title: Intramolecular Hydrogen Bond Reverting the Solvent Effect on Phosphorus Hyperfine Coupling Constants of β-Phosphorylated Nitroxides.
abstract: Recently, we reported a dramatic solvent effect on the phosphorus hyperfine coupling constant aPof β-phosphorylated six-membered ring nitroxides, that is, approximately 25 G of difference in aPfrom n-hexane to water (Org. Biomol. Chem. 2016, 14, -1228-1292). In this article, we report on the effect of intramolecular hydrogen bonding (IHB) in three nitroxides exhibiting IHB between the hydroxyl and diethylphosphoryl groups and one exhibiting IHB between the hydroxyl group and the nitroxyl moiety. It is observed that for the first three nitroxides, aPincreases with increasing polarity/polarizability and hydrogen bond donor (HBD) properties of the solvent (π* and α, respectively)-in sharp contrast to the data reported in the literature-and for the last nitroxide, aPdecreases with π* and α. In fact, the occurrence of IHB induces a large strain, its suppression by hydrogen bond acceptor (HBA) solvents affords an increase in aP.
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Audran
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Bosco
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Brémond
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.
authors.forename: Teddy
authors.initials: T
authors.lastname: Butscher
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.|N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, Pr. Lavrentjeva 9, 630090, Novosibirsk, Russia.
authors.forename: Sylvain R A
authors.initials: SR
authors.lastname: Marque
authors.affiliation: Aix Marseille Univ, CNRS, ICR, UMR 7273 case 541, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.|Institut Universitaire de France, 75000, Paris, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Viel
keywords: EPR spectroscopy; hydrogen bonds; multiparameter analysis; nitroxides; solvent effect