A Nontrigonal Tricoordinate Phosphorus Ligand Exhibiting Reversible “Nonspectator” L/X‐Switching

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim We report here a “nonspectator” behavior for an unsupported L-function σ3-P ligand (i.e. P{N[o-NMe-C6H4]2}, 1a) in complex with the cyclopentadienyliron dicarbonyl cation (Fp+). Treatment of 1a⋅Fp+ with [(Me2N)3S][Me3SiF2] results in fluoride addition to the P-center, giving the isolable crystalline fluorometallophosphorane 1aF⋅Fp that allows a crystallographic assessment of the variance in the Fe−P bond as a function of P-coordination number. The nonspectator reactivity of 1a⋅Fp+ is rationalized on the basis of electronic structure arguments and by comparison to trigonal analogue (Me2N)3P⋅Fp+ (i.e. 1b⋅Fp+), which is inert to fluoride addition. These observations establish a nonspectator L/X-switching in (σ3-P)–M complexes by reversible access to higher-coordinate phosphorus ligand fragments

Insertion of a Nontrigonal Phosphorus Ligand into a Transition Metal-Hydride: Direct Access to a Metallohydrophosphorane

The synthesis and reactivity of an NPN-chelating ligand containing a nontrigonal phosphorous triamide center (L1 = P(N(o-N(2-pyridyl)C₆H₄)₂) is reported. Metalation of L1 with RuCl2(PPh₃)₃ gives RuCl2(PPh₃)(L1) (2). By contrast, metalation of L1 with RuHCl(CO)(PPh₃)₃ yields RuCl(CO)(PPh₃)(L1[superscript H]) (3), a chelated 10-P-5 ruthenahydridophosphorane, via net insertion into the Ru–H bond. Hydride abstraction from 3 with Ph₃CPF₆ gives [RuCl(CO)(PPh₃)(L1)]PF₆ (4); reaction of 4 with NaBH₄ returns 3.National Institutes of Health (U.S.) (Grant GM114547)National Science Foundation (Grant CHE-1724505

Tetragonal phosphorus(v) cations as tunable and robust catalytic Lewis acids

The synthesis and catalytic reactivity of a class of water-tolerant cationic phosphorus-based Lewis acids is reported. Corrole-based phosphorus(v) cations of the type [ArP(cor)][B(C[subscript 6]F[subscript 5])[subscript 4]] (Ar = C[subscript 6]H[subscript 5], 3,5-(CF[subscript 3])[subscript 2]C[subscript 6]H[subscript 3]; cor = 5,10,15-(C[subscript 6]H[subscript 5])[subscript 3]corrolato[superscript 3-], 5,10,15-(C[subscript 6]F[subscript 5])[subscript 3]corrolato[superscript 3-]) were synthesized and characterized by NMR and X-ray diffraction. The visible electronic absorption spectra of these cationic phosphacorroles depend strongly on the coordination environment at phosphorus, and their Lewis acidities are quantified by spectrophotometric titrations. DFT analyses establish that the character of the P-acceptor orbital comprises P-N antibonding interactions in the basal plane of the phosphacorrole. Consequently, the cationic phosphacorroles display unprecedented stability to water and alcohols while remaining highly active and robust Lewis acid catalysts for carbonyl hydrosilylation, C[subscript sp3]-H bond functionalization, and carbohydrate deoxygenation reactions

Chemoselective Primary Amination of Aryl Boronic Acids by P-III/P-V=O-Catalysis: Synthetic Capture of the Transient Nef Intermediate HNO

A catalytic approach to intercept the transient HNO for a chemoselective primary amination of arylboronic acids isreported. A phosphetane-based catalyst operating within PIII/PV???O redox cycling is shown to capture HNO, generated in situ byNef decomposition of 2-nitropropane, to selectively install the primary amino group at aryl Csp2centers. The method furnishesversatile primary arylamines from arylboronic acid substrates with the preservation of otherwise reactive functional groupsN

P(III)/P(V)-Catalyzed Methylamination of Arylboronic Acids and Esters: Reductive C–N Coupling with Nitromethane as a Methylamine Surrogate

Copyright © 2020 American Chemical Society. The direct reductive N-arylation of nitromethane by organophosphorus-catalyzed reductive C-N coupling with arylboronic acid derivatives is reported. This method operates by the action of a small ring organophosphorus-based catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide) together with a mild terminal reductant hydrosilane to drive the selective installation of the methylamino group to (hetero)aromatic boronic acids and esters. This method also provides for a unified synthetic approach to isotopically labeled N-methylanilines from various stable isotopologues of nitromethane (i.e., CD3NO2, CH315NO2, and 13CH3NO2), revealing this easy-to-handle compound as a versatile precursor for the direct installation of the methylamino group

Addition Reactions of a Phosphorus Triamide to Nitrosoarenes and Acylpyridines

Tricoordinate phosphorus compounds react with a wide variety of double bonds through addition reactions. The dipolar and cyclic products formed are important intermediates in organophosphorus chemistry. We investigated the reactivity between phosphorus triamide 1 and nitrosoarenes and 2-acylpyridines. For sterically congested substrates, the formation of σ5,λ5-phosphorus products is observed. DFT calculations indicate this product is formed through a concerted [4 + 1] mechanism. For less sterically congested substrates, products are observed arising from cleavage of the N = O or C = O bond with formation of a terminal P = O bond and aryl nitrene or carbene migration into a P–N bond of the phosphorus triamide core. DFT calculations are consistent with an initial [2 + 1] addition to phosphorus followed by formal carbene/nitrene migration in these cases

Main Group Redox Catalysis of Organopnictogens: Vertical Periodic Trends and Emerging Opportunities in Group 15

© 2021 American Chemical Society. A growing number of organopnictogen redox catalytic methods have emerged - especially within the past 10 years - that leverage the plentiful reversible two-electron redox chemistry within Group 15. The goal of this Perspective is to provide readers the context to understand the dramatic developments in organopnictogen catalysis over the past decade with an eye toward future development. An exposition of the fundamental differences in the atomic structure and bonding of the pnictogens, and thus the molecular electronic structure of organopnictogen compounds, is presented to establish the backdrop against which organopnictogen redox reactivity - and ultimately catalysis - is framed. A deep appreciation of these underlying periodic principles informs an understanding of the differing modes of organopnictogen redox catalysis and evokes the key challenges to the field moving forward. We close by addressing forward-looking directions likely to animate this area in the years to come. What new catalytic manifolds can be developed through creative catalyst and reaction design that take advantage of the intrinsic redox reactivity of the pnictogens to drive new discoveries in catalysis

Insertion of a Nontrigonal Phosphorus Ligand into a Transition Metal-Hydride: Direct Access to a Metallohydrophosphorane

The synthesis and reactivity of an NPN-chelating ligand containing a nontrigonal phosphorous triamide center (<b>L1</b> = P­(N­(<i>o</i>-N­(2-pyridyl)­C₆H₄)₂) is reported. Metalation of <b>L1</b> with RuCl₂(PPh₃)₃ gives RuCl₂(PPh₃)­(<b>L1</b>) (<b>2</b>). By contrast, metalation of <b>L1</b> with RuHCl­(CO)­(PPh₃)₃ yields RuCl­(CO)­(PPh₃)­(<b>L1</b>^H) (<b>3</b>), a chelated 10-P-5 ruthenahydridophosphorane, via net insertion into the Ru–H bond. Hydride abstraction from <b>3</b> with Ph₃CPF₆ gives [RuCl­(CO)­(PPh₃)­(<b>L1</b>)]­PF₆ (<b>4</b>); reaction of <b>4</b> with NaBH₄ returns <b>3.</b