Low-Valent Transition Metalate Anions in Synthesis, Small Molecule Activation, and Catalysis

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(4), P. 1323 - 1463

Published: Feb. 14, 2024

This review surveys the synthesis and reactivity of low-oxidation state metalate anions d-block elements, with an emphasis on contributions reported between 2006 2022. Although field has a long rich history, chemistry transition been greatly enhanced in last 15 years by application advanced concepts complex ligand design. In recent years, potential highly reactive complexes fields small molecule activation homogeneous catalysis become increasingly evident. Consequently, exciting applications have developed, including catalytic transformations. article intends to guide reader through fascinating world low-valent metalates. The first part describes metalates stabilized assortment frameworks, carbonyls, isocyanides, alkenes polyarenes, phosphines phosphorus heterocycles, amides, redox-active nitrogen-based ligands. Thereby, will be familiarized impact different types physical chemical properties addition, ion-pairing interactions metal–metal bonding may dramatic influence structures reactivities. ramifications these effects are examined separate section. second is devoted toward inorganic molecules such as H2, N2, CO, CO2, P4 related species. It shown that use electron-rich translates into impressive hydrogenation organic reduction CO2. results discussed this illustrate being tapped for challenging processes relevance energy conversion. Therefore, it hoped serve useful resource inspire further developments dynamic research field.

Language: Английский

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Stereodivergent, Kinetically Controlled Isomerization of Terminal Alkenes via Nickel Catalysis

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(21)

Published: March 18, 2024

Abstract Because internal alkenes are more challenging synthetic targets than terminal alkenes, metal‐catalyzed olefin mono‐transposition (i.e., positional isomerization) approaches have emerged to afford valuable E ‐ or Z‐ from their complementary alkene feedstocks. However, the applicability of these methods has been hampered by lack generality, commercial availability precatalysts, and scalability. Here, we report a nickel‐catalyzed platform for stereodivergent / Z ‐selective synthesis at room temperature. Commercial reagents enable this one‐carbon transposition ‐internal via Ni−H‐mediated insertion/elimination mechanism. Though mechanistic regime is same in both systems, underlying pathways that lead each active catalysts distinct, with catalyst forming comproportionation an oxidative addition complex followed substrate protonation metal trialkylphosphonium salt additive. In case, ligand sterics denticity control stereochemistry prevent over‐isomerization.

Language: Английский

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Spin effect on redox acceleration and regioselectivity in Fe-catalyzed alkyne hydrosilylation

National Science Review, Journal Year: 2023, Volume and Issue: 11(2)

Published: Dec. 19, 2023

ABSTRACT Iron catalysts are ideal transition metal because of the Earths abundant, cheap, biocompatible features iron salts. often have unique open-shell structures that easily undergo spin crossover in chemical transformations, a feature rarely found noble catalysts. Unfortunately, little is known currently about how structure and affect reactivity selectivity catalysts, which makes development low efficient trial-and-error program. In this paper, combination experiments theoretical calculations revealed iron-catalyzed hydrosilylation alkynes typical spin-crossover catalysis. Deep insight into electronic set well-defined active formal Fe(0) spin-delocalization between center 1,10-phenanthroline ligand effectively regulates center's oxidation state to meet opposite electrostatic requirements oxidative addition reductive elimination, respectively, essential for electron transfer process. The triplet was achieving high regioselectivity through tuning nonbonding interactions. These findings provide an important reference understanding effect catalyst on reaction. It inspiring other Earth-abundant especially from point view development.

Language: Английский

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Catalytic 1,3-Proton Transfer in Alkenes Enabled by Fe═NR Bond Cooperativity: A Strategy for pK_a-Dictated Regioselective Transposition of C═C Double Bonds

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(22), P. 11978 - 11987

Published: May 25, 2023

Transition metal catalyzed alkene double bond transposition usually involves hydride intermediates. Despite significant advances in the design of catalysts that dictate product selectivity, control over substrate selectivity is less advanced and transition selectively transpose bonds substrates containing multiple 1-alkene functionalities are rare. Herein, we report three-coordinate high spin (S = 2) Fe(II) imido complex [Ph2B(tBuIm)2Fe═NDipp][K(18-C-6)THF2] (1-K(18-C-6)) catalyzes 1,3-proton transfer from to afford 2-alkene products. Mechanistic investigations involving kinetics, competition, isotope labeling studies, supported by experimentally calibrated DFT computations, strongly support an unusual nonhydridic mechanism for enabled cooperative action iron center basic ligand. As dictated pKa allylic protons, this catalyst enables regioselective C═C 1-alkenes. The state allows a wide scope functional groups be tolerated, including those typical poisons, such as amines, N-heterocycles, phosphines. These results demonstrate new strategy metal-catalyzed with predictable regioselectivity.

Language: Английский

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Switching between Hydrogenation and Olefin Transposition Catalysis via Silencing NH Cooperativity in Mn(I) Pincer Complexes

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(17), P. 10818 - 10825

Published: Aug. 19, 2022

While Mn-catalyzed (de)hydrogenation of carbonyl derivatives has been well established, the reactivity Mn hydrides with olefins remains very rare. Herein, we report a Mn(I) pincer complex that effectively promotes site-controlled transposition olefins. This is shown to emerge once N-H functionality within Mn/NH bifunctional suppressed by alkylation. detrimental for (de)hydrogenation, such masking cooperative allows highly efficient conversion wide range allylarenes higher-value 1-propenybenzenes in near-quantitative yield excellent stereoselectivities. The toward single positional isomerization was also retained long-chain alkenes, resulting regioselective formation 2-alkenes, which are less thermodynamically stable compared other possible products. detailed mechanistic analysis reaction between activated catalyst and points catalysis operating via metal-alkyl mechanism-one three conventional mechanisms previously unknown complexes.

Language: Английский

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Iron‐Catalyzed Positional and Geometrical Isomerization of Alkenes

Advanced Synthesis & Catalysis, Journal Year: 2023, Volume and Issue: 365(8), P. 1100 - 1111

Published: Feb. 20, 2023

Abstract This review outlines the most noteworthy achievements of last few years in renascent field positional and geometrical isomerization alkenes using iron catalysis, from a mechanistic perspective. Particular attention will be placed on developments beyond seminal contributions carbonyl complexes their aspects underlying nature active species. The relevant literature has been covered until late 2022. magnified image

Language: Английский

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Iron‐Catalyzed Allylic C(sp³)−H Silylation: Spin‐Crossover‐Efficiency‐Determined Chemoselectivity

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(21)

Published: March 12, 2024

Abstract The nuanced role of spin effects remains a critical gap in designing proficient open‐shell catalysts. This study elucidates an iron‐catalyzed allylic C( sp 3 )−H silylation/alkyne hydrosilylation reaction, which the state iron catalyst dictates reaction kinetics and pathway. Specifically, crossover led to alkyne hydrosilylation, whereas conservation resulted novel silylation reaction. chemoselectivity, governed by spin‐crossover efficiency, reveals unexpected dimension first realm transition‐metal‐catalyzed situ bonds, had been previously inhibited heightened reactivity alkenes reactions. Furthermore, this can either accelerate or hinder at different stages within single catalytic phenomenon scarcely documented. Moreover, we identify substrate‐assisted C−H activation mechanism, departure from known ligand‐assisted processes, offering fresh perspective on strategies.

Language: Английский

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N-heterocyclic carbenes as bridgehead donors in metal pincer complexes

Coordination Chemistry Reviews, Journal Year: 2024, Volume and Issue: 514, P. 215757 - 215757

Published: May 9, 2024

Language: Английский

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α-Methylation of Ketones and Indoles Catalyzed by a Manganese(I) PC_NHCP Pincer Complex with Methanol as a C₁ Source

Organometallics, Journal Year: 2022, Volume and Issue: 42(1), P. 62 - 71

Published: Dec. 28, 2022

Acceptorless alcohol dehydrogenation is a powerful reaction in sustainable synthesis. When combined tandem with dehydrogenative coupling or hydrogen borrowing, acceptorless can be used for the environmentally benign construction of C–C, C–N, and C–O bonds. While many these reactions rely on using precious metals, past decade use earth-abundant metals has become more prevalent. If green renewable feedstock could introduced as well, sustainability further increased. Methanol would such substrate serve C1 source when methylation wide variety substrates. Herein, we report efficient manganese-catalyzed α-methylation ketones indoles. The manganese catalyst based PCNHCP pincer platform containing rare central carbene donor. supports diverse set functional groups, occurs at moderate temperatures (110 °C), provides corresponding methylated indoles excellent yields. In contrast to previously reported mechanisms, herein mechanism does not depend metal–ligand cooperativity but rather proceeds via (i) metal-based featuring hydride (ii) ligand-centered where manganese-carbonyl acts catalytic center, depending additive.

Language: Английский

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Unparalleled Dimerization of Trans-2-Butene to 3,4-Dimethyl-1-Hexene on Iron-Based Catalyst

Published: Jan. 1, 2025

Language: Английский

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