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

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: [image omitted] [image omitted]; [image omitted] The trend of the reaction of RnSnCl4-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. [ABSTRACT FROM AUTHOR]