Interconversion of CO2/H2 and Formic Acid Under Mild Conditions in Water

Cobalt Single-Atom Catalysts with High Stability for Selective Dehydrogenation of Formic Acid

Metal-organic framework (MOF)-derived Co-N-C catalysts with isolated single cobalt atoms have been synthesized and compared with cobalt nanoparticles for formic acid dehydrogenation. The atomically dispersed Co-N-C catalyst achieves superior activity, better acid resistance, and improved long-term stability compared with nanoparticles synthesized by a similar route. High-angle annular dark-field-scanning transmission electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and X-ray absorption fine structure characterizations reveal the formation of CoII Nx centers as active sites. The optimal low-cost catalyst is a promising candidate for liquid H2 generation.

Insertion of CS2into the Mg–H bond: synthesis and structural characterization of the magnesium dithioformate complex, [TismPriBenz]Mg(κ2-S2CH)

Insertion of CS₂into the Mg–H bond of [Tism^PriBenz]MgH affords [Tism^PriBenz]Mg(κ²-S₂CH), the first structurally characterized magnesium dithioformate compound.

Hydrogenation of CO2 to formic acid with iridiumIII(bisMETAMORPhos)(hydride): the role of a dormant fac-IrIII(trihydride) and an active trans-IrIII(dihydride) species

Catalytic hydrogenation of CO₂ to formate with an Ir^III(METAMORPhos) complex in the presence of DBU requires a trans-dihydride for catalytic turnover, with an off-cycle trihydride as the dormant species.

RuIII-edta (edta4− = ethylenediaminetetraacetate) mediated photocatalytic conversion of bicarbonate to formate over visible light irradiated non-metal doped TiO2 semiconductor photocatalysts

[Ru^III(edta)] mediates the conversion of bicarbonate to formate via formation of a [Ru^III(edta)(HCO₃)]²⁻ which undergoes photocatalytic reduction at the conduction band of the visible light irradiated non-metal doped TiO₂ semiconductor particles.

A Highly Efficient Heterogenized Iridium Complex for the Catalytic Hydrogenation of Carbon Dioxide to Formate

A heterogenized catalyst on a highly porous covalent triazine framework was synthesized and characterized to have a coordination environment similar to that of its homogeneous counterpart. The catalyst efficiently converted CO2 into formate through hydrogenation with a turnover number of 5000 after 2 h and an initial turnover frequency of up to 5300 h(-1) ; both of these values are the highest reported to date for a heterogeneous catalyst, which makes it attractive toward industrial application. Furthermore, the synthesized catalyst was found to be stable in air and was recycled by simple filtration without significant loss of catalytic activity.

Domino Hydrogenation-Reductive Amination of Phenols, a Simple Process To Access Substituted Cyclohexylamines

Phenols can be efficiently reduced by sodium formate and Pd/C as the catalyst in water and in the presence of amines to give the corresponding cyclohexylamines. This reaction works at rt for 12 h or at 60 °C under microwave dielectric heating for 20 min. With the exception of aniline, primary, secondary amines, amino alcohols, and even amino acids can be used as nucleophiles. The reductive process is based on a sustainable hydrogen source and a catalyst that can be efficiently recovered and reused. The protocol was developed into a continuous-flow production of cyclohexylamines in gram scale achieving very efficient preliminary results (TON 32.7 and TOF 5.45 h(-1)).

Dehydrogenation, disproportionation and transfer hydrogenation reactions of formic acid catalyzed by molybdenum hydride compounds

The cyclopentadienyl molybdenum hydride compounds, CpRMo(PMe3)3-x (CO) x H (CpR = Cp, Cp*; x = 0, 1, 2 or 3), are catalysts for the dehydrogenation of formic acid, with the most active catalysts having the composition CpRMo(PMe3)2(CO)H. The mechanism of the catalytic cycle is proposed to involve (i) protonation of the molybdenum hydride complex, (ii) elimination of H2 and coordination of formate, and (iii) decarboxylation of the formate ligand to regenerate the hydride species. NMR spectroscopy indicates that the nature of the resting state depends on the composition of the catalyst. For example, (i) the resting states for the CpMo(CO)3H and CpMo(PMe3)(CO)2H systems are the hydride complexes themselves, (ii) the resting state for the CpMo(PMe3)3H system is the protonated species [CpMo(PMe3)3H2]+, and (iii) the resting state for the CpMo(PMe3)2(CO)H system is the formate complex, CpMo(PMe3)2(CO)(κ1-O2CH), in the presence of a high concentration of formic acid, but CpMo(PMe3)2(CO)H when the concentration of acid is low. While CO2 and H2 are the principal products of the catalytic reaction induced by CpRMo(PMe3)3-x (CO) x H, methanol and methyl formate are also observed. The generation of methanol is a consequence of disproportionation of formic acid, while methyl formate is a product of subsequent esterification. The disproportionation of formic acid is a manifestation of a transfer hydrogenation reaction, which may also be applied to the reduction of aldehydes and ketones. Thus, CpMo(CO)3H also catalyzes the reduction of a variety of ketones and aldehydes to alcohols by formic acid, via a mechanism that involves ionic hydrogenation.