Intramolecular Hydrogen Bond Reverting the Solvent Effect on Phosphorus Hyperfine Coupling Constants of β‐Phosphorylated Nitroxides. Issue 23 (9th November 2016)

• Record Type: Journal Article
• Authors: Audran, Gérard; Bosco, Lionel; Brémond, Paul; Butscher, Teddy; Marque, Sylvain R. A.; Viel, Stéphane
• Is Part Of: Chemphyschem. Volume 17:Issue 23(2016)
• Page Start: 3954
• Page End: 3963
• Publication Date: 2016-11-09
• Subjects: EPR spectroscopy -- hydrogen bonds -- multiparameter analysis -- nitroxides -- solvent effect; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201600647
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Recently, we reported a dramatic solvent effect on the phosphorus hyperfine coupling constant a P of β‐phosphorylated six‐membered ring nitroxides, that is, approximately 25 G of difference in a P from 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, a P increases 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, a P decreases 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 a P . Abstract : Solvents affect couplings : In common β‐phosphorylated nitroxides, the hydrogen bond donor property, α, of solvents affords a decrease in phosphorus hyperfine coupling constant a P . In β‐phosphorylated nitroxides exhibiting intramolecular hydrogen bonds (IHBs), the hydrogen bond acceptor property, β, overbalances the hydrogen bond donor property α of solvents and affords an increase in a P .