Hyperfine coupling constants of β-phosphorylated nitroxides: Subtle interplay between steric strain, hyperconjugation, and dipole-dipole interactions

Abstract Solvent effects in β-phosphorylated nitroxides show that nitrogen and phosphorus hyperfine coupling constants a N and a P , increase and decrease with increasing polarity, polarizity, and Hydrogen Bond Donor effects of solvents, respectively. In a series of articles, it was shown that the driving interaction controlling the change in a P is the maximization of the N +• —O – … ∙∙∙ + P O – dipole – dipole interaction. In this work, we show that the steric strain in spiro β-phosphorylated nitroxides affords the opposite trend for a P , that is, a P increases with increasing solvent properties features.