Work

Olefin Metathesis Catalyst Supported by a Hemilabile NHC Ligand Bearing Polyether Arms: Structure, Activity, and Decomposition

Year: 2020

Type: article

Abstract: An olefin metathesis catalyst ( 8 ) bearing a hemilabile N-heterocyclic carbene (NHC) ligand with four methoxyethoxy arms was synthesized and analyzed by X-ray crystallography and NMR spectroscopy. The solid-state structure of the catalyst reveals that one of the aromatic rings is rotated toward the plane of the NHC heterocycle, which enables one ortho-O→Ru coordination. Ring-closing metathesis (RCM) activity was tested at low catalyst loadings. Catalyst 8 was found to display a significant rate enhancement relative to the commercial catalyst 3 but offered no improvement in turnover numbers (TON). The solid-state structure of the catalyst’s major degradation product ( 9 ) in the presence of 1-hexene reveals a dinuclear compound containing a bridging methylidene (Ru–CH 2 –Ru), indicating that the methoxyethoxy arms may not be strong enough to stabilize the (NHC)RuCl 2 (═CH 2 ) catalyst resting state.

Source: Organometallics

DOI: 10.1021/acs.organomet.9b00832

Authors: Jordan D. Carter, Yann Schrodi

Institution: California State University, Northridge

Language: English

Topic: Synthetic Organic Chemistry Methods

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funder: National Institute of General Medical Sciences

Award: New Robust Olefin Metathesis Catalysts Based on Non-Toxic and Abundant Low-Valent Molybdenum