Molecular spectral analysis and crystal structure of the 4-aminopyridinium tetrachloropalladate(II) complex salt

The aromatic character, distortion and stabilization of the imino-form as a result of protonation of 4-aminopyridine was proved by IR-, UV- and H-1 NMR-spectral analysis of the 4-aminopyridinium tetrachloropalladate(II) complex salt. In particular, linear-dichroic IR-spectroscopy coupled with the orientation technique of solid samples as a liquid crystal suspension was applied for identification of the IR-bands, characteristic for the structural fragments of the discussed imino-isomer. The spectral results obtained were compared and confirmed by a single crystal X-ray study of the used model system. It is formed by a discrete PdCl42- anion and two N-py protonated C5H7N2+ cations. The Pd(II) ion is square planar coordinated with four Cl- ligands. (c) 2005 Elsevier Ltd. All rights reserved.