Transition‐Metal‐Free Boron–Carbon Bond Activation: Insertion of an NNP Fragment into a Boron–Carbon Bond

Kowalewski, Markus; Krumm, Burkhard; Mayer, Péter; Schulz, Axel; Villinger, Alexander

doi:10.1002/ejic.200700895

Cited by 12 publications

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“…This reaction only occurs when a Lewis acid is added, as it induces Me 3 SiCl elimination and thus the release of the reactive iminopnictane. [7,8] Substitution of two nitrogen atoms in pentazoles by heavier Group 15 elements leads to triazadipnictoles, RN 3 E 2 , of which only the triazadiphosphole [4b, 9,10] was reported (E = P, R = N(SiMe 3 ) 2 , Mes*). All other classes of heterocycles consisting only of Group 15 atoms, namely RN 2 E 3 , RNE 4 , and RE 5 , remain unknown.…”

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confidence: 99%

“…To the best of our knowledge, analogous Group 15 heterocycles involving Sb and Bi have not been reported. Following our interest in Group 15 element nitrogen compounds with a high nitrogen content, [4][5][6][7][8][9][10][11] we describe herein the synthesis, isolation, and full characterization of a tetraazastibole, RN 4 Sb (R = Mes*), stabilized as B(C 6 F 5 ) 3 adduct.…”

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confidence: 99%

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An Unusual Isomerization to Tetraazastiboles

2011

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Dedicated to Professor Peter Klüfers on the occasion of his 60th birthdayPentazoles are aromatic molecules consisting of a fivemembered nitrogen-atom ring (Scheme 1), one of which is bonded to a hydrogen atom (HN 5 ) or an organic substituent (RN 5 ; R is usually an aryl group). They form a class of highly endothermic and explosive compounds. The existence of an all-nitrogen aromatic azole ring, RN 5 (R = C 6 H 5 ), was considered by Clusius and Hurzeler [1] and shown by Huisgen and Ugi [2] in the reaction of phenyldiazonium chloride, [C 6 Substitution of one nitrogen atom in pentazoles by a heavier element of Group 15 leads to isovalent tetraazapnictoles (Scheme 1), RN 4 E (E = P, As, Sb, Bi), which also have electronic structures that are related to those of aromatic hydrocarbons with (4n + 2)p electrons.[3] Only recently, two examples of tetraazapnictoles (E = P, R = Mes* = 2,4,6-tritert-butylphenyl or m-Ter = 2,6-bis(2,4,6-trimethylphenyl)-phenyl;[4a, 5] E = As, [6] R = Mes*) have been isolated and fully characterized. Two different synthetic routes to tetraazapnictoles have been described: [4,6]

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An Unusual Isomerization to Tetraazastiboles

2011

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“…B–C activation processes of this type are known for transition‐metal complexes, such as zirconocene species, shown by the groups of Rosenthal and Bochmann,51–53 and in reactions of B(C 6 F 5 ) 3 with alkynes, demonstrated by Stephan54 and Erker 55. Our group proved that in situ generated, highly labile (Me 3 Si) 2 NNP + can activate one BC bond in B(C 6 F 5 ) 3 56. Colorless crystals of 10 melted at 71 °C and decomposed at 102 °C.…”

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confidence: 57%

“…[55] Our group proved that in situ generated, highly labile (Me 3 Si) 2 NÀNP + can activate one BÀC bond in B(C 6 F 5 ) 3 . [56] Colorless crystals of 10 melted at 71 8C and decomposed at 102 8C. The 11 B NMR resonance was found at d = 40.2 ppm (see Table 1).…”

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Synthesis, Structure, and Reactivity of Diazene Adducts: Isolation of iso‐Diazene Stabilized as a Borane Adduct

Reiß

Schulz

Villinger

2014

Chemistry A European J

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This work describes the synthesis and full characterization of a series of GaCl3 and B(C6 F5 )3 adducts of diazenes R(1) NNR(2) (R(1) =R(2) =Me3 Si, Ph; R(1) =Me3 Si, R(2) =Ph). Trans-PhNNPh forms a stable adduct with GaCl3 , whereas no adduct, but instead a frustrated Lewis acid-base pair is formed with B(C6 F5 )3 . The cis-PhNNPh⋅B(C6 F5 )3 adduct could only be isolated when UV light was used, which triggers the isomerization from trans- to cis-PhNNPh, which provides more space for the bulky borane. Treatment of trans-PhNNSiMe3 with GaCl3 led to the expected trans-PhNNSiMe3 ⋅GaCl3 adduct but the reaction with B(C6 F5 )3 triggered a 1,2-Me3 Si shift, which resulted in the formation of a highly labile iso-diazene, Me3 Si(Ph)NN; stabilized as a B(C6 F5 )3 adduct. Trans-Me3 SiNNSiMe3 forms a labile cis-Me3 SiNNSiMe3 ⋅B(C6 F5 )3 adduct, which isomerizes to give the transient iso-diazene species (Me3 Si)2 NN⋅B(C6 F5 )3 upon heating. Both iso-diazene species insert easily into one BC bond of B(C6 F5 )3 to afford hydrazinoboranes. All new compounds were fully characterized by means of X-ray crystallography, vibrational spectroscopy, CHN analysis, and NMR spectroscopy. All compounds were further investigated by DFT and the bonding situation was assessed by natural bond orbital (NBO) analysis.

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“…Entsprechend unseres Interesses an stickstoffreichen Verbindungen mit Elementen der 15. Gruppe, [4][5][6][7][8][9][10][11] beschreiben wir hier erstmalig die Synthese, Isolierung und vollständige Charakterisierung eines Tetraazastibols, RN 4 Sb (R = Mes*), stabilisiert als B(C 6 F 5 ) 3 -Addukt.…”

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Eine ungewöhnliche Isomerisierung zu Tetraazastibolen

2011

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Professor Peter Klüfers zum 60. Geburtstag gewidmet Pentazole sind aromatische Moleküle mit einem fünfgliedri-gen Stickstoffring (Schema 1), in dem ein N-Atom mit einem Wasserstoffatom, HN 5 , oder einem organischen Rest, RN 5 , verknüpft ist (wobei R meistens ein aromatischer Rest ist).Sie bilden eine Klasse hoch explosiver und endothermer Verbindungen. Die Existenz eines aromatischen Stickstoffrings in RN 5 (R = C 6 H 5 ) wurde zuerst von Clusius und Hurzeler [1] in Betracht gezogen und schließlich von Huisgen und Ugi [2] in der Reaktion von Phenyldiazoniumchlorid, [C 6 Tetraazapniktolen (Schema 1), RN 4 E (E = P, As, Sb und Bi), die über (4n + 2) p-Elektronen verfügen und in dieser Hinsicht mit aromatischen Kohlenwasserstoffen vergleichbar sind.[3] Erst kürzlich konnten zwei Tetraazapniktole (E = P, R = Mes* (2,4,6-Tri-tert-butylphenyl) oder m-Ter (2,6-Bis(2,4,6-trimethylphenyl)phenyl); [4a, 5] E = As,[6] R = Mes*) isoliert und vollständig charakterisiert werden. Zwei verschiedene Synthesewege für Tetraazapniktole sind bekannt: [4,6] [7,8] Durch Substitution von zwei Stickstoffatomen in Pentazolen durch schwerere Elemente der 15. Gruppe gelangt man zu Triazadipniktolen RN 3 E 2 von denen nur die Triazadiphosphole [4b, 9, 10] bekannt sind (E = P, R = N(SiMe 3 ) 2 , Mes*). Alle anderen Klassen, in denen der Heterocyclus nur aus Elementen der 15. Gruppe aufgebaut ist, -RN 2 E 3 , RNE 4 und RE 5 -sind unbekannt. Unseres Wissens gibt es keine analogen Heterocyclen der 15. Gruppe, in denen Sb-oder BiAtome enthalten sind. Entsprechend unseres Interesses an stickstoffreichen Verbindungen mit Elementen der 15. Gruppe, [4][5][6][7][8][9][10][11] beschreiben wir hier erstmalig die Synthese, Isolierung und vollständige Charakterisierung eines Tetraazastibols, RN 4 Sb (R = Mes*), stabilisiert als B(C 6 F 5 ) 3 -Addukt.Um das Tetraazastibol Mes*N 4 Sb zu synthetisieren, wurden beide in Schema 2 vorgestellten Synthesewege beschritten (Methode A und B). Zuerst wurde das Gleichge-

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Transition‐Metal‐Free Boron–Carbon Bond Activation: Insertion of an NNP Fragment into a Boron–Carbon Bond

Cited by 12 publications

References 18 publications

An Unusual Isomerization to Tetraazastiboles

An Unusual Isomerization to Tetraazastiboles

Synthesis, Structure, and Reactivity of Diazene Adducts: Isolation of iso‐Diazene Stabilized as a Borane Adduct

Eine ungewöhnliche Isomerisierung zu Tetraazastibolen

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