Nickel(II) salophen-type complexes characterization and their thermodynamic studies with diorganotin(IV) dichlorides in chloroform

Abstract

A u.v.–vis spectrophotometric study of the adduct formation of the nickel(II) Schiff base complexes,([NiL]) where L = [3-methoxysalophen, N,N′-bis(3-methoxysalicylidene)-1,2-phenylenediimine] (1), [4-methoxysalophen, N,N′-bis(4-methoxysalicylidene)-1,2-phenylenediimine] (2), [5-methoxysalophen, N,N′-bis(5-methoxysalicylidene)-1,2-phenylenediimine] (3) and [Salophen, [N,N′-bis(salicylaldehydo)-1,2-phenylenediimine] (4) as donors with R2SnCl2 (R = methyl, phenyl and n-butyl) as acceptors have been investigated in chloroform, as solvent. Adducts have been characterized by 1H, 13C and 119Sn NMR, IR and electronic spectroscopy and CHN elemental microanalysis. The formation constants and the thermodynamic free energies were measured using u.v.–vis spectrophotometry titration for 1:1 adduct formation at various temperatures (T = 278 to 308 K). The trend of the adduct formation of the nickel Schiff base complexes with a given tin acceptor decreases as follows: $$\hbox{Ni}(3,4,5\hbox{-MeOSalophen}) > \hbox{Ni(Salophen)}$$ and $$\hbox{Ni}(4\hbox{-MeOSalophen}) > \hbox{Ni}(3\hbox{-MeOSalophen}) > \hbox{Ni}(5\hbox{-MeOSalophen})$$