Work

Reversible N‐Heterocyclic Carbene‐Induced α‐H Abstraction in Tungsten(VI) Imido Dialkyl Dialkoxide Complexes

Year: 2020

Type: article

Abstract: The first reversible N‐heterocyclic carbene (NHC) induced α‐H abstraction in tungsten(VI) imido‐dialkyl dialkoxide complexes is reported. Treatment of W(NAr)(CH2Ph)2(OtBu)2 (Ar=2,6‐dichlorophenyl, 2,6‐dimethylphenyl, 2,6‐diisopropylphenyl) with different NHCs leads to the formation of complexes of the type W(NAr)(CHPh)(NHC)(CH2Ph)(OtBu) in excellent isolated yields of up to 96 %. The highly unusual release of the tert‐butoxide ligand as tBuOH in the course of the reaction was observed. The formed alkylidene complexes and tBuOH are in an equilibrium with the NHC and the dialkyl complexes. Reaction kinetics were monitored by 1H NMR spectroscopy. A correlation between the steric and electronic properties of the NHC and the reaction rates was observed. Kinetics of a deuterium‐labeled complex in comparison to its non‐deuterated counterpart revealed the presence of a strong primary kinetic isotope effect (KIE) of 4.2, indicating that α‐H abstraction is the rate‐determining step (RDS) of the reaction.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202000840

Authors: Janis V. Musso, Mathis J. Benedikter, Dongren Wang, Wolfgang Frey, Hagen J. Altmann, Michael R. Buchmeiser

Institutions: University of Stuttgart, Deutschen Institute für Textil und Faserforschung

Language: English

Topic: N-Heterocyclic Carbenes in Organic and Inorganic Chemistry

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,000

Funder: Deutsche Forschungsgemeinschaft