590-29-4Relevant articles and documents
Catalytic hydrogenation of carbon dioxide using Ir(III)-pincer complexes
Tanaka, Ryo,Yamashita, Makoto,Nozaki, Kyoko
, p. 14168 - 14169 (2009)
(Chemical Equation Presented) Catalytic hydrogenation of carbon dioxide in aqueous potassium hydroxide was performed using a newly synthesized isopropyl-substituted PNP-pincer iridium trihydride complex as a catalyst. Potassium formate was obtained with t
Arene ruthenium oxinato complexes: Synthesis, molecular structure and catalytic activity for the hydrogenation of carbon dioxide in aqueous solution
Thai, Trieu-Tien,Therrien, Bruno,Süss-Fink, Georg
, p. 3973 - 3981 (2009)
Two families of arene ruthenium oxinato complexes of the types [(η6-arene)Ru(η2-N,O-L)Cl] and [(η6-arene)Ru(η2-N,O-L)(OH2)]+ have been synthesized from the dinuclear precursors [(η6/s
Synthetic routes to a coordinatively unsaturated ruthenium complex supported by a tripodal, protic bis(N-heterocyclic carbene) phosphine ligand
Flowers,Johnson,Pitre,Cossairt
, p. 1276 - 1283 (2018)
A facile, one pot synthesis of a coordinatively unsaturated ruthenium complex supported by a tripodal, protic bis(N-heterocyclic carbene) phosphine ligand is presented. A number of coordination complexes were discovered en route during this synthesis, revealing some of the unique aspects of complexes ligated by this type of tridentate, protic bis(NHC) ligand. Through a combination of 1D and 2D NMR spectroscopic analysis and single crystal X-ray diffraction, we reveal the intermediacy of phosphine-ligated bisimidazole complexes and show that abstraction of inner-sphere halide ions facilitates conversion to the desired tridentate bis(NHC) coordination mode. Ultimately the use of N-methyl-2-pyrrolidone is shown to enable the use of the extreme temperatures needed to facilitate the direct, thermally activated tautomerization reaction that gives rise to the bis(NHC) motif.
Enhanced CO2 electroreduction efficiency through secondary coordination effects on a pincer iridium catalyst
Ahn, Steven T.,Bielinski, Elizabeth A.,Lane, Elizabeth M.,Chen, Yanqiao,Bernskoetter, Wesley H.,Hazari, Nilay,Palmore, G. Tayhas R.
, p. 5947 - 5950 (2015)
An iridium(iii) trihydride complex supported by a pincer ligand with a hydrogen bond donor in the secondary coordination sphere promotes the electrocatalytic reduction of CO2 to formate in water/acetonitrile with excellent Faradaic efficiency and low overpotential. Preliminary mechanistic experiments indicate formate formation is facile while product release is a kinetically difficult step.
Transfer hydrogenation of carbon dioxide: Via bicarbonate promoted by bifunctional C-N chelating Cp?Ir complexes
Sato, Yasuhiro,Kayaki, Yoshihito,Ikariya, Takao
, p. 10762 - 10765 (2020)
Metal-ligand cooperative Cp?Ir(iii) complexes derived from primary benzylic amines effectively promote transfer hydrogenation of atmospheric CO2 using 2-propanol at 80 °C. Isotope-labelling experiments strengthen that active Ir species can preferentially reduce bicarbonate congeners formed from CO2. The powerful transfer hydrogenation catalyst exhibits remarkable activity for the conversion of bicarbonates into formate salts with a turnover number up to 3200, even without H2 and CO2.
CO2Hydrogenation Catalyzed by a Ruthenium Protic N-Heterocyclic Carbene Complex
Johnson, M. Cecilia,Rogers, Dylan,Kaminsky, Werner,Cossairt, Brandi M.
, p. 5996 - 6003 (2021)
We describe the hydrogenation of CO2 to formate catalyzed by a Ru(II) bis(protic N-heterocyclic carbene, p-NHC) phosphine complex [Ru(bpy)(MeCN)(PPh(p-NHC)2)](PF6)2 (1). Under catalytic conditions (20 μmol catalyst, 20 bar CO2, 60 bar H2, 5 mL THF, 140 °C, 16 h), the activity of 1 is limited only by the amount of K3PO4 present in the reaction, yielding a nearly 1:1 ratio of turnover number (TON) to equivalents of K3PO4 (relative to 1), with the highest TON = 8040. Additionally, analysis of the reaction solution post-run reveals the catalyst intact with no free ligand observed. Stoichiometric studies, including examination of unique carbamate and hydride complexes as relevant intermediates, were carried out to probe the operative mechanism and understand the importance of metal-ligand cooperativity in this system.
Interconversion between formic acid and H2/CO2 using rhodium and ruthenium catalysts for CO2 fixation and H2 storage
Himeda, Yuichiro,Miyazawa, Satoru,Hirose, Takuji
, p. 487 - 493 (2011)
The interconversion between formic acid and H2/CO2 using half-sandwich rhodium and ruthenium catalysts with 4,4'-dihydroxy-2,2'- bipyridine (DHBP) was investigated. The influence of substituents of the bipyridine ligand was studied. Chemical shifts of protons in bipyridine linearly correlated with Hammett substituent constants. In the hydrogenation of CO 2/bicarbonate to formate under basic conditions, significant activations of the catalysts were caused by the electronic effect of oxyanions generated by deprotonation of the hydroxyl group. Initial turnover frequencies of the ruthenium- and rhodium-DHBP complexes increased 65- and 8-fold, respectively, compared to the corresponding unsubstituted bipyridine complexes. In the decomposition of formic acid under acidic conditions, activity enhancement by the electronic effect of the hydroxyl group was observed for the ruthenium catalyst. The rhodium-DHBP catalyst showed high activity without CO contamination in a relatively wide pH range. Pressurized H2 can be obtained using an autoclave reactor. The highest turnover frequency and number were obtained at 80°C. The catalytic system provides valuable insight into the use of CO2 as a H2 storage material by combining CO2 hydrogenation with formic acid decomposition.
Role of ligand-bound CO2in the hydrogenation of CO2to formate with a (PNP)Mn catalyst
Christensen, Elizabeth G.,Lutz, Kevin T.,McDonald, Gabriel R.,Saouma, Caroline T.,Schlenker, Kevin,Steele, Ryan P.,VanderLinden, Ryan T.,Yang, Emily L.,Zhanserkeev, Asylbek A.
, p. 8358 - 8369 (2021)
Herein, we describe the catalytic hydrogenation of CO2 to formate with (PNP)Mn-H (PNP = 2,6-bis(di-tert-butylphosphinomethyl)- pyridine; Mn = Mn(CO)2). Contrary to the established mechanism for CO2 hydrogenation, mechanistic studies indicate that CO2 does not insert into the Mn-H bond of (PNP)Mn-H to give the formate species, (PNP)Mn- OCHO. The lack of reactivity is confirmed by thermochemical studies that show that (PNP)Mn-H is not sufficiently hydridic to reduce CO2. Deprotonation of the hydride to give [(?PNP)Mn-H]- ((? indicates the deprotonated ligand) enhances the hydricity by ~17 kcal·mol-1 and hence should be sufficiently hydridic to hydrogenate CO2. This reactivity is not observed, and CO2 instead binds to the backbone to generate another anionic hydride species [(CO2-PNP)Mn-H]. The formate is lost only from this species, through hydride transfer to an external CO2. These findings are unexpected because substrate binding to the backbone of catalysts that can undergo metal-ligand cooperativity (MLC) is thought to be detrimental to catalysis; this work suggests that alternative mechanisms should be considered. The enhanced hydricity observed upon deprotonation may be broadly applicable to systems capable of undergoing MLC. Moreover, this work shows an example of how thermochemical analysis can be used to advance mechanistic understanding in (de)hydrogenation catalysis.
Hydrogenation of CO2 to Formate over Ruthenium Immobilized on Solid Molecular Phosphines
Kann, Anna,Hartmann, Heinrich,Besmehn, Astrid,Hausoul, Peter J. C.,Palkovits, Regina
, p. 1857 - 1865 (2018)
Formic acid is a promising hydrogen storage medium and can be produced by catalytic hydrogenation of CO2. Molecular ruthenium complexes immobilized on phosphine polymers have been found to exhibit excellent productivity and selectivity in the catalytic hydrogenation of CO2 under mild conditions. The polymeric analog of 1,2-bis(diphenylphosphino)ethane exhibited the highest activity and turnover numbers up to 13 170 were obtained in a single run. This catalyst was already active at 40 °C and with a catalyst loading of only 0.0006 mol %. Recycling experiments revealed a loss of activity after the first run, followed by a gradual decrease during the subsequent runs. This is attributed to a change in the catalytically active complex during the hydrogenation reaction. High selectivity towards formate and low leaching were maintained in the absence of CO formation. Based on the catalyst characterization, a mechanism for the CO2 hydrogenation is proposed.
CO2 activation by manganese pincer complexes through different modes of metal-ligand cooperation
Kumar, Amit,Daw, Prosenjit,Espinosa-Jalapa, Noel Angel,Leitus, Gregory,Shimon, Linda J. W.,Ben-David, Yehoshoa,Milstein, David
, p. 14580 - 14584 (2019)
We report here the activation of CO2 using two Mn-PNN pincer complexes that can exhibit different modes of metal-ligand cooperation amido/amino mode that involves [1,2]-activation of CO2 and dearomatization/aromatization mode that in
Communication—CO2 reduction to formate: An electro-enzymatic approach using a formate dehydrogenase from rhodobacter capsulatus
Choi, Eun-Gyu,Yeon, Young Joo,Min, Kyoungseon,Kim, Yong Hwan
, p. H446 - H448 (2018)
CO2 utilization for producing value-added chemicals has recently emerged as a strategy to mitigate atmospheric CO2 levels. Given that (i) certain formate dehydrogenases are capable of interconverting CO2 and formate, and (ii) formate is versatile in various industries, we, herein, aimed to demonstrate FDH-driven formate production from CO2. Because of its O2 stability, we selected FDH from Rhodobacter capsulatus (RcFDH) and then constructed a mediated electro-enzymatic system. The mediated electro-enzymatic kinetic parameters (kred and kox) were calculated to optimize the reaction conditions favorable for CO2 reduction. Finally, a RcFDH-driven electro-enzymatic system successfully produced 6 mM of formate in 5 hours.
Palladium(II) Immobilized on Metal-Organic Frameworks for Catalytic Conversion of Carbon Dioxide to Formate
Bingwa, Ndzondelelo,Makhubela, Banothile C. E.,Mehlana, Gift,Tshuma, Piwai
, p. 6717 - 6728 (2020)
In this work, we report the design of a two-dimensional (2D) isostructural metal-organic framework containing Pd(II) active sites, using a bipyridyl dicarboxylate linker (Mg(bpdc)(DMF)2PdCl2]n (Pd?Mg:JMS-2) and [Mn(bpdc)(DMF)2PdCl2]n(Pd?Mn:JMS-2)). The activated MOFs Pd?Mg:JMS-2a and Pd?Mn:JMS-2a were evaluated as heterogeneous catalysts for the hydrogenation of carbon dioxide (CO2) to formate. Under optimal conditions, the MOFs exhibited impressive catalytic activity with formate turnover numbers of 7272 and 9808 for Pd?Mg:JMS-2a and Pd?Mn:JMS-2a, respectively, after 24 h. These catalysts exhibited higher catalytic activity when compared to its homogeneous counterpart that was used as a linker during MOF synthesis. Post-experimental characterization showed that the structural integrity of the MOFs was not altered after catalysis. This work demonstrates that the catalytic activity of homogeneous systems can be enhanced under heterogeneous conditions by anchoring them on MOFs.
CO2 Conversion to formates catalyzed by iridium(III) catalysts precursors with proton responsive OH and NH electron-rich tetrazole ligands
Ocansey, Edward,Darkwa, James,Makhubela, Banothile C.E.
, (2021/12/03)
Recent efforts in addressing the environmental problems have involved using CO2 as a cheap and nontoxic C1 source. Iridium catalysts with bidentate ligands are excellent catalysts for CO2, especially if these complexes possess proton-responsive OH or NH groups. Here-in we report the synthesis of novel Ir half-sandwich complexes with N^N bidentate tetrazolyl ligands. Serendipitous deprotection of methoxy groups resulted in N^N bidentate ligands bearing OH groups. The complexes were evaluated for CO2 hydrogenation, for which the roles of steric bulk or the presence of electronic effects influence their catalytic activity in CO2 hydrogenation. The complexes are highly active for CO2 hydrogenations with around 4.3 mmol of formate produced. The presence of proton responsive groups on the catalysts was found to steer the mechanistic cycle away from using a bridged Ir-H-Ir intermediate before forming catalytically active species. In addition, these catalysts were found to hydrogenate CO2 in the presence of bicarbonate ions selectively.
Degradation of Organic Cations under Alkaline Conditions
You, Wei,Hugar, Kristina M.,Selhorst, Ryan C.,Treichel, Megan,Peltier, Cheyenne R.,Noonan, Kevin J. T.,Coates, Geoffrey W.
supporting information, p. 254 - 263 (2020/12/23)
Understanding the degradation mechanisms of organic cations under basic conditions is extremely important for the development of durable alkaline energy conversion devices. Cations are key functional groups in alkaline anion exchange membranes (AAEMs), and AAEMs are critical components to conduct hydroxide anions in alkaline fuel cells. Previously, we have established a standard protocol to evaluate cation alkaline stability within KOH/CD3OH solution at 80 °C. Herein, we are using the protocol to compare 26 model compounds, including benzylammonium, tetraalkylammonium, spirocyclicammonium, imidazolium, benzimidazolium, triazolium, pyridinium, guanidinium, and phosphonium cations. The goal is not only to evaluate their degradation rate, but also to identify their degradation pathways and lead to the advancement of cations with improved alkaline stabilities.
