A Pyridine‐Stabilized N‐Phosphinoamidinato N‐Heterocyclic Carbene‐Diboravinyl Cation: Boron Analogue of Vinyl Cation

• Published in: Angewandte Chemie International Edition Vol. 61; no. 46; pp. e202212842 - n/a
• Main Authors: Fan, Jun, Chia, Pei‐Ting, Zhang, Zheng‐Feng, Yang, Ming‐Chung, Su, Ming‐Der, So, Cheuk‐Wai
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 14.11.2022
• Edition: International ed. in English
• Subjects: Boron; Carbenes; Cations; Computer applications; Diborene; Pyridines; Pyridinium; Small Molecule Activation; Vinyl Cation
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202212842

A boron analogue of vinyl cation, pyridine‐stabilized N‐phosphinoamidinato N‐heterocyclic carbene (NHC)‐diboravinyl cation 2+, was synthesized by displacement of bromide in diborene 1 with excess pyridine. Experimental and computational studies showed that the positive charge is mainly at the B−B skeleton with delocalization to the pyridine ligand. One of the main modes of reactivity is through the B=B double bond alongside activation of the pyridine substituent, where the Bpyridine center is the predominant nucleophilic center and the predominant electrophilic center is either the activated pyridine para position or the BNHC center, illustrating the presence of diborene cation A, borylene‐borenium cation B and diborene‐pyridinium cation C resonance structures in cation 2+. A pyridine‐stabilized N‐phosphinoamidinato N‐heterocyclic carbene‐diboravinyl cation was obtained through the displacement reaction of the bromide substituent on a diborene derivative using pyridine. This newly formed species was shown to be a boron analogue of the vinyl cation which could be used for the activation of small molecules.