Affiliation:
1. Department of Chemistry Temple University Beury Hall 1901N 13th St Philadelphia PA 19122 USA
2. Department of Chemistry Hylleraas Centre for Quantum Molecular Sciences and Centre for Materials Science and Nanotechnology University of Oslo Blindern, P.O. Box 1033, 0315 Oslo Norway
Abstract
AbstractThe catalytic one‐bond isomerization (transposition) of 1‐alkenes is an emerging approach to Z‐2‐alkenes. Design of more selective catalysts would benefit from a mechanistic understanding of factors controlling Z selectivity. We propose here a reaction pathway for cis‐Mo(CO)4(PCy3)(piperidine) (3), a precatalyst that shows high Z selectivity for transposition of alpha olefins (e. g., 1‐octene to 2‐octene, 18 : 1 Z : E at 74 % conversion). Computational modeling of reaction pathways and isotopic labeling suggests the isomerization takes place via an allyl (1,3‐hydride shift) pathway, where oxidative addition of fac‐(CO)3Mo(PCy3)(η2‐alkene) is followed by hydride migration from one position (cis to allyl C3 carbon) to another (cis to allyl C1 carbon) via hydride/CO exchanges. Calculated barriers for the hydride migration pathway are lower than explored alternative mechanisms (e. g., change of allyl hapticity, allyl rotation). To our knowledge, this is the first study to propose such a hydride migration in alkene isomerization.
Funder
National Science Foundation
Pennsylvania Department of Health
Norges Forskningsråd
Army Research Laboratory
Subject
Inorganic Chemistry,Organic Chemistry,Physical and Theoretical Chemistry,Catalysis