Syntheses and structures of monomeric and dimeric ternary complexes of copper(II) with 2,2′-bipyridyl and carboxylate ligands

The syntheses and crystal structures of Cu(C10H8N2)(C9H7O2)(H2O) (1) and [Cu2(C10H8N2)2(C7H6NO2)3(C7H7NO2)]·Cl·3H2O (2) are described [C10H8N2 = 2,2′-bipyridine (bipy); C9H7O2– = cinnamate anion (cinn–); C7H6NO2– = p-amino benzoate anion (paba–); C7H7NO2 = p-amino benzoic acid (Hpaba)]. Complex (1) contains two molecules in the asymmetric unit: both feature a distorted square-pyramidal CuN2O3 chromophore arising from the coordination of a bidentate bipy ligand, two monodentate cinn– anions and a water molecule to the metal ion. The cation in complex (2) is dimeric with square pyramidal CuN2O3 and CuN3O2 metal coordination polyhedra: each metal ion is coordinated by a bidentate bipy ligand and two bridging paba– anions; the apical coordination site of one is occupied by an O-bonded paba– anion and the other by an N-bonded Hpaba neutral molecule. The cation in (2) is isomeric with the previously reported [Cu2(C10H8N2)2(C7H6NO2)2(C7H7NO2)2]2+ cation, in which both apical Hpaba molecules are N-bonded to their metal ions.