PLANAR OR TETRAHEDRAL COORDINATION IN COPPER(II) COMPLEXES INDUCED BYBROMO SUBSTITUTION

The diffraction study of bis(5-bromo-N-m-tolylsalicylaldiminate)copper (II) shows the copper atom in a centrosymmetric position and the two l igands displayed trans to each other in a planar environment. Two addi tional weak interactions due to Br atoms (Jahn-Teller effect) of neigh boring units complete the coordination sphere, Cu-Br = 3.662(2) Angstr om, so that the complex is formally a polynuclear two-dimensional spec ies. On the contrary, is(3,5-dibromo-N-p-tolylsalicylaldinate)copper(I I) is mononuclear and shows only the two ligands coordinated and the g eometry is distorted 'tetrahedral'. The distortion is due to intramole cular repulsion interactions. Electronic spectra of these two compound s show a single asymmetric band at 700 nm for the former, and two band s located at 650 and 850 nm for the latter. Both compounds are monocli nic, space group P2(1)/c with a=9.919(2) Angstrom, b=10.965(2) Angstro m, c=12.283(2) Angstrom, beta=105.88(1)degrees, Z=2 for the former, an d a=13.290(2) Angstrom, b=12.195(2) Angstrom, c=17.891(2) Angstrom, be ta=105.38(1)degrees, Z=4 for the latter. (C) 1998 Elsevier Science S.A .