Conformational Influence of Dithiocarbazinic Acid Bishydrazone Ligands on the Structure of Zinc(II) Complexes: A Comparative XANES Study

Abstract

(1,2-Ethanediyliden)-bis(S-methylhydrazonecarbodithionate) ligands 1a−g form zinc chelates with [ZnN2S2] units, as shown by means of IR, NMR, XPS, X-ray crystal structure analysis, and Zn and N K-edge XANES. The conformation of ligands 1a−g strongly determines the structure of the corresponding zinc complexes 2a−g. Powder samples of these complexes were studied by Zn K-edge XANES. The Zn K-edge XANES results agree with those of X-ray crystal structure data, when available. A tetrahedral ligand environment was confirmed for only one complex (2a). The other zinc chelates (2b−g) show dimeric structures with square pyramidal complex geometry. With pyridine, five-coordinated zinc complexes 3a−c form, as shown by Zn K-edge XANES in comparison with X-ray crystal structure data. XANES studies afford considerable advantage for obtaining structural information, in particular when crystals of sufficient quality cannot readily be obtained.