engleski

Copper(II) coordination chemistry of C(3)-substituted 1, 4-benzodiazepin-2-ones

The synthesis, some spectroscopic properties and X-ray structure analysis of the new copper(II)dichloride complexes of 3-hydroxymethyl- (1), and 3-acetoxymethyl- (2) derivatives of 7-bromo-1, 3-dihydro-1-methyl-2H-1, 4-benzodiazepin-2-one are presented. 1, 4-Benzodiazepine-2-one derivatives are well known CNS active compounds. Well documented properties of nitrogen ligands to form metal complexes possessing biological activity even higher than the free ligands, prompted us to prepare copper-complexes of 1 and 2. During the crystal growth of complexes, unexpected chemical transformations occurred. Mechanisms of these chemical transformations will be discussed. The complexes were prepared by reaction of copper(II)chloride dihydrate and benzodiazepine ligands in 1:1 metal to ligand ratios in two different solvents: ligand 1 in absolute ethanol and ligand 2 in a mixture of dichloromethane and ethanol. In the first case two kinds of crystalline complexes were obtained: complex A (green) and complex B (black). X-ray structure analysis has shown that green complex (monoclinic, P21/n ; a= 8.48Ĺ ; b =15.05Ĺ ; c=17.47Ĺ ; b =91.64°) (Fig. 1) contains the rearranged benzodiazepine ligand as the 3-hydroxy substituted derivative of 1. The Cu(II)complex exhibits five-fold coordination in the shape of a square pyramid. The crystal structure analysis of the black complex B (Fig. 2) has shown an unprecedented transformation of benzodiazepine ligand to quinazole, whith square-planar coordiantion of Cu(II) (monoclinic, P21/n ; a=10.073 Ĺ, b=13.027 Ĺ, c=14.020 Ĺ, b=105.71°) The 3-acetoxymethyl-substituted ligand (derivative 2) did not exhibit chemical transformation upon metal complexation. In the complex C (monoclinic, P21/n ; a=10.815 Ĺ, b=9.072 Ĺ, c=19.985 Ĺ, b=98.64°) Cu(II) is coordinated by two nitrogen atoms and two chlorine atoms (Fig. 3). The five-fold coordination is completed by oxygen of a carbonyl group from the neighbouring ligand molecule. By this bridging an infinite chain is formed.

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