Base- and Additive-Free Carbon Dioxide Hydroboration to Methoxyboranes Catalyzed by Non-Pincer-Type Mn(I) Complexes

Sylwia Kostera; Stefan Weber; Ines Blaha; Maurizio Peruzzini; Karl Kirchner; Luca Gonsalvi

doi:10.1021/acscatal.3c00020

Base- and Additive-Free Carbon Dioxide Hydroboration to Methoxyboranes Catalyzed by Non-Pincer-Type Mn(I) Complexes

ACS Catal. 2023 Mar 31;13(8):5236-5244. doi: 10.1021/acscatal.3c00020. eCollection 2023 Apr 21.

Authors

Sylwia Kostera¹, Stefan Weber², Ines Blaha², Maurizio Peruzzini¹, Karl Kirchner², Luca Gonsalvi¹

Affiliations

¹ Consiglio Nazionale delle Ricerche (CNR), Istituto di Chimica dei Composti Organometallici (ICCOM), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze, Italy.
² Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-AC, A-1060 Wien, Austria.

Abstract

Well-defined, bench stable Mn(I) non-pincer-type complexes were tested as earth-abundant transition metal catalysts for the selective reduction of CO₂ to boryl-protected MeOH in the presence of pinacolborane (HBpin). Essentially, quantitative yields were obtained under mild reaction conditions (1 bar CO₂, 60 °C), without the need of any base or additives, in the presence of the alkylcarbonyl Mn(I) bis(phosphine) complexes fac-[Mn(CH₂CH₂CH₃)(dippe)(CO)₃] [Mn1, dippe = 1,2-bis(diisopropylphosphino)ethane] and [Mn(dippe)(CO)₂{(μ-H)₂(Bpin)}] (Mn4), that is obtained by reaction of the bench-stable precatalyst Mn1 with HBpin via elimination of butanal. Preliminary mechanistic details were obtained by a combination of NMR experiments and monitoring of the catalytic reactions.