1
|
Zhang L, Cao Z. Formation and reactivity of NHC-boryl radicals: insight into substituent effect from theoretical calculations. Phys Chem Chem Phys 2023; 25:12072-12080. [PMID: 37093024 DOI: 10.1039/d3cp01037f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Substituent modification effects of N-heterocyclic carbene (NHC) boranes on their hydrogen atom abstraction (HAA) reactions and the chemical reactivities of corresponding NHC-boryl radicals have been investigated by density functional theory calculations. The substituent modification of NHC-boranes may notably affect the HAA reaction, both kinetically and thermodynamically, and shows remarkable substitution position dependence. The multi-site-modification of NHC-boranes is proved to be more effective for reduction of the B-H bond dissociation energy (BDE), promotion of the HAA reaction, and the reactivity regulation of their corresponding NHC-boryl radicals. Computational screening reveals that the spin density and the charge population of the radical boron center have good correlation with the B-H BDEs of NHC-boranes and the chemical reactivities of NHC-boryl radicals, and they can be considered as property and reactivity descriptors of these boron-based systems. The present results and established scaling relationships are beneficial to promote the advancement of design of NHC-boryl radical catalysis.
Collapse
Affiliation(s)
- Lin Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, China.
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, China.
| |
Collapse
|
2
|
Wu C, Hou X, Zheng Y, Li P, Lu D. Electrophilicity and Nucleophilicity of Boryl Radicals. J Org Chem 2017; 82:2898-2905. [PMID: 28224797 DOI: 10.1021/acs.joc.6b02849] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We carried out a survey of the relative reactivity of a collection of 91 neutral boryl radicals using density functional calculations. Their reactivities were characterized by four indices, i.e., the global electrophilicity, global nucleophilicity, local electrophilicity, and local nucleophilicity. Particularly, the global electrophilicity and nucleophilicity indices span over a moderately wider range than those of carbon radicals, indicating their potentially broader reactivity. Thus, boryl radicals may be utilized in electrophilic radical reactions, while traditionally they are only considered for nucleophilic radical reactions. In contrast, the local electrophilicity and nucleophilicity indices at the boron center show a different reactivity picture than their global counterparts. The inconsistency is rooted in the low and varying spin density on boron (for most radicals, less than 50%) in different boryl radicals, which is a combinative result of radical stabilization via electron delocalization and the low electronegativity of boron (compared to carbon). In short, the boron character in boryl radicals may be weak and their reactivity is not reflected by the local indices based on boron but by the global ones.
Collapse
Affiliation(s)
- Chao Wu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Xiufang Hou
- College of Chemistry and Chemical Engineering, Yan'an University , Yan'an 716000, China
| | - Yuheng Zheng
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Pengfei Li
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Dongmei Lu
- Department of Applied Chemistry, School of Science, Xi'an Jiaotong University , Xi'an 710049, China
| |
Collapse
|
8
|
Curran DP, Solovyev A, Makhlouf Brahmi M, Fensterbank L, Malacria M, Lacôte E. Synthesis and reactions of N-heterocyclic carbene boranes. Angew Chem Int Ed Engl 2011; 50:10294-317. [PMID: 21898724 DOI: 10.1002/anie.201102717] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Indexed: 11/10/2022]
Abstract
Boranes are widely used Lewis acids and N-heterocyclic carbenes (NHCs) are popular Lewis bases, so it is remarkable how little was known about their derived complexes until recently. NHC-boranes are typically readily accessible and many are so stable that they can be treated like organic compounds rather than complexes. They do not exhibit "borane chemistry", but instead are proving to have a rich chemistry of their own as reactants, as reagents, as initiators, and as catalysts. They have significant potential for use in organic synthesis and in polymer chemistry. They can be used to easily make unusual complexes with a broad spectrum of functional groups not usually seen in organoboron chemistry. Many of their reactions occur through new classes of reactive intermediates including borenium cations, boryl radicals, and even boryl anions. This Review provides comprehensive coverage of the synthesis, characterization, and reactions of NHC-boranes.
Collapse
Affiliation(s)
- Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | | | | | | | | | | |
Collapse
|
10
|
Nozaki K, Aramaki Y, Yamashita M, Ueng SH, Malacria M, Lacôte E, Curran DP. Boryltrihydroborate: Synthesis, Structure, and Reactivity as a Reductant in Ionic, Organometallic, and Radical Reactions. J Am Chem Soc 2010; 132:11449-51. [DOI: 10.1021/ja105277u] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kyoko Nozaki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Yoshitaka Aramaki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Makoto Yamashita
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Shau-Hua Ueng
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Max Malacria
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Emmanuel Lacôte
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| | - Dennis P. Curran
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, and UPMC Univ Paris 06, Institut Parisien De Chimie Moléculaire (UMR CNRS 7201), C 229, 4 place Jussieu, 75005 Paris, France
| |
Collapse
|