engleski

Cu(II)-promoted chemical transformations of 3-substituted 5-(2'-pyridyl)-1, 4-benzodiazepin-2-one derivatives. Crystal structures and spectroscopic characterization of metal complexes

In ethanolic solution of CuCl2.2H2O enantiomerically pure 7-bromo-1, 3-dihydro-3-hydroxymethyl-1-methyl-5-(2'-pyridyl)-2H-1, 4-benzodiazepin-2-one, (+)-1, afforded dichloride adduct 3, [CuCl2(1)], isolated as a racemic compound. The replacement of one chlorine with DMSO gave complex 4, [CuCl(1-H)(DMSO)]. The C(3)-oxygenated product appeared as a racemic N, N, O-tridentate ligand in a square-pyramidal complex 5. A product of oxidative ring contraction of (+)-1 yielded 6-bromo-1, 4-dihydro-4-ethoxy-1-methyl-4-(2'-pyridyl)-1, 3-quinazoline, which was found as an N, N-bidentate ligand in the tetrahedral complex 6. 3-Acetoxymethyl-7-bromo-1, 3-dihydro-1-methyl- 5-(2'-pyridyl)-2H-1, 4-benzodiazepin-2-one, (ą)-2, afforded the square-pyramidal complex 7, [CuCl2(2)]. In this complex the lactam oxygen atom of a neighbouring molecule completes a five-fold coordination forming an infinite chain of connected polyhedra in the crystal. A product of oxidative ring contraction of 2 leads to 6-bromo-1, 4-dihydro-4-hydroxy-1-methyl-4-(2'pyridyl)-1, 3-quinazoline, which acts as an N, N-bidentate ligand in the centrosymmetric binuclear five-coordinated Cu(II)-complex 8. In this complex di-ľ-chloro bridges are asymmetrical: one is of an appical coordination site [Cu-Cl, 2.820 (7) Ĺ], whereas the other one is of an equatorial site [Cu-Cl, 2.252 (5) Ĺ]. The complexes are characterised by IR spectra and X-ray structure analysis. Mechanisms of racemization, oxygenation and ring contraction are discussed.

5-pyridyl-1; 4-benzodiazepin-2-one ligands; 1; 4-dihydro-1; 3-quinazoline ligands; racemization; oxygenation; ring contraction; Cu(II)-four- and -five-coordinated complexes; IR spectroscopy; X-ray structure

nije evidentirano