CRYSTAL STRUCTURES OF TWO Cu(II) COMPLEXES WITH TETRADENTATE SCHIFF BASE LIGANDS. By T.H. Lu¹, B.H. Chen², W.T. Huang², H.H. Yao2, and J.M. Lo² Department of Physics¹ and Department of Nuclear Science², National Tsing Hua University, Hsinchu, Taiwan 300, ROC

Transition-metal complexes containing tetradentate Schiff base ligand have been extensively studied. The magnetic, electronic and electrochemical properties of these complexes depend markedly on different derivatives of Schiff base ligands. Among bridged Schiff base complexes, the imino nitrogen atoms are bound together with polymethylene chains which, through variation of their length, allow tuning of geometry around the metal centre.(Garnovskii, Nivorozhkin & Minkin, Coord. Chem. Rev., 1993, 126, 1-69) In order to study the effect of polymethylene chains on the structures of Cu(II) complexes, we have prepared and studied the structures of the two Cu(II) complexes which were determined by x-ray diffraction. (A). Cu(II) complex of N,N'-bis-(2-hydroxybenzyl)1,3-diiminopropane, [Cu(C₁₇H₁₆N₂0₂)], Orthorhombic, Pna2₁, a=12.021(1), b=17.9l8(3), c=6.8740(7)Å, R=0.044, wR=0.072 for 2317 observed reflections; (B). Cu(II) complex of N,N'-bis-(2 hydroxybenzyl)1,3-diimino-2,2-dimethylpropane, [Cu(C₁₉H₂₀N₂0₂)], Monoclinic, P2₁/n, a=9.7329(9), b=17.186(2), c=11.338(1)Å, [[beta]]=112.99(1), R=0.064, wR=0.077 for 3998 observed reflections. Both of the two complexes are four coordinated with Cu(II) in distorted tetrahedral geometry with two imines N atoms and two phenol O atoms. The related ethylene diamine analogue, N,N'-bis-(2-hydroxybenzyl)1,2 diiminoethane copper, exhibits a square-planar coordination.(Hall & Waters, J. Chem. Soc., 1960, 2644)