Multinuclear magnetic resonance study of organometallic substituted enamines—stereochemical dependence of vicinal 119Sn–15N spin–spin couplings

✍ Scribed by Ēriks Kupče; Bernd Wrackmeyer; Edmunds Lukevics

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 404 KB
• Volume: 29
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260290507

✦ Synopsis

Abstract

^1^H, ^13^C, ^15^N, ^29^Si and ^119^Sn NMR data (chemical shifts and coupling constants) are reported for the organometallic substituted enamines Me~3~Sn(Me~3~M)CC(NEt~2~)CH~2~OMe [M = Sn (1), Ge (2), Si (3)], of which 2 and 3 are obtained as a mixture of E and Z isomers, and (Me~3~Sn)~2~CC(NEt~2~)CCNEt~2~. Since there is no inverse linear relationship between δ^13^C(MC) and δ^15^N, NC(pp)π interactions must be regarded as being very weak. All vicinal coupling constants, ^3^J(^119^Sn^13^C), ^3^J(^119^Sn^15^N) and ^3^J(^29^Si^15^N), across the CC double bond show the expected stereochemical dependence, with | ^3^J~trans~ | > | ^3^J~cis~ |. To our knowledge, long‐range couplings of this type, involving ^15^N, are reported for the first time. The magnitude of | ^3^J(^119^Sn^15^N)~trans~ | exceeds the magnitude of | ^1^J(^119^Sn^15^N) | in most trimethyltin amides. A relationship between the magnitude of | ^3^J(^119^Sn^15^N) | and the orientation of the nitrogen lone electron pair is proposed.