Isolation of a Labile Homoleptic Diazenium Cation

Baumann, Wolfgang; Michalik, Dirk; Reiß, Fabian; Schulz, Axel; Villinger, Alexander

doi:10.1002/anie.201310186

Cited by 20 publications

(28 citation statements)

References 42 publications

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“…and only C 1 symmetry, presumably due to intramolecular dispersion interactions (Figure ). A similar distortion was also observed in the closely related compound Hg[N(SiMe 3 )N(SiMe 3 ) 2 ] 2 …”

Section: Resultssupporting

confidence: 73%

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂

et al. 2018

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The solid‐state structure and Raman spectrum of Wannagat's mercurane, Hg[N(SiMe3)2]2 (1), are reported. Crystals were grown from the pure substance by slow cooling to –24 °C. Compound 1 crystallizes in the monoclinic space group P21/c as discrete monomers, which do not display intermolecular mercurophilic interactions. The molecular structure features a nearly linear N–Hg–N scaffold, while the (Me3Si)2N groups are in a staggered conformation with a dihedral angle of 58.3° (average) to each other. This can be attributed to intramolecular dispersion interactions according to DFT calculations.

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Section: Resultssupporting

confidence: 73%

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂

et al. 2018

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“…Compound 5 (Figure 3 top) crystallizes in the monoclinic space group P 2 1 / c with eight formula units per cell. For the two independent molecules the same positional disorder was observed as discussed for trans ‐PhNNPh95 and 2 37. The observed molecular structure exhibits the expected trans configuration (Si‐ N ‐N‐C=179.7°) with a short N–N distance (1.238(2) Å; cf.…”

Section: Resultssupporting

confidence: 70%

“…The starting point of this project was the attempted direct silylation of diazenes R 1 NNR 2 (R 1 =R 2 =SiMe 3 ,37 Ph; R 1 =Me 3 Si, R 2 =Ph) with trimethylsilicenium‐solvate tetrakis(pentafluorophenyl)borate salts of the type [Me 3 Si ⋅ X][B(C 6 F 5 ) 4 ] (X=toluene, Me 3 SiH), all of which failed to generate diazenium cations of the type [R 1 NN(SiMe 3 )R 2 ] + or [R 1 (Me 3 Si)NNR 2 ] + . Only decomposition or mixtures of products were observed, even at low temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…The reaction of tosylazide with lithium tris(trimethylsilyl)hydrazide ( 1 ) at low temperatures provides ready access to light‐blue trans ‐diazene Me 3 SiNN‐SiMe 3 ( 2 ) in approximately 65 % yield (Scheme ) 23. Because 2 decomposes at ambient temperatures with a half‐life of 7.6 h it must be stored at temperatures below −50 °C 37. As shown by Wiberg, a higher degree of silylation in diazenes caused an increase of the HOMO ( n N ) and decrease of the LUMO (π* NN ) energies 38.…”

Section: Introductionmentioning

confidence: 99%

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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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“…The dicationic species formed upon two‐electron oxidation could be described as special diimines (or diazenes). While diimines with aryl substituents were studied intensively, much less is known about diimines with other substituents 31. The aryl substituents stabilize the compounds through π‐bonding, and such a stabilization is also active in the case of the dications 2 2+ – 4 2+ .…”

Section: Resultsmentioning

confidence: 99%

Urea Azines (Bisguanidines): Electronic Structure, Redox Properties, and Coordination Chemistry

et al. 2015

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Urea azines are a largely neglected class of compounds. We show herein that they can easily be synthesized and sublimed at higher temperatures (90–100 °C) without decomposition. Our discussion includes the derivatives N,N′‐diisopropylurea azine (2), tetramethylurea azine (3), and N,N′‐dimethylethyleneurea azine (4) as examples. Vibrational spectroscopy and quantum chemical calculations were used to study their electronic structure in detail. A clear trend in the calculated decomposition to N2 and carbene is found, but the analysis reveals that this trend reflects the stability of the carbene decomposition product rather than changes in the electronic structure of the urea azines. Using cyclic voltammetry (CV) measurements we show that the urea azines are strong organic electron donors, which can be oxidized reversibly in two well‐separated one‐electron steps. The radical salt 4(TCNQ), featuring radical monocations and radical monoanions, which form mixed stacks in the solid state, was prepared by reaction of neutral 4 with tetracyanoquinodimethane (TCNQ). Oxidation of 4 with silver salts Ag+X– (X = BF4 or PF6) was accompanied by dehydrogenation, leading to intensively red‐brown colored radical azoimidazolium dyes. Furthermore, urea azines were used as chelating ligands. In the case of 2, coordination to late transition metals initiates tautomerization. Reaction of 2 with boron hydrides leads to hydrogen elimination and formation of new B,N bi‐heterocyclic ring structures.

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Isolation of a Labile Homoleptic Diazenium Cation

Cited by 20 publications

References 42 publications

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂

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

Urea Azines (Bisguanidines): Electronic Structure, Redox Properties, and Coordination Chemistry

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Isolation of a Labile Homoleptic Diazenium Cation

Cited by 20 publications

References 42 publications

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe3)2]2

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe3)2]2

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

Urea Azines (Bisguanidines): Electronic Structure, Redox Properties, and Coordination Chemistry

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Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂

Dispersion Makes a Difference – The Solid‐State Structure of Hg[N(SiMe₃)₂]₂