Reactivity umpolung (reversal) of ligands in transition metal complexes

Chemical Society Reviews, Год журнала: 2024, Номер 53(6), С. 2808 - 2827

Опубликована: Янв. 1, 2024

The power of transition metal ions and their ligands to reverse the native reactivity small molecules is highlighted by providing examples for 15 classes including types L, XL, X, X 2 , 3 .

Язык: Английский

---

Balancing the Seesaw in Mn-Catalyzed N-Heteroarene Hydrogenation: Mechanism-Inspired Catalyst Design for Simultaneous Taming of Activation and Transfer of H₂

ACS Catalysis, Год журнала: 2023, Номер 13(7), С. 4824 - 4834

Опубликована: Март 27, 2023

Recently, Mn-catalyzed hydrogenation reactions have gained significant interest due to their importance in various challenging transformations. Among several classes of organic substrates, including amides, ketones, carbamates, urea-derivatives, (cyclic) carbonates/polycarbonates, CO2, and CO2 derivatives, N-heteroarene using a Mn-based system is severely underdeveloped. Only handful reports are known the literature, which mainly use expensive phosphine-based ligand systems for designing effective Mn catalysts. Mechanistically, pincer catalysts, H2-activation step was facilitated by typical metal–ligand bifunctional mechanism through so-called "Mn-amino"/"Mn-amido" platform, while H2-transfer (in form hydride proton transfer) triggered judiciously designed stereoelectronically tuned P- and/or N-donor ligands attached at center. Interestingly, these two steps, i.e., H2-transfer, often counteract owing opposite stereoelectronic demands metal center, existing PNP-Mn NNP-Mn catalysts indeed suffer from disbalanced energetics case steps. With rationally analyzed approach, herein, we show how crucial steps can be simultaneously tamed balanced optimize kinetic thermodynamic demand. Thus, exchange both P N arms PNP/NNP framework with better σ-donor, moderate π-acceptor, sterically nonhindering planar such as N-heterocyclic carbenes (NHCs), keeping central amino/amido-based H2-activating motif intact, critical catalytic cycle reducing corresponding activation barriers balancing stability Mn-hydride species (ΔG# H2-cleavage: 19.2 kcal/mol; ΔG# H2 (hydride/proton)-transfer: 22.2 ΔG H2-cleavage step: −2.8 kcal/mol). Eventually, bis-NHC-armed CNC-Mn catalyst, mechanism-inspired proved apt efficient variety N-heteroarenes, under 10–60 bar pressure 60–120 °C temperature within 6–12 h reaction time.

Язык: Английский

---

Base-Free Reversible Hydrogen Storage Using a Tethered π-Coordinated-Phenoxy Ruthenium-Dimer Precatalyst

ACS Catalysis, Год журнала: 2023, Номер 13(9), С. 5787 - 5794

Опубликована: Апрель 13, 2023

A dimeric tethered π-coordinated-phenoxy ruthenium precatalyst has been used for the base-free hydrogenation of CO2 in DMSO. The same was also efficient reverse dehydrogenation formic acid yet under conditions. An unprecedented cycle consisting hydrogen storage and release successfully implemented with precatalyst. latent property catalyst introduced concept storage/transportation/release.

Язык: Английский

---

Carbon neutral hydrogen storage and release cycles based on dual-functional roles of formamides

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Июнь 22, 2023

The development of alternative clean energy carriers is a key challenge for our society. Carbon-based hydrogen storage materials are well-suited to undergo reversible (de)hydrogenation reactions and the catalysts individual process steps crucial. In current state, noble metal-based still dominate this field. Here, system partially carbon-neutral release reported. It based on dual-functional roles formamides uses small molecule Fe-pincer complex as catalyst, showing good stability reusability with high productivity. Starting from formamides, quantitative production CO-free achieved at selectivity ( > 99.9%). This works modest temperatures 90 °C, which can be easily supplied by waste heat e.g., proton-exchange membrane fuel cells. Employing such system, we achieve >70% H2 evolution efficiency >99% in 10 charge-discharge cycles, avoiding undesired carbon emission between cycles.

Язык: Английский

---

NNN manganese complex-catalyzed α-alkylation of methyl ketones using alcohols: an experimental and computational study

Dalton Transactions, Год журнала: 2024, Номер 53(7), С. 3236 - 3243

Опубликована: Янв. 1, 2024

A quinoline-based pincer Mn catalyst for α-alkylation of methyl ketones using primary alcohols as alkyl surrogates is presented. The C–C bond formation reaction proceeds via a hydrogen auto-transfer protocol, generating water the only by-product.

Язык: Английский

---

Highly efficient hydrogenation of carbamates catalyzed by pincer ruthenium complexes

Journal of Catalysis, Год журнала: 2023, Номер 428, С. 115165 - 115165

Опубликована: Окт. 14, 2023

Язык: Английский

---

Ethanol as hydrogen donor: An efficient transfer hydrogenation of aldehydes, ketones, and nitroarenes with H-bonded Ru(II)-N-heterocyclic iminium complex

Journal of Catalysis, Год журнала: 2023, Номер 429, С. 115207 - 115207

Опубликована: Ноя. 20, 2023

Язык: Английский

---

Utilising a Proton‐Responsive 1,8‐Naphthyridine Ligand for the Synthesis of Bimetallic Palladium and Platinum Complexes

Chemistry - An Asian Journal, Год журнала: 2024, Номер 19(3)

Опубликована: Янв. 1, 2024

Abstract We present four proton‐responsive palladium and platinum complexes, [MCl 2 ( R PONNHO)] (M=Pd, Pt; R= i Pr, t Bu) synthesised by complexation of PdCl or PtCl (COD) with the 1,8‐naphthyridine ligand PONNHO. Deprotonation tBu switches coordination from mono‐ to dinucleating, offering a synthetic pathway bimetallic Pd II Pt complexes [M Cl PONNO) ]. Two‐electron reduction gives planar M I −M ] Pt) containing metal‐metal bond. In contrast related nickel system that forms metallophosphorane [Ni PONNOPONNO)], an unusual phosphinite binding mode is observed in close phosphinite‐naphthyridinone P⋅⋅⋅O interactions, which investigated spectroscopically, crystallographically computationally. The presented structurally‐responsive PONNHO PONNO offer novel platform for future explorations metal‐ligand cooperativity platinum.

Язык: Английский

---

Ambient-pressure selective hydrogenation of unsaturated aldehydes and ketones into unsaturated alcohols in the water phase

Dalton Transactions, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

N -Functionalized amino ligand-stabilized ruthenium complexes catalyze the hydrogenation of unsaturated carbonyl derivatives into corresponding alcohols with CC bonds retained under ambient H 2 pressure in water.

Язык: Английский

---

A well-defined phosphine free metal-ligand cooperative route for N-alkylation of aromatic amines via activation of renewable alcohols catalyzed by a NNN pincer cobalt(II) complexes

Dalton Transactions, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Two cobalt( ii ) complexes C1 and C2, supported by an NNN pincer, were synthesized, characterized with various techniques. These utilized to study catalytic activity in the N -alkylation of amines via borrowing hydrogen strategy.

Язык: Английский

---