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

Paulin Nkolo (1) , Gerard Audran (1) , Paul Bremond (1) , Raphael Bikanga (2) , Sylvain R.A. Marque (1) , Valerie Roubaud (1)

1 ICR - Institut de Chimie Radicalaire
2 LASNSOM - Laboratoire de Substances Naturelles et de Synthèses Organométalliques

Solvent effects in beta-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+center dot O-center dot center dot center dot center dot center dot center dot P+-O- dipole - dipole interaction. In this work, we show that the steric strain in Spiro beta-phosphotylated nitroxides affords the opposite trend for a(p) that is, a(p) increases with increasing solvent properties features. (C) 2017 Elsevier Ltd. All rights reserved.

Keywords: electron-transfer; EPR spectroscopy; esr; mri; Multi-parameter analysis; nitrogen; Nitroxides; parameter; probes; resonance; solvation; Solvent effect; solvent polarity

Domains: Chemical Sciences

Paulin Nkolo, Gerard Audran, Paul Bremond, Raphael Bikanga, Sylvain R.A. Marque, et al.. Hyperfine coupling constants of beta-phosphorylated nitroxides: Subtle interplay between steric strain, hyperconjugation, and dipole-dipole interactions. Tetrahedron, 2017, 73 (23), pp.3188--3201. ⟨10.1016/j.tet.2017.04.027⟩. ⟨hal-01774247⟩