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: