Homolytic Substitution in Trialkyltin Iodides by Photochemically Generated Iodine Atoms. IV. Evaluation of Solvent Effects on the Electron Donor Acceptor Complexes and the Reactivity of Alkylmetals

Abstract

AbstractThe spectrophotometric properties of the trialkyltiniodide‐iodine charge transfer complexes in solution are found to depend on the nature of the solvent. The correlations of these solvent shifts of the absorption bands with various solvent properties are discussed within the frame of the Onsager model of dielectrics. Thus data like dipole moments and stabilization energies of excited states can be obtained.Furthermore a kinetic study of the reactivity of three trialkyltin iodides with iodine atoms has been made in different solvents. The correlation between the absolute rate constants and the polarity (dielectric constant) of the medium suggests increasing solvation of the activated complex with increasing bulkyness of the alkylsubstituent.The solvent free energy of the initial reactant, the excited CT complex, could be calculated from two independently obtained differences of free energies, i.e. the solvent free energy Esolvent going from the standard solvent to the actual solvents and δΔGsolv,x≠' determined from kinetic experiments at different temperatures.