Does hydrohalic acid HX (X = F, Cl) form true N-protonated twisted amide salts? Effects of anions on the ion-pair interactions and on the amide moiety in N-protonated tricyclic twisted amide salts

Abstract

The [BF4]− and [RSO3]− anions interact with N-protonated amide cations through N–H⋯F and N–H⋯O strong hydrogen bonds and hydrohalic acids form very weak N⋯H–X hydrogen bonds.

Chemistry of Bridged Lactams: Recent Developments

“…Several additional studies on non-planar amides have been reported. Computational studies on ion-pair interactions in Kirby’s amide HBF 4 salts [53] and N -protonation of twisted amides by HF and HCl [54] were reported by Panday. Mykhailiuk and co-workers reported selective σ N-C bond scission in strained acyclic amides [55].…”