Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts

Abstract

The replacement of noble metal technologies and the realization of new reactivities with earth‐abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron‐catalyzed hydrogenation protocol for tri‐ and tetra‐substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.

Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst

“…Our recent investigationsi nto the development of low-valent Fe catalysts documented the especially high activity of FeX 2 /DIBAL-H (DIBAL-H = diisobutylaluminum hydride) catalyst mixtures in alkene hydrogenations. [11] At higherD IBAL-H concentrations, the Fe catalysts rapidly formed black suspensions, which efficiently catalyzed the complete hydrogenation to the alkane (entries 1, 3,5,9,10). At al ower DIBAL-Hc oncentration, Fe(hmds) 2 was an active catalystofthe [2+ +2+ +2]-cyclotrimerization to the benzene derivatives.…”

Synthesis and Reactivity of an Early‐Transition‐Metal Alkynyl Cubane Mn4C4 Cluster

“…[5,6] Catalytic applications,however,have largely been neglected. [8][9][10] This approach enabled the synthesis of discrete Mn 6 ,Fe 4 ,Fe 6 ,and Fe 7 clusters that exhibited planar geometries (Scheme 2). [8][9][10] This approach enabled the synthesis of discrete Mn 6 ,Fe 4 ,Fe 6 ,and Fe 7 clusters that exhibited planar geometries (Scheme 2).…”

“…[6,7] Our research group and Ohki and coworkers have successfully implemented m 2 -amido and m 3hydrido ligands for the stabilization of various novel nanocluster architectures. [9,10] Alkyne ligands constitute ad istinct and versatile class of ligands for the design of metal cluster architectures.T hey offer various coordination modes (s, p 2 , p 4 ;t erminal and bridging), are competent stabilizers of atomically precise nanoclusters,a nd provide the opportunity for facile removal or ligand exchange under mild conditions. [9,10] Alkyne ligands constitute ad istinct and versatile class of ligands for the design of metal cluster architectures.T hey offer various coordination modes (s, p 2 , p 4 ;t erminal and bridging), are competent stabilizers of atomically precise nanoclusters,a nd provide the opportunity for facile removal or ligand exchange under mild conditions.…”

Synthesis and Reactivity of an Early‐Transition‐Metal Alkynyl Cubane Mn4C4 Cluster

“…[6,7] Our research group and Ohki and coworkers have successfully implemented m 2 -amido and m 3hydrido ligands for the stabilization of various novel nanocluster architectures. [8][9][10] This approach enabled the synthesis of discrete Mn 6 ,Fe 4 ,Fe 6 ,and Fe 7 clusters that exhibited planar geometries (Scheme 2). [9,10] Alkyne ligands constitute ad istinct and versatile class of ligands for the design of metal cluster architectures.T hey offer various coordination modes (s, p 2 , p 4 ;t erminal and bridging), are competent stabilizers of atomically precise nanoclusters,a nd provide the opportunity for facile removal or ligand exchange under mild conditions.…”

“…[8][9][10] This approach enabled the synthesis of discrete Mn 6 ,Fe 4 ,Fe 6 ,and Fe 7 clusters that exhibited planar geometries (Scheme 2). [9,10] Alkyne ligands constitute ad istinct and versatile class of ligands for the design of metal cluster architectures.T hey offer various coordination modes (s, p 2 , p 4 ;t erminal and bridging), are competent stabilizers of atomically precise nanoclusters,a nd provide the opportunity for facile removal or ligand exchange under mild conditions. [11, 12b] Stable alkynyl clusters of the coinage metals (Cu, Ag, Au), which benefit from the soft carbophilicity of the Group 11 metals,have most often been prepared, and their photophysical properties and catalytic activities studied (Scheme 1).…”