Thermodynamic study of dinuclear adducts between copper(II) Salen-type complexes and organotin(IV) chlorides in acetonitrile

Abstract

Adduct formation between R₂SnCl₂ (R = methyl and phenyl) and PhSnCl₃ as acceptors and Cu(II) complexes of tetradentate Schiff-base ligands [CuL], where L = [Salen, bis(salicylaldehyde)ethylenediimine], [3-MeOSalen, N,N′-bis(3-methoxysalicylaldehyde)ethylenediimine], [5-MeOSalen, N,N′-bis(5-methoxysalicylaldehyde)ethylenediimine], [5-BrSalen, N,N′-bis(5-bromosalicylaldehyde)ethylenediimine], [salpn, N,N′-bis(salicylaldehyde)1,3-propanediimine], [Salophen, bis(salicylaldehyde)phenylenediimine], [3-MeOSalophen, N,N′-bis(3-methoxysalicylaldehyde)phenylenediimine], and [5-MeOSalophen, N,N′-bis(5-methoxysalicylaldehyde)phenylenediimine], as donors have been investigated in acetonitrile by UV-Vis spectrophotometric analysis. The formation constants and thermodynamic free energies were measured using UV-Vis titration for 1 : 1 adduct formation at various temperatures (T = 293–313 K). The trend of adduct formation for copper Schiff-base complexes with a given tin acceptor decreases as follows: ; The trend of the reaction of R _n SnCl_{4− n} acceptors toward a given copper Schiff-base complex is PhSnCl₃ > Ph₂SnCl₂ > Me₂SnCl₂. The reactivity of PhSnCl₃ toward Cu(Salen), Cu(Salpn), and Cu(Salophen) increases with increasing temperature.

Keywords:

• Copper
• Schiff base
• Organotin chloride
• Formation constants
• Adduct formation

Acknowledgements

We are grateful to Kurdistan University Research Council for their financial support. Thanks are also given to Prof. Mozaffar Asadi, Dr Khosrow Aein Jamshid, Dr Sajjad Mohbbi, and Islam Abroshan.