Application of Hahn-echo extended pulse sequences to phosphorus–nitrogen compounds. Determination of coupling signs and detection of 15N31P15N isotopomers in natural abundance

✍ Scribed by Bernd Wrackmeyer; Christian Köhler; Eriks Kupče

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 398 KB
• Volume: 31
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260310815

✦ Synopsis

Abstract

Hahn‐echo extended (HEED) pulse sequences in one‐ and two‐dimensional experiments were successfully applied to phosphorus–nitrogen compounds with two PN bonds {2‐chloro‐1,3‐dimethyl‐1,3,2‐diazaphospholidine (1), 2‐tert‐butyl‐1,3‐dimethyl‐1,3,2‐dizaphospholidine (2), bis(diethylamino)chlorophosphane (3) and bis(diethylamino)phosphenium cation (4; counterion [AlCl~4~]^−^)}. In the case of 2, the ^31^P resonance signal was detected as a sharp triplet for the ^15^N^31^P^15^N isotopomer in natural abundance: the secondary isotope effect on the coupling constant ^1^J(^31^P^15^N) in ^14^N^31^P^15^N and ^15^N^31^P^15^N isotopomers is < 0.05 Hz; the isotope‐induced shifts ^1^Δ ^15/14^N(^31^P) are additive. The value of ^1^Δ ^15/14^N(^31^P) in the phosphenium cation 4 is markedly more negative than that in its precursor 3 or other aminophosphanes. For 2, the absolute signs of the coupling constants ^2^J(^15^N ^1^H) ( < 0), all ^3^J(^31^P^1^H) ( > 0), ^1^J(^31^PC^13^C) ( < 0), ^2^J(^31^PC^13^C) ( > 0), ^2^J(^31^PN ^13^C~CH~~3~) ( > 0) and ^2^J(^31^PNC~CH~~2~) ( < 0) were determined using ^1^H detected 2D inverse pseudo triple resonance ^1^H{(^13^C)^31^P} experiments and 2D ^13^C^1^H, ^15^N^1^H and ^31^P^1^H heteronuclear shift correlations.