Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes

Liang, Mei-Juan; Chen, Ke-Cheng; Cui, Zhongzheng; Zhou, Yan-Chang; Wang, Yan; Qi, Fan; Xiao, Xu-Qiong

doi:10.3390/inorganics13060179

This is an early access version, the complete PDF, HTML, and XML versions will be available soon.

Open AccessArticle

Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes

by

Mei-Juan Liang

^†

,

Ke-Cheng Chen

^†,

Zhongzheng Cui

,

Yan-Chang Zhou

,

Yan Wang

,

Fan Qi

^* and

Xu-Qiong Xiao

^*

Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Key Laboratory of Silicone Materials Technology of Zhejiang Province, College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, No. 2318 Yuhangtang Rd., Hangzhou 311121, China

^*

Authors to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Inorganics 2025, 13(6), 179; https://doi.org/10.3390/inorganics13060179

Submission received: 2 April 2025 / Revised: 17 May 2025 / Accepted: 24 May 2025 / Published: 25 May 2025

(This article belongs to the Topic Heterocyclic Carbene Catalysis)

Download

Browse Figure

Versions Notes

Abstract

N-Heterocyclic carbenes (NHCs) have been widely utilized over the past three decades due to their broad applications, yet synthetic methods for their preparation remain limited. A promising approach for NHC generation involves the thermolysis of NHC adducts. Herein, we report the synthesis of NHC pentafluorobenzene adducts featuring an o-carboranyl group in the backbone (2), which, unlike previously studied systems, resists thermal decomposition. Density functional theory (DFT) calculations were used to investigate the discrepancy, revealing that the decomposition reaction is kinetically controlled. For widely studied NHC systems like IMes and SIMes, the activation barriers were calculated to be 246.3 kJ/mol and 267.3 kJ/mol, respectively, aligning with reactions requiring heating. In contrast, the o-carborane system exhibited a significantly higher barrier of 320.5 kJ/mol, primarily due to the structural influence of the o-carborane backbone. Further analysis indicates that delocalization of π-electrons from the backbone into the NHC’s p-orbitals lowers the activation barrier, whereas delocalization into an exo-NHC ring increases it. These findings provide new insights into the thermal generation of NHCs and we hope it can offer guidance for future NHC design and synthesis.

Keywords: carborane; N-heterocyclic carbene; thermal generation; DFT calculation

Graphical Abstract

Share and Cite

MDPI and ACS Style

Liang, M.-J.; Chen, K.-C.; Cui, Z.; Zhou, Y.-C.; Wang, Y.; Qi, F.; Xiao, X.-Q. Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes. Inorganics 2025, 13, 179. https://doi.org/10.3390/inorganics13060179

AMA Style

Liang M-J, Chen K-C, Cui Z, Zhou Y-C, Wang Y, Qi F, Xiao X-Q. Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes. Inorganics. 2025; 13(6):179. https://doi.org/10.3390/inorganics13060179

Chicago/Turabian Style

Liang, Mei-Juan, Ke-Cheng Chen, Zhongzheng Cui, Yan-Chang Zhou, Yan Wang, Fan Qi, and Xu-Qiong Xiao. 2025. "Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes" Inorganics 13, no. 6: 179. https://doi.org/10.3390/inorganics13060179

APA Style

Liang, M.-J., Chen, K.-C., Cui, Z., Zhou, Y.-C., Wang, Y., Qi, F., & Xiao, X.-Q. (2025). Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes. Inorganics, 13(6), 179. https://doi.org/10.3390/inorganics13060179

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Menu

Experimental Attempts at and Theoretical Study of the Thermal Generation of o-Carborane-Supported N-Heterocyclic Carbenes

Abstract

Share and Cite

Article Metrics

Article Access Statistics

Further Information

Guidelines

MDPI Initiatives

Follow MDPI