6533b872fe1ef96bd12d4072

RESEARCH PRODUCT

Diorganotin(IV)-2-mercaptopyrimidine complexes

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The complexes formed between the diorganotin(IV) moieties, R 2 Sn(IV), and the ligand 2-mercaptopyrimidine, (H)SPym, were investigated. Complexes R 2 SnHal(SPym) and R 2 Sn(SPym) 2 [R = Me, i Pr, n Bu, i Bu, t Bu, cyclohexyl(Cy), Ph] were synthesized, and characterized by elemental analysis. In the solid state, chelation of SPym through S and N donors was established by IR spectroscopy, and the nature of the environment of tin centers was investigated by 119 Sn Mossbauer spectroscopy. From the dynamics of 119 Sn nuclei determined by variable-temperature measurements on representative compounds [Me 2 SnCl(SPym) and Cy 2- SnBr(SPym)], as well as by point-charge model treatment of nuclear quadrupole splitting parameters, it was inferred that Me 2 SnCl-(SPym) may assume a trans-Me 2 octahedral coordination geometry around tin in a monodimensional polymer, or a monomeric trigonal-bipyramidal structure (distorted). The latter type of structure was assigned to the other R 2 SnHal(SPym) species, while R 2 Sn(SPym) 2 complexes assume a trans-octahedral, or skew trapezoidal, tin environment. In CHCl 3 -CDCl 3 solutions, monomeric species occur (according to vapor-pressure osmometry), where 1 H and 13 C NMR spectroscopic parameters of SPym indicate the persistence of Sn chelation by S and N donor atoms. The Me 2 SnCl(SPym) species assume trigonal-bipyramidal structures with a chelating SPym ligand, in CDCl 3 and C 2 H 5 OH solutions, according to the coupling constants 1 J( 119 Sn, 13 C), as well as IR and 119 Sn Mossbauer spectroscopic data. 119 Sn NMR parameters fully correspond with data for the homologous complexes with 2-mercaptopyridine.