Synthesis, characterization and thermal studies of dinuclear adducts of diorganotin(IV) dichlorides with nickel(II) Schiff-base complexes in chloroform

Abstract

The formation constants and free energies for the interaction of R₂SnCl₂ (R = methyl, n-butyl, phenyl) as acceptors, with nickel Schiff-base complexes, ([NiL]) where L = Salen [N,N′-bis(salicylaldehydo)ethylenediimine] (1), 7,7′-Me₂Salen [N,N′-bis(2-hydroxyacetophenone) ethylenediimine] (2), Salpn [N,N′-bis(salicylaldehydo)-1,3-propanediimine] (3), Salophen [N,N′-bis(salicylaldehydo)-1,2-phenylenediimine] (4) as donors and also the interaction of Ph₂SnCl₂ with [NiL′], where L′ = [5-methoxysalen, N,N′-bis(5-methoxysalicylidene)ethylenediimine] (5), [5-methoxysalophen, N,N′-bis(5-methoxysalicylidene)-1,2-phenylenediimine] (6) and [5-chlorosalen, N,N′-bis(5-chlorosalicylidene)ethylenediimine] (7) in chloroform have been studied. The complexes and adducts have been characterized by ¹H, ¹³C and ¹¹⁹Sn NMR, IR and electronic spectroscopy and elemental microanalysis. Formation constants and thermodynamic free energies were measured using UV–Vis spectrophotometric titration for 1:1 adducts. Data refinement was carried out with SQUAD 84 program. The trend of adduct formation for the nickel Schiff-base complexes with a given tin acceptor decreases:

The trend for R₂SnCl₂ acceptors toward a given nickel Schiff-base complex is:

Keywords:

• Nickel
• Schiff base
• Diorganotin dichloride
• Formation constants
• Adduct formation
• Thermodynamic

Acknowledgement

We are grateful to Shiraz University Research Council for their financial support.