In-situ Generation of An N-Heterocyclic Carbene-Functionalized Metal-Organic Framework via Postsynthetic Ligand Exchange for Efficient and Selective Hydrosilylation of CO2.

We report a metal-organic framework (MOF) catalyst that realizes the CO2 to methanol transformation under ambient conditions. The MOF is one rare example containing metal-free N-heterocyclic carbene (NHC) moieties, which are installed using an in-situ generation strategy involving the incorporation of an imidazolium bromide-based linker into the MOF by postsynthetic ligand exchange. Importantly, the resultant NHC-functionalized MOF is the first catalyst capable of perform quantitative hydrogen-transfer from silanes to CO2, thus achieving quantitative (>99%) methanol yield. Density functional theory calculations indicate the high catalytic activity of the NHC sites in MOFs are attributed to the decreased reaction barrier of a reaction route involving the formation of an NHC-silane adduct. In addition, the MOF-immobilized NHC catalyst shows enhanced stability for up to eight cycles without base activation as well as high selectivity towards the desired silyl methoxide product.
PMID: 30609209 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - January 4, 2019 Category: Chemistry Authors: Zhang X, Sun J, Wei G, Liu Z, Yang H, Wang K, Fei H Tags: Angew Chem Int Ed Engl Source Type: research