MAGNETOSTRUCTURAL CORRELATION IN DIMERIC COPPER(II) BENZOATES

The structures of six dimeric copper(II) benzoates, (I)-(VI), have been determined. Mo K-alpha radiation was used throughout (lambda = 0.71073 angstrom). Tetrakis(mu-benzoato-O,O')-bis(benzoic acid)dicopper(II), [Cu-(C6H5COO)2(C6H5COOH)]2, (I), M(r) = 855.8, monoclinic, P2(1)/n, a = 15.283 (2), b = 11.716 (2), c = 10.783 (1) angstrom, beta = 91.37 (1)-degrees, V = 1930.2 (5) angstrom3, Z = 2, D(m) = 1.48 (2), D(x) = 1.47 Mg m-3, mu = 1.165 mm-1, F(000) = 876, T = 300 (2) K, R = 0.034 for 2990 observed unique reflections. Tetrakis(mu-benzoato-O,O')-bis(beta-picoline)dicopper(II), [Cu-(C6H5COO)2(C6H7N)]2, (II), M(r) = 797.8, monoclinic, P2(1)/n, a = 17.326 (2), b = 10.554 (1), c = 10.655 (2) angstrom, beta = 95.56 (1)-degrees, V = 1939.2 (4) angstrom3, Z = 2, D(m) = 1.41 (2), D(x) = 1.37 Mg m-3, mu = 1.149 mm-1, F(000) = 820, T = 298 (2) K, R = 0.049 for 2896 reflections. Tetrakis(mu-benzoato-O,O')-bis(4-methylquinoline)dicopper(II), [Cu(C6H5COO)2-(C10H9N)]2, (III), M(r) = 897.9, triclinic, P1BAR, a = 10.684 (3), b = 10.780 (2), c = 10.207 (2) angstrom, a = 92.55 (2), beta = 109.78 (3), gamma = 68.44 (2)-degrees, V = 1024.5 (4) angstrom3, Z = 1, D(m) = 1.44 (2), D(x) = 1.46 Mg m-3, mu = 1.096 mm-1, F(000) = 462, T = 299 (2) K, R = 0.035 for 3168 reflections. Tetrakis(mu-benzoato-O,O')-bis(7-methylquinoline)dicopper(II), [Cu(C6H5COO)2(C10H9N)]2, (IV), M(r) = 897.9, monoclinic, P2(1)/n, a = 18.029 (3), b = 20.427 (2), c = 11.673 (3) angstrom, beta = 97.76 (2)-degrees, V = 4260 (1) angstrom3, Z = 4, D(m) = 1.41 (2), D(x) = 1.40 Mg m-3, mu = 1.054 mm-1, F(000) = 1848, T = 298 (2) K, R = 0.058 for 3850 reflections. Tetrakis(mu-benzoato-O,O')-bis(4,7-dichloroquinoline) dicopper(II), [Cu(C6H5COO)2(C9H5Cl2N)]2, (V), M(r) = 1007.7, triclinic, P1BAR, a = 10.657 (2), b = 11.047 (2), c = 10.640 (2) angstrom, alpha = 97.79 (1), beta = 115.08 (1), gamma = 69.13 (1)-degrees, V = 1059.9 (3) angstrom3, Z = 1, D(m) = 1.58 (2), D(x) = 1.58 Mg m-3, mu = 1.316 mm-1, F(000) = 510, T = 299 (2) K, R = 0.031 for 4087 reflections. Tetrakis(mu-benzoato-O,O')-bis(caffeine)dicopper(II) dicaffeine, [Cu(C6H5COO)2(C8H10N4O2)]2.2C8H10N4O2, (VI), M(r) = 1338.3, monoclinic, P2(1)/n, a = 12.922 (2), b = 22.122 (2), c = 10.898 (1) angstrom, beta = 99.42 (1)-degrees, V = 3073.3 (6) angstrom3, Z = 2, D(m) = 1.51 (2), D(x) = 1.50 Mg m-3, mu = 0.773 mm-1, F(000) = 1436, T= 298 (2) K, R = 0.053 for 5036 reflections. The - 2J values from magnetic susceptibility measurements are in the range 316-350 cm-1. The abnormally small antiferromagnetic interaction of the quinoline adduct, -2J = 267 cm-1, is probably due to the bent structure of the Cu-O-C-O-Cu bridges, which have a mean bending angle of 11.4 (3)-degrees.