged by μ3-CO32- with different coordination modes

Three trinuclear copper(II) complexes bearing the same mu(3)-CO32- bridge and triangular geometry, {[Cu-3(bpy)(6)(CO3)](ClO4)(4)(CH3OH)(H2O)(2)} (1), {[Cu-3(bpy)(6)(CO3)](ClO4)(4)(C2H5OH)(4)(H2O)(2)} (2), and {[Cu-3(bpy)(6)(CO3)](PF6)(4)(H2O)(2)} (3) (bpy = 2,2'-bipyridine), have been synthesized and structurally characterized. The common [Cu-3(bpy)(6)(CO3)](4+) cationic unit is found in 1-3 but distinguishable coordination is observed for the central CO32- bridge, namely mu(3)-eta(2), eta(2), eta(2) in 1, mu(3)-eta(1), eta(1), eta(1) in 2, and mu(3)-eta(1), eta(1), eta(2) in 3. Five-coordinate trigonal bipyramidal and square pyramidal as well as six-coordinate octahedral structures for the copper(II) centers in 1-3 are observed. The presence of different counterions and solvent is responsible for the variations of coordination spheres of copper(II) and crystal packing modes in 1-3.