N₂ Dissociation vs Reversible 1,2-Methyl Migration in PC_NHCP Cobalt(I) Complexes in the Stereoselective Isomerization (E/Z) of Allyl Ethers

Abstract

With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PC NHC P pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PC NHC P)Co) 2 -μ-N 2 ][BAr 4 F ] 2 (3) mainly favors the Z-isomer of the enol ether, the corresponding methyl complex [(PC NHC P)CoMe] (4) mostly gives the E-isomer. The dichotomy in selectivity was investigated computationally, revealing important contributions from the substituents on the metal (N 2 vs Me), including a 1,2-alkyl migration from cobalt to the N-heterocyclic carbene (NHC) of the methyl substituent, which is further explored in this report.