Investigations on stability and reusability of [Pd(2-pymo)2]n as hydrogenation catalyst

Simultaneous introduction of various palladium active sites into MOF via one-pot synthesis: Pd@[Cu3−xPdx(BTC)2]n

“…30 To the best of our knowledge, studies on integration of palladium as a framework node into a MOF are thus far in its infancy. [30][31][32][33] Reports on MOFs featuring Pd-Pd and Pd-M paddlewheel nodes could not be found. Interestingly, bimetallic Pd/M-paddlewheel complexes have been lately found to be promising economical catalysts in the intramolecular benzylic C-H amination.…”

“…Both Pd 2+ -containing MOF ([Pd(2-pymo) 2 ] n , 2-pymo = 2-pyrimidinolate) [31][32][33] and Pd 0 @MOF, 38,42,43,45 have been reported as good reusable catalysts in typical palladium-catalyzed reactions such as Suzuki C-C couplings and hydrogenation. Owing to both Pd 0 NPs and potential Pd 2+ -CUS (that should be available after thermal treatment and specifically promote H 2 splitting) in obtained Pd-containing Cu/Pd-BTC materials, it was of interest to test their catalytic activity in hydrogenation reactions.…”

“…Moreover, it has been reported that Pd 2+ can act as active metal sites in olefin hydrogenations. [31][32][33] It can be noted that PXRD patterns of the Cu/Pd-BTC samples before and after reaction indicate that the structure of the framework remains unchanged (Fig. S17 †).…”

The Role of Pd2+/Pd0 in Hydrogenation by [Pd(2‐pymo)2]n: An X‐ray Absorption and IR Spectroscopic Study

“…The hydrogenation activity of the metal organic framework (MOF) [PdA C H T U N G T R E N N U N G (2-pymo) 2 ] n (2-pymo = 2-pyrimidinolate) in the liquid-phase conversion of 1-octene with molecular hydrogen was reported by Xamena et al [1] The MOF [PdA C H T U N G T R E N N U N G (2pymo) 2 ] n consists of Pd 2 + ions bridged by N,N'-exobidentate 2-pymo linkers to build up a three-dimensional open sodalite-like framework. [2] Recently, we reported on the stability and reusability of this MOF in liquid-phase hydrogenation reactions [3] and showed that [PdA C H T U N G T R E N N U N G (2-pymo) 2 ] n does not have long-term stability in liquid-phase catalytic hydrogenation because of reduction of the Pd 2 + centers to Pd 0 . Visually, a color change of the catalyst was observed, and ex situ XRD showed the formation of Pd 0 nanoparticles.…”

“…These Pd 0 nanoparticles were detectable by XRD in catalyst samples which had been in contact with hydrogen for at least 5 h. In addition, elemental analysis and solid-state 1 H NMR spectrosco-py showed that the linker molecules of these catalyst samples were hydrogenated and protonated. [3] To gain more detailed, especially time-resolved, insights into the reaction mechanism, in situ measurements by X-ray absorption spectroscopy (XAS) and IR spectroscopy are presented herein to clarify whether hydrogenation reaction takes place at the Pd 2 + nodes of the intact MOF structure or at reduced Pd 0 sites of the collapsed MOF. While IR spectroscopy yields mainly information about the organic scaffold through vibrations of the organic groups, XAS is an element-specific tool providing the local structure and oxidation state at the metal center.…”