EFFECT OF HYDROGEN-BONDING ON COORDINATION IN NOBENZOATO-O)DI(1,3-DIAMINOPROPANE-N,N')COPPER(II) (Z = 2, 3 OR 4) COMPLEX UNITS

The crystal structures of the series of compounds containing the di (Z -aminobenzoato-O) di(1,3-diaminopropane-N,N')copper(II) (Z = 2, 3 or 4 ) coordination units were determined by single-crystal X-ray methods. In the ortho-and meta-aminobenzoate analogues the structures are compo sed of monomeric complex units, where a copper(II) cation is located a t a centre of symmetry and the chelate rings display a chair conformat ion. The benzoate anions in the axial positions are coordinated via on e oxygen only. In the para-aminobenzoate analogue the complex units ar e similar, but there are two additional crystal water molecules in the asymmetric unit. The main differences between the three coordination units are seen in the bite angle of a chelate ring and the declination value of a benzoate anion. The differences are likely due to variatio n in the participation of an amine group of a chelate ring and a carbo xylate group of a benzoate anion to form a hydrogen bonding network. I ntramolecular hydrogen bonding seems to be correlated with inclination of a benzoate anion. Small inclination and absolute declination value s for a benzoate anion seem to be related with bifurcated intramolecul ar hydrogen bonding and narrowing of a bite angle N-Cu-N. The hydrogen bonding to the coordinated oxygen atom changes its hybridisation from approximate sp(2) towards sp(3). The existence of hydrogen bonding is supported by IR spectra. The crystallographic data are as follows (tn : 1,3-diaminopropane; bzO: a benzoate anion): [Cutn(2)(2NH(2)bzO)(2)], C20H32CuN6O4, monoclinic, space group P2(1)/a No. 14, a=10.513(2), b= 9.1789(12), c=12.126(2) Angstrom, beta=99.82(2)degrees, V=1153.0(4) An gstrom(3); [Cutn(2)(3NH(2)bzO)(2)], C20H32CuN6O4, monoclinic, space gr oup P2(1)/n No.14, a=6.7128(12), b=16.503(4), c=10.268(2) Angstrom, be ta=92.022(15)degrees, V=1136.8(4) Angstrom(3); [Cutn(2)(4NH(2)bzO)(2)] . 2H(2)O, C20H36CuN6O6, monoclinic, space group P2(1)/n No.14, a=9.484 (2), b=8.938(2), c=16.301(3) Angstrom, beta=103.910(14)degrees, V=1334 .6(5) Angstrom(3). (C) 1998 Elsevier Science S.A.