A Pyridine‐StabilizedN‐PhosphinoamidinatoN‐Heterocyclic Carbene‐Diboravinyl Cation: Boron Analogue of Vinyl Cation

Abstract

A boron analogue of vinyl cation, pyridinestabilized 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 BÀ 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 B pyridine center is the predominant nucleophilic center and the predominant electrophilic center is either the activated pyridine para position or the B NHC center, illustrating the presence of diborene cation A, borylene-borenium cation B and diborenepyridinium cation C resonance structures in cation 2 + .