13C, 15N, 29Si and 31P NMR study of N-trimethylsilylaminophosphorus compounds: Sign determination of coupling constants and application of Hahn-echo extended pulse sequences

✍ Scribed by Bernd Wrackmeyer; Ēriks Kupče; Gerald Kehr; Jürgen Schiller

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 618 KB
• Volume: 30
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260300407

✦ Synopsis

Abstract

N‐Trimethylsilylaminophosphorus compounds containing phosphorus in different oxidation states [P(III) and P(V)] and with different coordination numbers (2, 3 or 4) were studied by ^13^C, ^14^N, ^29^Si and ^31^P NMR, using a variety of one‐ and two‐dimensional (2D) techniques, including Hahn‐echo extended (HEED) pulse sequences. These techniques were demonstrated by the determination of the signs of all coupling constants involving the ^1^H, ^13^C, ^15^N, ^29^Si and ^31^P nuclei in bis(trimethylsilyl)aminodimethylphosphane (1). Appropriate experiments, including inverse 2D ^1^H{^15^N} correlations, were performed for the other compounds in order to determine the signs of the coupling constants. A geometric dependence of ^2^J(^31^P, N, ^29^Si) was proved for bis(trimethylsilyl)amino(tert‐butyl)chlorophosphane (2c), where large negative ^2^J(^31^P,^29^Si) and a small positive ^2^J(^31^P,^29^Si) values, indicate syn and anti orientations, respectively, of the NSi bond relative to the phosphorus lone pair of electrons. The HEED pulse sequences allow the rapid determination of isotope‐induced shifts, ^1^δ^15/14^N(^31^P), as shown for 1, derivatives of 1 and 2c.