Application of nonmetallic frustrated cations in the activation of small molecules

Abstract

The concept of nonmetallic frustrated cations has been used in the small molecule activation. The in situ generated ambiphilic phosphinoborinium cation activated phenyl isocyanate, diisopropylcarbodiimide, and acetonitrile under very mild...

Phosphinoborenium cations stabilized by N-heterocyclic carbenes: synthesis, structure, and reactivity

“…1 and 3 were previously utilized by us in the synthesis of transient phosphinoborinium cations in reaction with the lithium salt of weakly coordinating anions. 35,36 Synthetic details, nuclear magnetic resonance spectroscopy (NMR), and X-structural data of 2 are placed in the ESI †. We observed that bromide anion abstraction from R 2 N–(Br)B–PR′ 2 led to the formation of unstable borocations [R 2 N–B–PR′ 2 ] + with a di-coordinate boron center.…”

“…30–34 Recently we have turned our attention to cationic systems with B–P bonds, and have described the reactivity of in situ generated phosphinoborinium cations which have strong tendency to dimerization, and exhibit high reactivity toward ketones, isocyanates, nitriles, and carbodiimides to form cycloaddition products. 35,36 As a next step in the exploration of ambiphilic cationic systems, we decided to synthesize phosphinoborenium cations stabilized by NHCs. These species can be treated as cationic phosphinoboranes, where one R substituent is replaced by an NHC ligand (Chart 1).…”