Synthesis and Characterization of Pincer-Molybdenum Precatalysts for CO2 Hydrogenation

Synthesis and Characterization of Pincer-Molybdenum Precatalysts for CO2 Hydrogenation

Yuanyuan Zhang†‡, Paul G. Williard‡, and Wesley H. Bernskoetter*†‡
† Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
‡ Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
Organometallics, Article ASAP
DOI: 10.1021/acs.organomet.5b00955
Publication Date (Web): January 19, 2016








A family of low-valent molybdenum complexes supported by the pincer ligand PNMeP (PNMeP = MeN(CH2CH2PPh2)2) was prepared and characterized, including (PNMeP)Mo(C2H4)2, which contains an agostic interaction between the metal and the N-methyl substituent. This β-agostic C–H bond was cleaved by molybdenum and produced a cyclometalated molybdenum formate complex, (κ4-PNMeP)Mo(C2H4)(κ2-O2CH), upon exposure to CO2. This species serves as a promotor of CO2 hydrogenation to formate under basic conditions, a rare transformation for group VI metals. The performance of the precatalyst was enhanced with the addition of Lewis acid salts.

A Highly Efficient Heterogenized Iridium Complex for the Catalytic Hydrogenation of Carbon Dioxide to Formate

A Highly Efficient Heterogenized Iridium Complex for the Catalytic Hydrogenation of Carbon Dioxide to Formate (pages 3410–3413)
Kwangho Park, Gunniya Hariyanandam Gunasekar , Natarajan Prakash, Dr. Kwang-Deog Jung and Prof. Dr. Sungho Yoon
Article first published online: 25 AUG 2015 | DOI: 10.1002/cssc.201500436

Complex in New Basket: A new, highly porous, industrially viable, heterogenized Ir catalyst has been synthesized and characterized, and the coordination environment is confirmed to be similar to that of its homogeneous counterpart. The catalyst efficiently converts CO₂ to formate through hydrogenation at high turnover frequencies (TOFs) and turnover numbers (TONs) and shows good stability during the recycling process.

Abstract

A heterogenized catalyst on a highly porous covalent triazine framework was synthesized and characterized to have a coordination environment similar to that of its homogeneous counterpart. The catalyst efficiently converted CO₂ into formate through hydrogenation with a turnover number of 5000 after 2 h and an initial turnover frequency of up to 5300 h⁻¹; both of these values are the highest reported to date for a heterogeneous catalyst, which makes it attractive toward industrial application. Furthermore, the synthesized catalyst was found to be stable in air and was recycled by simple filtration without significant loss of catalytic activity.
 

http://onlinelibrary.wiley.com/doi/10.1002/cssc.201500436/full