Thermal analysis of isostructural solvate complexes of Co(II) and Ni(II)

Abstract

The decomposition patterns of isostructural compounds are usually very similair, in some cases identical.1,2 Isostructural compounds with different thermal decomposition patterns3 are very rare. Accordingly our aim was to investigate the thermal behavior of isostructural complexes of Co(II) and Ni(II) with the same organic ligand. In one pair of these complexes beside the tridentate N,N’–bis(4-acetyl-5-methylpyrazole-3-yl)formamidine (ampf) ligand, two methanol molecules and a nitrato group is coordinated to the metal cation (Co, Ni). The other nitrate ion is in the outher coordination sphere of complexes. In the other pair of coordination compounds three water molecules are bonded to the metal ions. One water molecule and two perchlorate ions are in the outer coordination sphere of complexes. We observed similarities between the desolvation mechanisms of the two complexes of Co(II) and of Ni(II), too (see figure). The solvent molecules depart both of Co(II) compounds in two well separated steps. Unlike this the desolvation processes of Ni(II) complexes are overlapped. We can conclude that the patterns of desolvation of these complexes are determined by the metal ions. Fig. DTG curves of theisostructural complexes of Co(II) and Ni(II) References 1. Z. Rzączyńska, M. Woźniak, W. Wołodkiewicz, A. Ostasz, S. Pikus, Journal of Thermal Analysis and Calorimetry, 88 (2007) 871–876 2. S. A. Gromilov, E. A. Shusharina, P. E. Plyusnin, S. P. Khranenko, Journal of Structural Chemistry 51 (2010) 773-777 3. R. Łyszczek, Applied Surface Science 257 (2010) 1736–1739