Dynamic 13C NMR studies on the internal rotation in tetraarylallyl anions

✍ Scribed by H. Bauer; M. Angrick; D. Rewicki

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: English
• Weight: 395 KB
• Volume: 12
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270121105

✦ Synopsis

Abstract

Proton noise decoupled ^13^C NMR spectra of lithium 1,1,3,3‐bis (2,2′‐biphenylylene)propenide and lithium 1,1,3,3‐tetraphenylpropenide have been studied, and complete assignments have been made based on several methods, e.g. ^13^C^13^C coupling constants of selectively labelled compounds and low‐temperature splitting of temperature dependent signals. The barriers to rotation about the partial double bonds of the allyl group have been determined by ^13^C DNMR resulting in the thermodynamic parameters of activation ΔG = 57 kj mol^−1^, ΔH^≠^ = 56.5 kj mol^−1^, ΔS^≠^ = −3J mol^−1^K^−1^ and ΔG = 55.5 kj mol^−1^, ΔH^≠^ = 63 kj mol^−1^, ΔS^≠^ = 26 kJ mol^−1^K^−1^, respectively. The results are discussed, including the hitherto known data about the topomerisation process.