An ionic Fe-based metal–organic-framework with 4′-pyridyl-2,2′:6′,2′′-terpyridine for catalytic hydroboration of alkynes

Abstract

An ionic metal–organic-framework (MOF) containing nanoscale channels was readily assembled from ditopic 4′-pyridyl-2,2′:6′,2′′-terpyridine (pytpy) and a simple iron(II) salt. X-ray structural analysis revealed a two-dimensional grid-like framework assembled by classic octahedral (pytpy)₂Fe^II cations as linkers (with pytpy as a new ditopic pyridyl ligand) and octa-coordinate FeCl₂ centers as nodes. The layer-by-layer assembly of the 2-D framework resulted in the formation of 3-D porous materials consisting of nano-scale channels. The charges of the cationic framework were balanced with anionic Cl₃FeOFeCl₃ in its void channels. The new Fe-based MOF material was employed as a precatalyst for syn-selective hydroboration of alkynes under mild, solvent-free conditions in the presence of an activator, leading to the synthesis of a range of trans-alkenylboronates in good yields. The larger scale applicability and recyclability of the new MOF catalyst was further explored. This represents a rare example of an ionic MOF material that can be utilized in hydroboration catalysis.