Interactions of d(10) metal ions with hippuric acid and cytosine. X-ray structure of the first cadmium (II)-amino acid derivative-nucleobase ternary compound

The interactions of Zn(II), Cd(II) and Hg(II) with hippuric acid (hipH) wer e studied and several novel compounds were synthesized and studied by NMR. Some new metal-hippuric-cytosine ternary compounds were formed and the stru cture of the [Cd(hip)(2)(cyt)(H2O)](2) ternary complex resolved. Each cadmi um (II) atom has a distorted trigonal bipyramid coordination which is linke d to a water molecule, a cytosine via N(3), a carboxylic oxygen atom of a h ippurate moiety and two bridging dicoordinated hippurates bound through the carboxylic oxygen atoms. To these five main bonds, two longer ancillary in teractions can be observed: the second oxygen of the monocoordinated hippur ate group and the carboxylic oxygen of the cytosine ligand. The compound is stabilized by an intramolecular stacking between the benzene and cytosine rings and by the hydrogen bonds between the coordinated water molecules and the ligands. This is, to our knowledge, the first structure of a cadmium-a mino acid derivative-natural nucleobase compound described so far. (C) 2001 Elsevier Science B.V. All rights reserved.