Investigations on Novel 1,3‐Diazetidine Based Four‐Membered N‐Heterocyclic Carbenes

• Published in: European journal of inorganic chemistry Vol. 26; no. 13
• Main Authors: Karl, Leonard, Meisner, Jan, Ganter, Christian
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 02.05.2023; Wiley Subscription Services, Inc
• Subjects: azetidines; Carbenes; Carbonyls; Chemistry; Chemistry, Inorganic & Nuclear; density functional calculations; Density functional theory; Dimerization; Inorganic chemistry; N-heterocyclic carbenes; Physical Sciences; Science & Technology; Spectrometry; density functional calculations; COMPLEXES; carbenes; dimerization; ATOMS; CATALYST; FORMAMIDINES; azetidines; N-heterocyclic carbenes; CATIONS
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202300022

Attempts towards the synthesis of two novel four‐membered 1,3‐diazetidine based N‐heterocyclic carbenes (NHCs) containing an organic backbone with a carbonyl functionality were undertaken. These carbenes cannot be isolated but the respective carbene dimers are obtained in quantitative yield which undergo a degradation and rearrangement sequence upon thermal exposure. Some of the species involved in these thermal reactions could be isolated and characterized, others were observed by mass spectrometric experiments. Ab initio and density functional theory (DFT) calculations provide a mechanistic rationale for the experimental observations. Since dimerization is strongly favored, classic carbene trapping reactions remain a goal to achieve. Novel four‐membered NHCs containing a carbamide backbone rapidly form the respective carbene dimers in quantitative yield. Thermal fragmentations are rationalized with the help of quantum chemical calculations.