Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

Abstract

Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

Expanding the Variety of Zirconium‐based Inorganic Building Units for Metal–Organic Frameworks

“…Theq uality of the extracted reflection intensities can be increased by coupling ADT with precession electron diffraction (PED). [36][37][38][39][40] Arylboronic acids are very important intermediates in organic synthesis that can be used in ap lethora of synthetic procedures. [34,35] This is especially relevant in the rich domain of C À Ha ctivation catalysis,w ith formation of for example,C ÀC, CÀN, or CÀBb onds.…”

Homogeneity of Surface Sites in Supported Single-Site Metal Catalysts: Assessment with Band Widths of Metal Carbonyl Infrared Spectra

“…10-12 ,. 4,5,6 Further, the ν CO values IR spectra similarly provideinge essential details of the local environments of metal sites on solid surfaces. 713 The typical mononuclear metal carbonyl complex on a metal oxide support is heterogeneous, characterized by a smear of species and broad ν CO bands, but Miessner et al 8 14 showed that mononuclear rhodium carbonyls bonded to dealuminated HY zeolite are characterized by narrow ν CO bands, indicating that the zeolite bonding sites are almost all the same.…”

Recent Advances of MOFs and MOF‐Derived Materials in Thermally Driven Organic Transformations

“…As an example, in 2016, Lin and co‐workers reported the post‐synthetic metalation of Zr 6 (μ 3 ‐O) 4 (μ 3 ‐OH) 4 ‐nodes in UiO‐68 by soaking the material in solutions of Co 2+ and Fe 2+ salts. It was suggested, according to X‐ray absorption spectroscopy, that the added metals bind to the (μ 3 ‐OH) bridge found on the surface of the SBU (Figure ) . The introduction of site isolated, coordinatively deficient Lewis acids in the MOF pore, transformed the MOF into a highly active, reusable catalysts, which has demonstrated utility in a variety of site‐selective sp 3 C‐H functionalization, including benzylic C−H borylation, silylation and amination reactions.…”

“… (A) Metalation of the SBUs of UiO‐68 with CoCl 2 . (B) An electron‐deficient Co II center located in a sterically protected environment at the SBU of UiO‐68 will favor the activation of less‐hindered alkyl C−H bonds . Copyright 2016 Springer Nature.…”