Cationic Carbene Analogues: Donor‐Free Phosphenium and Arsenium Ions

Olaru, Marian; Mebs, Stefan; Beckmann, Jens

doi:10.1002/anie.202107975

Cited by 21 publications

(41 citation statements)

References 49 publications

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“…For example, compound 4 can be treated with organometallic reagents, such as Grignard and organolithium species, to afford dithienophospholes with a variety of P–R groups ( 5 , 5-O ) (Scheme ). − …”

Section: Enhancing σ*−π* Interactions Through P–p Bond Formationmentioning

confidence: 99%

Unique Phosphorus-Based Avenues for the Tuning of Functional Materials

2023

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Metrics & MoreArticle Recommendations CONSPECTUS: Recent ground-breaking advances in synthetic chemistry have transformed main-group molecules from simple laboratory curiosities into powerful materials for a range of applications in all realms of life. Electron-accepting or -deficient materials, in particular, have been the focus of development since their generally limited availability and stability have been major hurdles in establishing new practical applications. In addition to the general requirements for the design of these materials, a deeper understanding of their inherent electronics and molecular interactions is a requirement for the successful expansion of their utility. Previously, the incorporation of electron-deficient main-group elements, such as boron, into a conjugated organic framework was considered to be an effective route toward the synthesis of high-performing electron-accepting materials. However, challenging conditions such as the need for bulky substituents for kinetic stabilization, air-free and moisture-sensitive synthesis, and restricted storage abilities have led to the investigation of other elements across the periodic table to be used in a similar vein. Lately, heavier main-group elements such as Si, Ge, P, As, Sb, Bi, S, Se, and Te have also proven to be advantageous for electron-accepting materials as they exhibit polarizable molecular orbitals that are easily accessible to electrons or nucleophiles. This has laid the foundation for materials chemistry research on a variety of applications, including optoelectronic devices such as OLEDs, organic photovoltaics, energy storage such as in batteries and capacitors, fluorescent sensors with both biological and physiological applications, organocatalysis and synthesis, and many more. Among the main-group-element-based materials, organophosphorus species are privileged as their frontier orbitals are easily altered by chemical modification or/and structural and geometrical manipulations at the phosphorus center itself, without the need for kinetic stabilization, or through electronic modification of the conjugated system. The five-membered phosphorus-based heterocycle, phosphole, is a particularly interesting motif in this context, and extensive studies on the corresponding materials have uncovered the rich fundamentals of the σ*−π* interaction that imparts intriguing accepting properties while sustaining morphological and physiological stability for utilization in real-life scenarios. Moreover, beyond the σ*−π* interaction in phospholes that is key to many of their acceptor properties as a material, the use of phosphorus also gives rise to easily accessible, low-lying antibonding orbitals. They pave the way for Lewis acid phosphorus species that, despite being considered to be electron-rich species in general, open up several possibilities for intriguing chemical reactivity through hypervalency. Herein, we representatively discuss some recent advancements through the various approaches that leverage the unique structures and electronics...

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Section: Enhancing σ*−π* Interactions Through P–p Bond Formationmentioning

confidence: 99%

Unique Phosphorus-Based Avenues for the Tuning of Functional Materials

2023

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“…In recent years, electron-rich carbon-based substituents like (pentamethyl)cyclopentadienyl or ferrocenyl groups have been employed to tame the reactivity of phosphenium ions, ,, and only very recently, a donor-free, exclusively kinetically stabilized phosphenium ion was isolated by Beckmann et al Non-stabilized, in situ formed phosphenium ions are attractive species, e.g., as building blocks for polyphosphorus compounds, for small molecule activation, , or their ability to act as dienophiles toward 1,3-dienes …”

Section: Introductionmentioning

confidence: 99%

“…3,5,6 However, thermodynamically stabilized phosphenium ions by inter-or intramolecular coordination or N-heterocyclic phosphenium ions of the type [R 2 N−P−NR 2 ] + with π-electron donating groups are less reactive due to reduced electrophilicity. 4,7−9 In recent years, electron-rich carbon-based substituents like (pentamethyl)cyclopentadienyl or ferrocenyl groups have been employed to tame the reactivity of phosphenium ions, 8,10,11 and only very recently, a donor-free, exclusively kinetically stabilized phosphenium ion was isolated by Beckmann et al 12 Non-stabilized, in situ formed phosphenium ions are attractive species, e.g., as building blocks for polyphosphorus com-pounds, for small molecule activation, 6,13 or their ability to act as dienophiles toward 1,3-dienes. 14 Here, we set out to investigate whether flanking phosphanyl units are capable of stabilizing phosphenium centers by πelectron donation.…”

Section: ■ Introductionmentioning

confidence: 99%

Gradual Donor Stabilization of a Transient Ferrocene Bridged Bisphosphanyl Phosphenium Cation

et al. 2023

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A transient phosphenium cation embedded into a [3]ferrocenophane scaffold was formed via chloride abstraction. The cation has been trapped with phosphane, carbene, and silylene donors resulting in stable adducts or bond activation of the ferrocenophane bridge. In the absence of donors, dimerization of the phosphenium cation to the corresponding dication is observed or P−C bond activation with migration of a substituent leading to a putative phosphoniodiphosphene. Using 1,3-di-tert-butylimidazol-2-silylene as the donor, further reaction of the initially formed chlorosilane leads to activation of a P−P bond of the ferrocenophane scaffold with ring expansion of the ansa-bridge. The donor formation and bonding situation are investigated by density functional theory calculations as well as experimental methods (e.g., NMR spectroscopy and X-ray crystallography).

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“… − For instance, compounds A , B , and C belong to these categories and thus react accordingly (Chart ). − However, although the difference between phosphides and phospheniums seems obvious, the electronic properties of substituents X can somewhat blur the distinction between these two classes of compounds . Thus, phosphide D and phosphenium E (which, respectively, contain electron-withdrawing and electron-donating substituents) both display ambiphilic character. − In extreme cases, net charges become all but insignificant: compound F can bind up to two metal centers, − which clearly makes it a competent Lewis base …”

Section: Introductionmentioning

confidence: 99%

Template Synthesis of NPN′ Pincer-type Ligands at Titanium Using an Ambiphilic Phosphide Scaffold

et al. 2022

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Ti-imido complex [TiCl(N t Bu)(BIPP)] [1; BIPP = bis(iminophosphoranyl)phosphide ligand] reacts with terminal alkynes R–CCH (R = phenyl, isopropenyl, cyclopropyl, and 2-pyridyl) via P–P bond cleavage of the BIPP ligand. The resulting complexes [TiCl(NPN′)(NPhPPh2)] (2a–d) contain a pincer-type NPN′ phosphide ligand that incorporates the terminal alkyne and the imido ligand from complex 1. Complexes 2a–d feature two chiral centers (Ti and P) with interdependent absolute configurations; thus, they are formed stereoselectively. Complex 2a (R = phenyl) undergoes chloride abstraction with [Et3SiHSiEt3][B(C6F5)4], yielding [Ti(NPN′)(NPhPPh2)][B(C6F5)4] (3). Complex 3 is a moderately active and stereoselective initiator for the ring-opening polymerization of rac-lactide. Complex 3 activates the CO bond of 4-iodobenzaldehyde to give complex 4 as a single diastereomer despite the presence of three chiral centers. Complex 3 undergoes transmetallation with SbCl3, yielding [Sb(NPN′)][B(C6F5)4] (5) and [TiCl3(NPhPPh2)] (6) selectively. The bonding situation in 3 and 5 was analyzed using Bader’s atoms in molecules and the electron localization function, showing that the nitrogen atoms of the NPN′ ligand are electronically similar, and that the metal–phosphide interaction is more polar in the case of titanium.

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Cationic Carbene Analogues: Donor‐Free Phosphenium and Arsenium Ions

Cited by 21 publications

References 49 publications

Unique Phosphorus-Based Avenues for the Tuning of Functional Materials

Unique Phosphorus-Based Avenues for the Tuning of Functional Materials

Gradual Donor Stabilization of a Transient Ferrocene Bridged Bisphosphanyl Phosphenium Cation

Template Synthesis of NPN′ Pincer-type Ligands at Titanium Using an Ambiphilic Phosphide Scaffold

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