Wydział Chemii

Yuzhuo Sha

Wenchao Chu

Roger Lalancette

Roman Szostak

Michal Szostak

2025

Organometallics

44

1848-1853

10.1021/acs.organomet.5c00232

Naukowa

Angielski

Artykuł

There is a strong demand for the development of sterically hindered N-heterocyclic carbenes due to their potential to stabilize reactive organometallic species. IPr* (IPr* = 1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazo-2-ylidene) is a highly hindered and sterically flexible ligand, which has found broad utilization in coordination chemistry. Herein, we report the synthesis, structural, and electronic characterization of IPr**^(4-Bp)─a class of novel, sterically bulky, and easily accessible N-heterocyclic carbene ligands that bear biphenyl wingtips. Coordination chemistry to Ag(I), Cu(I), and Pd(II) is presented. The biphenyl wingtip permits extension of the %V_bur of IPr**^(4-Bp) to 58.8%, linear geometry, which is the highest reported to date for imidazol-2-ylidene ligands. The synthesis of an electron-rich congener, IPr**^MeO(4-Bp), which is analogous to the popular IPr*^MeO ligand, is also presented. Coordination to Pd(II) demonstrates steric flexibility, where the %V_bur changes to 42.8% for square planar geometry. The study demonstrates that IPr^**(4-Bp) with an extended biphenyl wingtip is sterically bulkier than common imidazol-2-ylidenes, including IPr, IPr*, IPr^#, and IPr*^(2-Np). Considering the essential role of sterically hindered N-heterocyclic carbene ligands in various areas of coordination chemistry and metal catalysis, this new class of NHCs is poised for rapid and widespread application.

Aromatic compounds, Carbene compounds, Hydrocarbons, Ligands, Metals

CC-BY

http://dx.doi.org/10.1021/acs.organomet.5c00232

https://www.acs.org/content/acs/en.html