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Speciation 98: Abstracts
I.O.Fritsky1, A.Karaczyn2, H.Kozlowski2, E.V.Prisyazhnaya1, and V.Kalibabchuk3
1 Department of Chemistry, Shevchenko University,
Kiev 252033, Ukraine;
2 Faculty of Chemistry, University of Wroclaw,
50383 Wroclaw, Poland;
3 Department of Chemistry, National Medical
University, 252004 Kiev, Ukraine
Short intramolecular H-bond =N-O-H . . . O-N= is an important factor in chemistry of oximes regulating the co-ordination mode and the subtle structural features of the metal oxime complexes. We report herein the study of influence of short intramolecular H-bonds on the co-ordination properties of new family of open chain ligand containing adjacent oxime and amide groups - N,N'-bis(2-hydroxyiminopropionyl)-1,2-diaminoethane (H2pen), 1,3-diaminopro-pane (H2pap), 1,3-diaminobutane (H2pab). The complex formation of H2pap with Cu2+ and Ni2+ ions was studies in aqueous solution by potentiometric, spectrophotometric and EPR methods. The species MH-1L and MH-2L were found as dominating upon wide range of pH (4.5 and higher) both in Cu2+ and Ni2+ systems with H2pap (Fig.1,2). The first of them contain the short intramolecular H-bond (Fig.3) which is observed in the crystal structures of three complexes. It can be easily remove by increasing of pH or on interaction with transition metal salts or co-ordinatively unsaturated complexes (e.g., Cu(dipy)Cl2) even at pH < 7. In the Cu - H2pap solution another one species was detected (CuHL) dominating upon pH range of 3.5-4.5, and the dimeric complex [Cu(Hpab)]2(ClO4)2 . 4H2O containing the short H-bonds was crystallised at this pH.
In the species with pseudomacrocyclic co-ordination the short H-bonds play no important role because this mode is mostly stabilised by the presence of three fused chelate rings. At the same time, formation of dimeric metallamacrocyclic complexes is evidently connected with self-assembly occurring due to formation of the short H-bonds.
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