Dynamic NMR as a Nondestructive Method for the Determination of Rates of Dissociation. IX. Rates of Dissociative Reactions of the Coordinated Form of [o-(Diethylaminomethyl)phenyl]halodimethyl(or diphenyl)stannanes

Abstract

The coordinated form of [o-(diethylaminomethyl)phenyl]halodimethyl(or diphenyl)stannanes was found to exhibit dynamic behaviors in their 1H NMR spectra. Examination of a series of halogen compounds by total line shape analysis of the diastereotopic methylene proton signals revealed that, at 10 °C, the rates of dissociation were 11.7, 22.9, 28.6, and 73.3 s−1 for fluoro, chloro, bromo, and iodo compounds, respectively: The results are in conformity with the expectation from the electronegativity of halogens. The relatively small differences in the activation parameters in the whole series may include contribution by solvation energies. The diphenyl compound exhibited fast exchange rates relative to the corresponding dimethyl compound. This was attributed to the steric factor rather than the pπ-dπ interaction.