Using Ylide Functionalization to Stabilize Boron Cations

Scherpf, Thorsten; Feichtner, Kai‐Stephan; Gessner, Viktoria H.

doi:10.1002/ange.201611677

Cited by 15 publications

(3 citation statements)

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“…This was confirmed by the short C–B distances as well as the π bonding obvious in the molecular orbitals of 20 . Furthermore, the high donor strength of the ylide ligand was demonstrated by the stabilization of boron cations . These were found to be readily available by hydride abstraction from 20 using trityl salts with weakly coordinated anions or the highly Lewis acidic B(C 6 F 5 ) 3 .…”

Section: Reactivity and Coordination Ability Of Metalated Ylidesmentioning

confidence: 99%

“…Furthermore, the high donor strength of the ylide ligand was demonstrated by the stabilization of boron cations. 30 These were found to be readily available by hydride abstraction from 20 using trityl salts with weakly coordinated anions 31 or the highly Lewis acidic B(C 6 F 5 ) 3 . 32 Cation 21 and Lewis base adducts thereof were revealed to be thermally highly stable.…”

Section: Reactivity and Coordination Ability Of Metalated Ylidesmentioning

confidence: 99%

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Metalated Ylides: A New Class of Strong Donor Ligands with Unique Electronic Properties

Scharf

Gessner

2017

Inorg. Chem.

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The development and design of new ligand systems with special donor properties has been essential for crucial advances made in main-group-element and transition-metal chemistry over the years. This Forum Article focuses on metalated ylides as novel ligand systems. These anionic congeners of bisylides possess likewise two lone pairs of electrons at the central carbon atom and can thus function as X,L-type ligands with strong donor abilities. This article highlights recent efforts in the isolation and application of metalated ylides with a focus on work from this laboratory. We summarize structural and electronic properties and their use in organic synthesis as well as main-group-element and transition-metal chemistry.

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Section: Reactivity and Coordination Ability Of Metalated Ylidesmentioning

confidence: 99%

Section: Reactivity and Coordination Ability Of Metalated Ylidesmentioning

confidence: 99%

Metalated Ylides: A New Class of Strong Donor Ligands with Unique Electronic Properties

Scharf

Gessner

2017

Inorg. Chem.

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“…[48] Gessner and co-workers described the boron complex salt 29[PF 6 ]t hat bears two anionic carbon ylidic ligands and which was isolated and characterizedb yX RD analysis( Figure 9). [49] This ligand is marked by af ormally anionic carbon center with two lone pairs and, hence, it resembles an egatively charged version of the non-ionic carbone-typel igand mentioned above.The complex (29 + )w as accessed by hydride abstraction from the bisylide borane (Y 2 BH, Y = anionic ylide) using different salts of trityl cation with aW CA or using B(C 6 F 5 29[HB(C 6 F 5 ) 3 ]) formed highly viscous oils. Therefore, salt metathesis by means of Bu 4 N[PF 6 ]w as employed to craft ac omplex salt which was isolated in analytically pure form.…”

Section: Three-coordinate Boron(iii) Complexes With One Cationic Charmentioning

confidence: 97%

Cationic Complexes of Boron and Aluminum: An Early 21st Century Viewpoint

Franz

Inoue

2018

Chemistry A European J

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Boron and aluminum share one main group, they are found in daily life commodities, and considered environmentally benign. Nevertheless, they markedly differ in their element properties (e.g. metal character, atomic radius). The use of Lewis acidic complexes of boron and aluminum for methods of bond activation and catalysis (e.g. hydrogenation of unsaturated substrates, polymerization of olefins and epoxides) is quickly expanding. The introduction of cationic charge may boost the metalloid-centered Lewis acidity and allows for its fine-tuning particularly with regard to preference for "hard" or "soft" Lewis bases (i.e. substrates). Especially, the isolation of low-coordinate cations (number of ligand atoms smaller than 4) demands for elaborate techniques of thermodynamic and kinetic stabilization (i.e. electronic saturation and steric shielding) by a ligand system. Furthermore, the properties of the solvent and the counteranion have to be considered with care. Herein, we revise selected examples for boron and aluminum cations.

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Formation of an Isolable Divinylborinium Ion through Twofold 1,2‐Carboboration between a Diarylborinium Ion and Diphenylacetylene

et al. 2017

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Borinium ions,that is,two-coordinate boron cations, are the most electron-deficient isolable boron compounds.A s borinium ions have only four formal valence electrons on boron, they should show as trong tendency to accept electron pairs on the boron atom to fill its valence shell. Thus chemical reactions of borinium ions are expected to give products in which the coordination number of boron is increased from two to three or four.H owever,c ontrary to this expectation, we found that the dimesitylborinium ion (Mes 2 B + )u ndergoes twofold 1,2-carboboration reactions with two equivalents of diphenylacetylene to yield an unprecedented borinium ion (1 + ) with two substituted vinyl groups on the boron center.N MR spectroscopya nd X-rayd iffraction analysis of 1 + ,t ogether with electronic-structure calculations,revealed that the positive charge is delocalized over the entire p-conjugated system. The fact that the chemical transformation of ab orinium ion gives rise to ad ifferent borinium ion without ac hangei nt he coordination number is remarkable and should provide new insight into the chemistry of the Group 13 elements.Boron cations have attracted considerable attention from the viewpoint of the chemistry of Group 13 elements as well as chemical bonding theory. [1] Boron cations are classified into four-coordinate boronium [R 2 B + (DL) 2 ], three-coordinate borenium [R 2 B + (DL)],a nd two-coordinate borinium [R 2 B + ] ions (Figure 1). [1a,b] Among these,borinium ions are the most electron-deficient species as they have only four formal valence electrons on the boron center, and thus significantly deviate from the octet rule.U ntil recently,t he chemical reactivity of borinium ions had remained elusive. [1] In 2014, we reported the first successful isolation of the dimesitylborinium ion (Mes 2 B + ) [2] using chemically stable and weakly nucleophilic counteranions,s uch as the carborane anion [HCB 11 Cl 11 ] À [3] and the tetraarylborate [(C 6 F 5 ) 4 B] À [4] (Figure 2). We found that Mes 2 B + shows exceptional Lewis acidity and chalcogenophilicity to cause carbon-chalcogen double bond cleavage reactions of CO 2 and CS 2 at room temperature. [2a,b] These reactions were initiated by the addition of the chalcogen atom of CO 2 or CS 2 to the cationic boron center of Mes 2 B + .As indicated by these examples,highly electron-deficient borinium ions should have as trong tendencyt oa ccept electron pairs to fill the valence shell of the boron atom, giving rise to products with an increased coordination number for the boron center. However,wediscovered an unexpected Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.doi.org/10.1002/anie.201701730.Figure 1. Schematic representations of boron cations. LD = Lewis base.Figure 2. Transformation of the diarylborinium ion Mes 2 B + into the divinylborinium ion 1 + through twofold 1,2-carboboration with diphenylacetylene. The use of carborane [HCB 11 Cl 11 ] À or tetraarylborate [(C 6 F 5 ) 4 B...

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Using Ylide Functionalization to Stabilize Boron Cations

Abstract: LB by addition of Lewis bases such as amines and amides.P rimary and secondary amines react to tris-(amino)boranes via N À Ha ctivation across the B À Cbond.

Cited by 15 publications

References 74 publications

Metalated Ylides: A New Class of Strong Donor Ligands with Unique Electronic Properties

Metalated Ylides: A New Class of Strong Donor Ligands with Unique Electronic Properties

Cationic Complexes of Boron and Aluminum: An Early 21st Century Viewpoint

Formation of an Isolable Divinylborinium Ion through Twofold 1,2‐Carboboration between a Diarylborinium Ion and Diphenylacetylene

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