Completing the Series of Boron-nucleophilic Cyanoborates: Boryl Anions of Type NHC-B(CN)

Overview

Journal Chem Sci

Publisher Royal Society of Chemistry

Specialty Chemistry

Date 2017 Oct 10

PMID 28989661

Citations 6

Authors

Richard Boser

Lisa C Haufe

Matthias Freytag

Peter G Jones

Gerald Horner

Rene Frank

Affiliations

Soon will be listed here.

Abstract

Since the first seminal report of boron-centred nucleophiles, the area of boryl anions has developed only sporadically and requires further systematisation. The boryl anions of type NHC-B(CN) (NHC = N-heterocyclic carbene) described herein complete a consistent series with the known anions cAAC-B(CN) [cAAC = cyclic(alkyl)(amino)carbene] and B(CN). A novel approach towards NHC-stabilised cyanoboranes based on alkylthio-cyano exchange at boron is presented, and in contrast to other methods affords the products in better purity and yield. Reduction of suitable NHC-dicyanoboranes gave two unprecedented examples of NHC-B(CN) boryl anions. The latter were shown to react as boron-centred nucleophiles with facile formation of B-E bonds, where E = C, Si, Sn, P, Au. Bonding analysis by DFT calculations suggests a systematic variation of the energy of the boron-centred HOMO depending on the carbene, which in turn can control the nucleophilic character.

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