NMR of terminal oxygen. 9—17O NMR of the PO ‘double bond’: Phosphine oxides, phosphinates, phosphonates, acylphosphonates and related compounds

✍ Scribed by Hans Dahn; Vien Van Toan; My-Ngoc Ung-Truong

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 772 KB
• Volume: 30
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260301112

✦ Synopsis

Abstract

The ^17^O NMR spectra of phosphorus‐bound oxygen atoms in secondary phosphine oxides (R~2~HPO, 1), alkyl phosphinates [RHP(O)OR′, 2 and R~2~P(O)OR′, 3], dialkyl phosphonates [RP(O)(OR′)~2~, 4], dialkyl acylphosphonates [RCOP(O)(OR′)~2~, 5] and some related compounds were measured. The signals of terminal O appear at high field, only slightly downfield from those of bridge O. Compared with carbonyl O, terminal PO shows lower sensitivity to structural variations, notably to geminal groups (with the exception of Cl and Br), and a very low sensitivity to arene ring substituents. The difference is discussed in terms of π‐bond character; the carbonyl oxygen of RCOP(O)OR′)~2~ is sensitive to variations in structure.