Synthesis and characterization of tin complexes [Sn(L)Hal(4)] (L = N-alkyl-(pyridin-2-yl)aldimine; Hal = Cl, Br): A structural study

The reactions of the ligands N-methyl-(pyridin-2-yl)aldimine (a), N-ethyl-(pyridin-2-yl)aldimine (b), and N-benzyl-(pyridin-2-yl)aldimine (c) with SnCl4 and SnBr4 led to the formation of compounds [Sn{(C5H4N) HC=NMe)Cl-4] (1), [Sn{(C5H4N)HC=NMe)Br-4] (2), [Sn{(C5H4N)HC=NEt}Cl-4] (3), [Sn{(C5H4N)HC=NEt}Br-4] (4), [Sn{(C5H4N)HC=NBn}Cl-4] (5), and [Sn{(C5H4N)HC=NBn}Br-4] (6) in good yields. All the compounds were characterized by H-1, C-13{H-1}, and Sn-119{H-1} NMR, vibrational IR-Raman spectroscopy, elemental analyses, and X-ray diffraction analysis. The structural studies confirmed the formation of the respective six-coordinate tin complexes as a result of the chelation of the iminic and pyridinic nitrogen atoms of the ligands towards the tin atom; the Sn-N distances were shortened as the Lewis acid character at the tin atom was increased. In all the molecular structures the tin atom displayed a distorted octahedral local geometry.