The β Effect of Silicon in Phenyl Cations

摘要: Irradiation of chloroanisoles, phenols, and N,N-dimethylanilines bearing a trimethylsilyl (TMS) group in the ortho position with respect to chlorine atom caused photoheterolysis Ar−Cl bond formation corresponding ortho-trimethylsilylphenyl cations triplet state. The β effect silicon on these intermediates has been studied by comparing resulting chemistry alcoholic solvents that silicon-free analogues computational analysis (at UB3LYP/6-311+G(2d,p) level MeOH). TMS groups little affect photophysics photocleavage starting phenyl chlorides, while stabilizing cations, both (ca. 4 kcal/mol per group) and, dramatically, singlet state (9 kcal/mol). As result, although are first formed species, intersystem crossing more stable singlets is favored chloroanisoles phenols. Indeed, compounds, solvent addition give aryl ethers (from singlet)...