Synthesis, spectroscopy and structure of diorganotin(IV) Schiff base complexes

Three diorganotin(IV) chelates with a tetradentate Schiff base, H-2 Vanophe n, [H-2 Vanophen = N,N'-1,2-phenylen-bis(3-methoxysalicylideneimine)] of th e type R2Sn(Vanophen) (R = Ph: 1; R = n-Bu: 2; R = Me: 3) have been synthes ized by the reaction of R2SnCl2 (R = Ph, n-Bu, Me) and H-2 Vanophen in the presence of triethylamine in benzene. The complexes have been characterised by IR and NMR spectroscopy and by elemental analysis. The St Sn) values fo r the complexes 1 - 3 are -543.0, -414.2 and -398.2 ppm respectively, indic ating hexacoordinated Sn centers. These have been ascertained by X-ray crys tal structure determinations of 1 and 3. The distances between tin and the two axial carbon atoms in each complex differ not significantly [2.17(1) An gstrom in 1, and 2.100(3) and 2.115(3) Angstrom in 3). The C-Sn-C angles fo r 1 and 3 are 165.9(4)degrees and 159.96(9)degrees, respectively. The solut ion NMR spectra (H-1,C-13, Sn-119) show clearly that the solid state struct ures are retained in solution.