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Chemistry. 2018 May 1. doi: 10.1002/chem.201801620. [Epub ahead of print]

B-Heterocyclic Carbene Arising from Charge Shift: A Computational Verification.

Author information

1
Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, P.R. China.
2
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P.R. China.
3
Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008, USA.

Abstract

1-Borabicyclo[1.1.0]but-2(3)-ene (1BB) is a singlet biradical with two single electrons that can form an ionic resonance structure through a charge shift. The ionic resonance structure is a B-heterocyclic carbene (BHC), which can act as a carbene, Lewis base, or L- and Z-type ligand, to give adducts and complexes. Through a range of quantum methods, four types of stable compounds (A-D) derived from 1BB have been designed. These compounds retain the unique features of 1BB. As a consequence, the structures, stability, and Wiberg bond indices of the Lewis adducts of A-D with Lewis acids (BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , and C13 BH9 ) and CuI , AgI , and AuI complexes have been investigated. Results show that A-D can indeed react as carbenes. Interestingly, compounds A-D, as L-type ligands, can attach to BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , C13 BH9 , and CuCl and form compounds with planar tetracoordinate carbon (ptC), whereas Z-type ligands A-D can bind to AgCl and AuCl to provide complexes with planar tetracoordinate boron (ptB). In addition, the binuclear complexes of ClX(1BB)CuCl (X=Ag, Au) have been studied and A-D behave as both L- and Z-type ligands, in which these complexes contain both ptC and ptB. Thus, a novel method for designing compounds with ptC and ptB is presented. These rationally designed compounds involve the elements of carbene, ptC, ptB, and L- and Z-type ligands, and are expected to be unique and useful in experimental chemistry once they are synthesized.

KEYWORDS:

Lewis acids; ab initio calculations; boron; carbenes; heterocycles

PMID:
29714815
DOI:
10.1002/chem.201801620

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