Model studies of trialkyltin–protein interactions: ¹³C NMR analysis of solution equilibria of the complex between trimethyltin and methyl N‐benzoyl‐l‐leucyl‐l‐histidinate

Abstract 13 C NMR spectra for the 1:1 complex between methyl N ‐benzoyl‐l‐leucyl‐l‐histidinate and the trimethyltin moiety in d‐chloroform (CDC1 3 ), d 4 ‐methanol (CD 3 OD) dimethyl sulphoxide (DMSO) and d 6 ‐DMSO/H 2 O solvents are reported, and contrasted with those for the free ligand. The spectra are interpreted in terms of a variety of solution equilibria illustrating the nature of the interaction between the trimethyltin species and primarily the imidazole ring of the histidine residue. Evidence for the preferential stability of pentacoordinate solution structures about tin is presented.