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Electrocatalytic hydrogen evolution reaction (eHER) is crucial in addressing the growing global energy demand. Although nickel‐pincer‐based molecular complexes, varying in donor atoms, were studied previously for eHER, the impact of variations in the substituents attached to the donor atoms was not investigated. Herein, three air‐stable R1PN3PR2‐based NiII–pincer complexes [R1=R2=Ph2 (7); R1=R2=tBu2 (9); R1=tBu2, R2=Ph2 (10)], varying solely in P‐substituents, were studied in acetonitrile. While the redox potentials for NiII/I and NiI/0 couples underwent anodic shifts by ~100 mV upon progressively substituting tert‐butyl by phenyl groups on each P‐atom, the corresponding eHER reactivity with organic acids (acetic acid, p‐toluenesulfonic acid and trifluoromethanesulfonic acid) of different strengths followed different trends; likely influenced by the pKa of intermediate metal‐hydride (M–H) species [pKa(M–H9)>pKa(M–H10)>pKa(M–H7)]. Depending on the acid strength, different oxidation states of the metal were activated to promote eHER. The catalytic rates for 9, 10, and 7 were calculated to be 85 s−1, 77 s−1 and 95 s−1 with Faradaic efficiencies of 88.5±2 %, 66.1±1.4 %, and 91.7±1.5 % respectively, in acetic acid. Electrochemical data supported by theoretical results reinforce a significant electronic influence of the anchoring P‐substituents on the activity of these complexes. [ABSTRACT FROM AUTHOR]

The N‐formylation of amines using CO2 hydrogenation, conducted under additive‐free conditions, represents a crucial methodology in organic synthesis. Herein, we demonstrated a highly efficient ruthenium pincer complex for the selective conversion of a wide array of amines into their corresponding formamides under additive‐free condition with a turnover number (TON) of 980,000 within a single‐batch. Controlled studies suggested the initial reduction of CO2 to ammonium formate, followed by dehydration to generate formamide. NMR experiments revealed the potential intermediates and indicated the involvement of metal‐ligand cooperativity of catalyst during substrate activation. In addition, this methodology was examined to establish a carbon neutral hydrogen storage cycle by capitalizing on the reversible transformation of formamides. [ABSTRACT FROM AUTHOR]

The growing emphasis on sustainable chemistry has driven research into utilizing carbon dioxide (CO2) as a nontoxic, abundant, and cost‐effective C1 building block. CO2 offers a promising avenue for direct conversion into valuable chemicals ranging from fuels to pharmaceuticals. This review focuses on the utilization of CO2 for reductive N‐formylation/N‐methylation reactions of various amines, providing advantages over conventional methods involving toxic CO and other methylating reagents. The approach employs readily available reductants such as silane, borane reagents, and hydrogen (H2). The discussion encompasses recent developments in transition metal and organocatalyst systems for these reactions, highlighting mechanistic interpretations and factors influencing product selectivity. [ABSTRACT FROM AUTHOR]

The highly efficient reductive amination of aldehydes with ammonia (NH3) and hydrogen (H2) to form secondary imines is described, as well as the dehydrogenative homocoupling of benzyl amines. Using an air-stable, well-defined PN3-manganese(II) pincer complex as a catalyst precursor, various aldehydes are easily converted directly into secondary imines using NH3 as a nitrogen source under H2 in a one-pot reaction. Importantly, the same catalyst facilitates the dehydrogenative homocoupling of various benzylamines, exclusively forming imine products. These reactions are conducted under very mild conditions, without the addition of any additives, yielding excellent selectivities and high yields of secondary imines in a green manner by minimizing wastes. [ABSTRACT FROM AUTHOR]

This study investigates the phonetic outcome of mixed-language speech in Bengali and Indian English, towards understanding cross-language interaction in highly proficient bilinguals. We compare spectral properties of L2 vowels [æ] (common to L1, L2) and [ʌ] (absent in L1) in code-switched (mixed) vs. nonswitched productions. Results reveal asymmetrical shifts in both vowels during mixed productions, towards related L1 categories. We interpret this as a temporary increase in cross-language phonetic interaction during mixed-language use, leading to a shift towards L1 norms, evidencing transfer effects on L2 vowels. We elicit mixed productions through two tasks: cued picture-naming and code-switching, to assess if experimental paradigm independently influences the behavior under study. Results reveal parallel patterns, but small magnitude differences, across paradigms. We discuss these findings in light of recent proposals about asymmetries in short-term phonetic interaction, postulated discursive factors in code-switching, and the issue of comparability between paradigms in transfer studies. [ABSTRACT FROM AUTHOR]

Well-defined and air-stable PN3–pincer manganese(II) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the C＝C double bond/C≡C triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively. [ABSTRACT FROM AUTHOR]

Formic acid (FA) has emerged as a promising candidate for hydrogen energy storage due to its favorable properties such as low toxicity, low flammability, and high volumetric hydrogen storage capacity under ambient conditions. Recent analyses have suggested that FA produced by electrochemical carbon dioxide (CO 2 ) reduction reaction (eCO 2 RR) using low-carbon electricity exhibits lower fugitive hydrogen (H 2 ) emissions and global warming potential (GWP) during the H 2 carrier production, storage and transportation processes compared to those of other alternatives like methanol, methylcyclohexane, and ammonia. eCO 2 RR to FA can enable industrially relevant current densities without the need for high pressures, high temperatures, or auxiliary hydrogen sources. However, the widespread implementation of eCO 2 RR to FA is hindered by the requirement for highly stable and selective catalysts. Herein, the aim is to explore and evaluate the potential of catalyst engineering in designing stable and selective nanostructured catalysts that can facilitate economically viable production of FA., (© 2024 Wiley‐VCH GmbH.)

The highly efficient reductive amination of aldehydes with ammonia (NH 3 ) and hydrogen (H 2 ) to form secondary imines is described, as well as the dehydrogenative homocoupling of benzyl amines. Using an air-stable, well-defined PN 3 -manganese(II) pincer complex as a catalyst precursor, various aldehydes are easily converted directly into secondary imines using NH 3 as a nitrogen source under H 2 in a one-pot reaction. Importantly, the same catalyst facilitates the dehydrogenative homocoupling of various benzylamines, exclusively forming imine products. These reactions are conducted under very mild conditions, without the addition of any additives, yielding excellent selectivities and high yields of secondary imines in a green manner by minimizing wastes.

Well-defined and air-stable PN 3 -pincer manganese(II) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.