Synthesis and characterization of binuclear transition metal complexes incorporating the tridentate chelating ligand dimethyl (N,N-dimethylethanolamino)(1-pyrazolyl)gallate: crystal and molecular structure of bis-μ-pyrazolyl-(N(1),N(2))-bis[dimethyl(N,N-dimethylethanolamino)-(1-pyrazolyl)gallato(N(2),O,N)copper(II)]

Details of the synthesis of the tridentate tris chelating ligand dimethyl(N,N-dimethylethanolamino)(1-pyrazolyl)gallate and the preparation and physical properties of the binuclear transition metal complexes incorporating this ligand are given. Crystals of bis-μ-pyrazolyl(N(1),N(2))-bis[dimethyl(N,N-dimethylethanolamino)(1-pyrazolyl)gallato(N(2),O,N)copper(II)] are monoclinic, a = 12.018(2), b = 10.390(1), c = 13.568(3) Å, β = 100.04(6)°, Z = 2, space group P21/c. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.045 and Rw of 0.058 for 2460 reflections with I ≥ 3σ(I). The centrosymmetric binuclear molecule features copper atoms having distorted square pyramidal co-ordination geometry. Three of the basal positions are occupied by the oxygen, pyrazolyl nitrogen, and amino nitrogen atoms of the tridentate tris-chelating ligand. The two remaining sites are occupied by bridging pyrazolyl groups, which provide a basal nitrogen atom to one copper atom and an apical nitrogen atom to the second copper centre. The gallium atoms have distorted tetrahedral coordination geometry. Important bond lengths (corrected for libration) are: Cu—O, 1.981(3), Cu—N(basal), 1.953(3)–2.143(4), Cu—N(apical), 2.173(3), Ga—O, 1.907(3), Ga—N, 1.991(4), and Ga—C, 1.962(7) and 1.977(7) Å.