Tin(IV) Derivatives of the Tetradentate Ligand N, N - Bis-(2-Pyridylmethylene)-Ethane-l, 2-Diamine zyxwvutsrqponmlkjihgfedcbaY Jose Roberto da S. Maia a '\ Rafael C. R. Chagas 3 , Vany P. Ferraz b and Maria I. Yoshida b zxvutsrponmlifedcbaVUTRQ a Departamento de QuDmica, CCET / UFV, A v. P. H. Rolfs s/n, Vinosa, MG, 36570-000, Brasil. b Departemente de QuDmica, ICEx / UFMG, Belo Horizonte, MG, 31270-901, Brasil. ABSTRACT A series of organotin(IV) (SnClJMu-x, χ = 1, 2, 3) and SnCL, derivatives of N, N'-bis-(2- pyridylmethylene)-ethane-1, 2-diamine (pmed) have been prepared in 2:1 (M:L) molar ratio in dichloromethane. The SnClPh 3 derivative has afforded an equimolar product in contrast to the other metal precursors. The materials were characterised by infrared, multinuclear ('H, "C, n9 Sn) NMR spectroscopy, thermal analysis (TG, DSC), gel permeation chromatography (GPC) and microanalysis. The spectroscopic methods have given evidence for metal-ligand bond formation through pyridyl and azomethine nitrogen atoms. For the SnClPh 3 derivative a five-fold coordination metal centre has been revealed by 1,9 Sn NMR in CH 2 Cl 2 .in contrast to the SnCl x Ph 4 . x (x = 2, 3, 4) derivatives. In those both six- and seven-fold coordination species have been revealed in DMF. The 119 Sn NMR resulting data suggest that a dynamic process has taken place in solution, leading to a structural rearrangement by auto-association. In addition, the GPC technique has revealed in DMF higher values of weight-average molar mass in comparison to that established by the elemental analysis. However, the molar mass obtained for those compounds does not correspond to polymeric materials, as confirmed by DSC analysis. INTRODUCTION Schiff bases constitute an appealing class of organic compounds to work within the coordination chemistry field /l, 2/. Those materials have been known for more than one hundred years and have an enormous range of applications /3/. The interest of inorganic chemists in this class of compounds is in connection to technological development concerning the usefulness of metal-Schiff base complexes. The expectation of that is unquestionable. For instance, complexes have already been applied in asymmetric catalysis /4/, non-linear optics /5/ as well as in the biological field /6, 7/ presenting a variety of biological activity. This research field has been growing in recent decades. The presence of the metal seems to play an * Author to whom correspondence should be addressed. E-mail: jrsmaia@ufv.br 2 321 Bereitgestellt von | De Gruyter / TCS Angemeldet | 212.87.45.97 Heruntergeladen am | 31.10.12 15:30