Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal–Organic Framework

Abstract

A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX](4-) = [(2,6-(OPAr2)2C6H3)PdX](4-), Ar = p-C6H4CO2(-), X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I(-)/CF3CO2(-) ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue (t)Bu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.

Incorporation of PdCl2P2 Complexes in Ni‐MOF for Catalyzing Heck Arylation of Functionalized Olefins

“…Phosphine ligands play an important role in the creation of highly active metal catalysts, creating an optimal environment for substrates activation through electronic and steric influence . In palladium catalytic systems, phosphines stabilize metal complexes and promote a homogeneous reaction pathway.…”

Halide exchange studies of novel Pd(ii) NNN-pincer complexes

“…Pincer metal complexes in which three donor sites of the ligand stabilize a planar metal center have been studied extensively. Variations to the so-called ECE type ligand (Chart 1) where E symbolizes coordination through anking NR 2 , PR 2 , SR, SeR or OR groups afford complexes with applications especially in catalysis [1][2][3][4][5][6][7][8] but also in other elds including sensing, 6,9-12 materials science [13][14][15][16][17][18][19] and medicinal chemistry. 18,20 Among various metals, palladium is one of the most studied owing mainly to its importance in organic synthesis.…”

A Bifunctional MOF Catalyst Containing Metal–Phosphine and Lewis Acidic Active Sites

“…These mayb et ransitionmetal atoms bound at sites pre-designed by linker choice, intact transition-metalp re-catalysts, precious metal nanoparticles or even enzymes. [4][5][6] In these cases, ac atalystk nown to be active under homogeneous conditions is immobilised in a well-defined, highlyp orous and tunable( but otherwise inert) crystalline environment. Attractive opportunities arise for the wider application of MOF catalysis whereby synergistic use can be made of active sites at framework metal cations anda dditional catalytic species incorporated by design into the MOF.A few initial papersh ave appearedt hat point towards ab right future for this approach.…”

“…Typically,m any different phosphorous ligands are tested, leading to the identification of ap romising catalyst that is then further optimised fora pplication.R elativelyf ew synthetic routes to phosphine-functionalised MOFs have been developed so far.P ioneering works on MOF-containing phosphorousc ompounds report preparation of novel phosphinefunctionalised linkersa nd their incorporation into MOFs via coordination with as uitable metal. [5,8] However, this route is inconsistentw ith the practicallyi mportant requirementt oe xamine various ligand parameters by testing libraries of new ligands. Neitherd oes it lend itself to the reliable preparation of as eries of MOFs with coordinativelyu nsaturated metal cation sites and similarp ore sizes, forw hich the effecto fv arying a single parameter-the metal-phosphine actives ite-can be monitored.…”