Synthesis and characterization of diorganotin(IV) complexes of tridentate Schiff bases: crystal structure of [N-(3-hydroxypyridine-2-yl)-5-chlorosalicylideneiminato]dimethyltin(IV)

Abstract

Some five-coordinated dimethyltin(IV) complexes of the type Me2SnL (where L is the anion of a bifunctional tridentate Schiff base) were synthesized. These Schiff bases are N-(3-hydroxypyridine-2-yl)-3-methoxysalicylideneimine, HOC6H3OCH3CH=NC5H3NOH (1), N-(3-hydroxypyridine-2-yl)-3-ethoxysalicylideneimine, HOC6H3OC2H5CH=NC5H3NOH (2), N-(3-hydroxypyridine-2-yl)-5-chlorosalicylideneimine, HOC6H3ClCH=NC5H3NOH (3), and N-(3-hydroxypyridine-2-yl)-3-methoxy-5-bromosalicylideneimine, HOC6H2OCH3BrCH=NC5H3NOH (4). Dimethyltin(IV) complex of 3 (3a) was characterized by single crystal X-ray diffraction method and a coordination geometry that is nearly halfway between trigonal–bipyramidal and square pyramidal arrangement was found. Dimethyltin complexes of (1), (2), and (4) were also prepared and characterized by the comparison of their elemental analysis and 1H-NMR-, IR-, UV- and mass spectral data with those of (3a). For example, in the 1H-NMR spectra, the 2J(119Sn-1H) in the Sn-CH3 moiety have values between 80 Hz and 90 Hz, typical of five-coordinated tin species. By using these values in Lockart’s Equations, H3C–Sn–CH3 angles in the complexes were estimated to lie between 130° and 145°. X-ray diffraction value for 3a, confirms this estimate within 3.4% relative deviation (129.7° exp. Vs. 134.9° estimate).