Solvent effects on the hyperfine coupling constant and barrier to internal rotation for the 2-muoxyprop-2-Yl radical

Abstract

The muon-electron β-hyperfine coupling constant is reported for the 2-muoxyprop-2-yl radical formed by positive muon (μ+) implantation in propan-2-one and aqueous solutions of propan-2-one. Using the technique of muon spin rotation (μSR) spectroscopy the coupling constant was measured over a full temperature range in which the samples were in the liquid state. In all cases, the coupling constants were found to be small, and to show a positive temperature dependence. In the aqueous mixtures the presence of the water produces a slight lowering, at all temperatures, in the coupling constant with respect to the coupling in pure propan-2-one. An interpretation is given which relates the radical structure, to the barrier hindering internal rotation and to solvent interactions.