A Kekulé Diradicaloid with a Naphthalene Spacer

The availability of a diverse array of carbenes led to the generation of a catalog of carbene based Kekulé diradicaloids, but the linker in such molecules is mostly limited to phenylene or biphenylene...

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Magnesium-Catalyzed CO2 Reduction to Formic Acid or Methanol: Solvent or No Solvent Settles the Selectivity

Reducing the carbonyl (C═O) group in carbon dioxide is a difficult yet crucial step for producing valuable chemical compounds. This approach holds promise for creating new methods to utilize nonfossil-based raw materials. Using catalysts made from abundant, inexpensive, and environmentally friendly metals, such as magnesium, could significantly advance the development of sustainable synthetic techniques. In this study, a magnesium pincer compound (1) is shown to facilitate the reduction of CO2 with pinacolborane as the reductant. When used without a solvent, the reaction produces methoxyborane, whereas in THF, it leads to formoxyborane. Formoxyborane has been identified as a “missing link” in homogeneous CO2 reduction by catalysts based on alkaline earth metal elements. The variation in product selectivity was substantiated through DFT calculations. The initial generation of the Mg(II) hydride catalyst both in the absence and presence of THF entails an activation barrier within 25–26 kcal mol–1. However, the rate-determining step, in the absence of a solvent, involves hydride transfer-mediated reduction at the formate fragment accompanying a transition barrier of 27.3 kcal mol–1. In the presence of THF, the rate-determining step involves hydride transfer to the Mg center with a barrier of 29.2 kcal mol–1, generating the catalyst and boryl formate.

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Alkyl Bismuth Cations: Synthesis, Characterization, and Application as Z‐Type Ligands

Rare examples of alkyl bismuth cations [BiR2(SbF6)] are presented, including cyclopropyl ligands and a bismacyclic structure. The bismuth-centered Lewis acids act as Z-type ligands toward the electro....

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Reactivity of Diaryl Bismuth Cations toward a Platinum(0) Complex: Oxidative Aryl Transfer

Reactions of three aryl-substituted bismuth cations, [BiPh2(SbF6)], [BiMes2(SbF6)], and [BiDipp2(SbF6)], with the Pt0 complex Pt(PCy3)2 have been investigated (Mes = 2,4,6-trimethyl-phenyl; Dipp = 2,6-di-iso-propyl-phenyl; Cy = cyclohexyl). Unexpectedly, and in contrast with the reactivity of the recently reported methyl analogue [BiMe2(SbF6)], the formation of isolable metal-only Lewis pairs [(Cy3P)2Pt→BiAr2(SbF6)] is not observed (Ar = aryl). Instead, an unprecedented bismuth-to-platinum oxidative aryl transfer is witnessed to give the PtII complexes [PtAr(PCy3)2(SbF6)], along with the suggested bismuthinidene intermediates BiAr. Attempts to trap these fleeting intermediates with an ortho-quinone led to a PtII semiquinone radical complex.

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Homoleptic Bismuth Alkynes: Isolable Reagents for Selective Alkynyl Radical Transfer

The first series of fully characterized homoleptic alkynyl bismuth compounds Bi(C≡CR)3 is presented. Facile homolytic Bi–C bond cleavage grants access to alkynyl radicals, which have been employed in...

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Diaryl Bismuthides and Acyl Bismuthanes Enable Visible-Light-Induced Reversible Carbon Monoxide Insertion and Extrusion - Nature Communications

Carbon monoxide (CO) is one of the simplest and most fundamental molecules that has fascinated chemists for decades. Early-on, chemists have recognized and exploited its favorable properties as a key ...

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The Methylbismuth Dication: Pentagonal Pyramidal Coordination and Ligand‐Induced Lewis Superacidity

The simplistic methylbismuth dication has been captured only by the aid of monodentate tetrahydrofuran (thf) ligands, [BiMe(thf)5]2+. The hexacoordinate species shows a very unusual pentagonal pyrami...

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Bismuth Radical Catalysis: Thermally Induced Intramolecular C(sp3)–C(sp) Cyclization of Unactivated Alkyl Iodides and Alkynes

Bismuth radical chemistry has attracted increased interest in recent years. Here, we report a series of bismuth–manganese complexes that catalyze the intramolecular redox-neutral coupling of alkyl iod...

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Magnesium-Catalyzed Primary, Secondary, and Tertiary Amide Hydroboration

Catalytic hydroboration of amides is highly important because the resultant amines are commonly found in natural products, pharmaceuticals, agrochemicals, dyes, and other applications. In comparison to the conventional reduction of amides using (over)stoichiometric reductants, hydroboration of amides using magnesium compounds represents a green and sustainable approach because magnesium is both Earth abundant and environmentally benign. However, there is only one report on magnesium-catalyzed deoxygenative hydroboration of secondary and tertiary amides. Here, we describe the synthesis and structural authentication of two new magnesium compounds (1 and 2) featuring a flexible PNP ligand and the utilization of 2 as a catalyst for the pinacolborane-mediated reduction of primary, secondary, and tertiary amides to amines. The reaction scope is explored, and a mechanism is proposed based on experimental and theoretical insights.

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Manganese(I)-catalyzed dehydrogenative borylation of terminal alkynes

Compounds containing carbon–boron bonds serve as valuable intermediates for constructing more complex molecules by transforming these bonds into other carbon–element bonds. The catalytic dehydrogenati...

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Bismuth Meets Olefins: Ethylene Activation and Reversible Alkene Insertion into Bi─N Bonds

Well-defined cationic bismuth compounds have been exposed to simple α-olefins, including the benchmark substrate ethylene. Unprecedented and facile insertion, extrusion, and olefin exchange scenarios....

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The Careful Combination of Bismuth Compounds and CAAC: Formal Halonium and Nitrenium Transfer via Radical Pathways

Fundamental bismuth compounds such as BiCl3 and BiBr(NMe2)2 form simple, colorful adducts with cyclic (alkyl)(amino)carbenes. They undergo facile and selective formal X+ and (NMe2)+ transfer from bis...

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