Synthesis and characterisation of four and five coordinate Tin(IV) salophenates

Abstract

Herein are described the synthesis and characterization of the complexes of the formulas R,SnL and R^SnLClj n (where R = Ph. n-Bu. Me and L = (Salophen)H2 = N, N'-o-phenylene bis(salicylideneimine). All of the compounds were characterized by melting points, elemental analyses, molecular weight determinations and spectral (IR, Ή, C and 11 "Sn NMR) studies. The complexation occurs via the oxygen and the imino nitrogen atom. Introduction Despite the fact that salen and salophen ligand complexes of transition metals' have been known for over sixty years, very little has been accomplished with regards to the main group elements. Monomeric group-13 derivatives of salen ligands have appeared in the literature" providing a unique opportunity to examine the formation and reactivity of the group-13 elements in a five-coordinate geometry. However, no work has been carried out on salophen complexes with organotin(IV). Salen ligands give complexes which also hold promises in enantioselective cyclopropanation of styrenes, asymmetric aziridination of olefins, asymmetric Diels-Alder cycloaddition and enantioselective ring opening of epoxides". Generally, the electronic and structural properties of the ligands play an important role in the catalytic properties. This in view of the synthetic and catalytic importance of the ligand and in continuation of our studies on organotin(IV) derivatives', we report here the syntheses and characterization of some new organotin(IV) complexes of N,N'-ophenylene bis(salicylideneimine) Results and Discussion (Salophen)H2 was characterized by IR, Ή NMR spectroscopy and satisfactory microanalyses. The crystal structure of (Salophen)H2 indicates an enoliminic structure. In support of this formulation, a broad resonance in the low field at δ 13.02 PPm is evident in the Ή NMR spectrum which disappears upon exchange with D20. Triorganotin(IV) and diorganotin(IV) derivatives of Ν,Ν'-ο-phenylene bis(salicylideneimine) have been synthesized by the reaction of the corresponding triorganotin(IV) and diorganotin(IV) chlorides with the conjugate base of the ligand (prepared in situ) in 1:1 and 2:1 molar ratios, respectively. (R=Ph, Compd.l; R= n-Bu, Compd.2.) (n=l, R=Me, Compd.3; n=l, R=n-Bu, Compd.4.)