Synthesis, characterization and thermodynamic studies of complexes of dimethyl, diethyl, and diphenyltin-dione dioxime

The diorganotin(IV) compounds, [[Me.sub.2]Sn[Cl.sub.2]([H.sub.2]L)], [[Et.sub.2]Sn[Cl.sub.2]([H.sub.2]L)] and [[Ph.sub.2]Sn[Cl.sub.2]([H.sub.2]L)] ([H.sub.2]L = (2H)-1,4-benzothiazine-2,3-(4H)-dione dioxime), were synthesized by treating the appropriate diorganotin(IV) dichloride with [H.sub.2]L in anhydrous ethanol. These complexes were characterized by IR, MS, UV-Vis, and ¹H NMR. Thermodynamic studies of the reported complexes have been carried out and their stability were found in the order: [[Me.sub.2]Sn[Cl.sub.2]([H.sub.2]L)] > [[Et.sub.2]Sn[Cl.sub.2]([H.sub.2]L)] > [[Ph.sub.2]Sn[Cl.sub.2]([H.sub.2]L)]. Theoretical calculations at the HF/3-21G* level showed that structures with alkyl groups at axial positions are more stable than their counterparts having alkyl groups at equatorial. KEY WORDS: Diorganotin(IV) dichloride, vic-Dioxime, (2H)-1,4-Benzothiazine-2,3-(4H)-dionedioxime, Thermodynamic studies