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

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-hydroxypyridine2-yl)-5-chlorosalicylideneimine, HOC6H3ClCH=NC5H3 NOH (3), and N-(3-hydroxypyridine-2-yl)-3-methoxy-5-bromosalicylideneimine, HOC6H2OCH3BrCH=NC5H3 NOH (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 H-1-NMR-, IR-, UV- and mass spectral data with those of(3a). For example, in the H-1-NMR spectra, the (2)J(Sn-119-H-1) 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 degrees and 145 degrees. X-ray diffraction value for 3a, confirms this estimate within 3.4% relative deviation (129.7 degrees exp. Vs. 134.9 degrees estimate).