Thermodynamics of metalligand bond formation: XXXIV. Lewis acidity of organotin iodides

Abstract

Thermodynamic data have been obtained by calorimetric titration in benzene solution at 30°C for reactions of N-donor Lewis bases with tin tetraiodide, dimethyl-, diphenyl- and dibenzyl-tin iodides, triphenyl- and tribenzyl-tin iodides, and di- and tri-benzyltin chlorides. The triorganotin iodides form 1:1 adducts of low stability with pyridine or 4-methylpyridine, but do not react with 2,2′-bipyridine or 1,10-phenanthroline. The other compounds form 1:1 adducts with the bidentate bases and both 1:1 and 1:2 adducts with unidentate bases, always of lower stability than adducts with corresponding chlorides. Where addition of successive molecules of base occurs it is found that: K 1 < K 2 and K 1Δ H 1 < K 2Δ H 2.