Synthesis, Structural Analysis, and Catalysis for Suzuki–Miyaura Coupling Reactions of Tetradentate N ^ C ^ C ^ N and Tetracarbene C ^ C ^ C ^ C Nickel– N ‐Heterocyclic Carbene Complexes
Year: 2025
Type: article
Abstract: ABSTRACT Four novel Ni(II)– N ‐heterocyclic carbene (Ni–NHC) complexes were synthesized and characterized by NMR, ESI–MS, SEM, TEM, EDS mapping, XPS, and single‐crystal X‐ray diffraction (XRD) analysis. Ni–NHC complexes 7 and 8 are intramolecular tetradentate N ^ C NHC ^ C NHC ^ N‐cyclometalated [1L + 1M] complex featuring coplanar of azole and quinoline rings, and Ni–NHC complex 11 is an interligand tetracarbene C NHC ^ C NHC ^ C NHC ^ C NHC ‐cyclometalated [2L + 1M] complex with two six‐membered, conformation of boat‐shaped, C NHC ^ C NHC ‐cyclometalated structural units. Complex 9@Ni–NHC is a softly fluffy black powder with the surface morphology of a tightly arranged honeycomb‐like pore structure and may be an interligand tetracarbene C NHC ^ C NHC ^ C NHC ^ C NHC ‐cyclometalated [2L + 1M] structure containing a very small amount of Ni 0 state. DFT calculations suggested enhanced stability for tetracarbene C NHC ^ C NHC ^ C NHC ^ C NHC ‐cyclometalated complexes 9@Ni–NHC and 11 . Cyclic voltammetry studies shown that complexes 7 , 8 , and 9@Ni–NHC have similar redox properties of two pairs of redox peaks, and complex 11 displays only one reversible redox process with half‐wave potentials at E 1/2 = −0.864 V. All complexes were found to be efficient catalysts for the Suzuki–Miyaura cross‐coupling reaction, and complexes 7 and 8 display better catalytic activity than complexes 9@Ni–NHC and 11 and exhibit catalytic activity comparable to Pd(OAc) 2 catalyst, which may be attributed to the intraligand chelating tetradentate coordination and the coplanar conjugate effect between the azole and quinoline rings.
Source: Applied Organometallic Chemistry
DOI: 10.1002/aoc.7971
Authors: Chen Gao, Wen‐Qi Luo, Xiao Xiao, Hai‐Juan Shuai, Ling‐Ying Chen, Chuan‐Ming Jin
Institution: Hubei Normal University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: bronze
Award: G7334259065
OpenAlex ID: W4406594635