The 1,1,2,3,4,5,6-heptamethylbenzenonium ion

Doering, W. von E.; Saunders, Martin; Boyton, H.G.; Earhart, H.W.; Wadley, E.F.; Edwards, W.R.; Laber, G.

doi:10.1016/0040-4020(58)88016-3

Cited by 112 publications

(11 citation statements)

References 24 publications

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“…The 13 C Dd patterns point to the C b site on the flanking arene as the dominant site of the interaction, but do not resolve whether all four C b sites interact simultaneously through the C 2v conformation or each C b site contributes through an equilibrium of lower symmetry geometries with the silicon-arene interactions. The C 2v and C s conformers seem geometrically unreasonable, as silicon would have to interact with two C b atoms of the same ring without interacting with C a atoms.…”

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confidence: 93%

“…Wheland complexes display an upfield shift of the 13 C signal of the tetracoordinate atom relative to those of free arenes, whereas the other carbon atoms are more deshielded. [13] For the heptamethylbenzenium ion, for example, large signal shifts of 57 ppm (C ipso ), 198 ppm (C ortho ), 139 ppm (C meta ), and 191 ppm (C para ) are observed (hexamethylbenzene has a shift of d = 133 ppm). [14] Complex formation between Et 3 Si + and toluene produces a similar but far less pronounced effect on the NMR shifts of the aryl carbon atoms.…”

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confidence: 99%

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Synthesis of 2,6‐Diarylphenyldimethylsilyl Cations: Polar‐π Distribution of Cation Character

Duttwyler

Linden

et al. 2008

Angew Chem Int Ed

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confidence: 93%

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confidence: 99%

Synthesis of 2,6‐Diarylphenyldimethylsilyl Cations: Polar‐π Distribution of Cation Character

Duttwyler

Linden

et al. 2008

Angew Chem Int Ed

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“…We proposed to use the 6-methylenecyclohexadiene-1,4 derivative C 6 Me 6 CH 2 (named hereafter as triene 2 ) as a source of the heptamethylcyclohexadienyl ligand (Scheme ). Triene 2 was obtained by a modified literature procedure from commercially available and inexpensive reagents: namely, mesitylene and chloromethane. First, mesitylene was exhaustively methylated by chloromethane in the presence of AlCl 3 to give the carbocationic salt [C 6 Me 7 ] + [AlCl 4 ] − ( 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…In the first step of the synthesis, some amounts of unreacted polymethylbenzenes remained; therefore, it was important to wash the salt 1 several times with toluene and diethyl ether before converting it into the triene 2 . This procedure allowed us to simplify the synthesis of 2 in comparison to the previously reported methods, in which it was purified by conversion to a hydrochloride and subsequent deprotonation. The structure of the triene 2 was established by X-ray diffraction (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Reactivity of Heptamethylcyclohexadienyl Rhodium(III) Complexes

2019

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We report the synthesis and reactivity of the halfsandwich rhodium(III) complexes with the fully methylated cyclohexadienyl ligand C 6 Me 7 , which is analogous to the classical Cp*. The starting complex [(C 6 Me 7 )RhCl 2 ] 2 (4) was obtained in high yield (92%) by the reaction of [(cyclooctene) 2 RhCl] 2 with the readily available 6-methylenehexamethylcyclohexadiene-1,4 (C 6 Me 6 CH 2 ) followed by addition of HCl. Reactions of complex 4 with common two-electron ligands L gave the expected adducts (C 6 Me 7 )RhCl 2 L (L = pyridine, P(OEt) 3 , PPh 3 ) in high yields (80−90%). At the same time, the interaction of 4 with the stronger ligand t BuNC led to the replacement of the C 6 Me 7 ligand. The cationic complex [(C 6 Me 7 )Rh(dppe)Cl]PF 6 and the dicationic complex [(C 6 Me 7 )Rh(C 6 Me 6 )](BF 4 ) 2 were obtained by abstraction of chlorides from 4 with TlPF 6 or AgBF 4 in the presence of the corresponding ligands. The reaction of 4 with 2-phenylpyridine in the presence of CsOAc proceeded via CH activation and gave the cyclometalated product (C 6 Me 7 )Rh(C 6 H 4 -Py)Cl in 85% yield. Accordingly, the catalytic reaction of 2phenylpyridine with 3-hexyne in the presence of 4 (5 mol %) gave the 9,10-diethyl-8a-azaphenanthrene cation in 61% yield. However, the catalytic efficientcy of 4 was lower than that of the classical catalyst [Cp*RhCl 2 ] 2 , possibly because the displacement of the cyclohexadienyl ligand interrupted the catalytic cycle. The DFT calculations suggested that the electrondonating ability of cyclic π ligands in the rhodium complexes (C n R n )RhCl 2 CO decreases in the order C

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“…It has been reported that aromatic HCs could react with the derivatization reagent to form benzenonium ions . Doering et al have proven that the terminal product from the Friedel–Craft methylation of toluene and its methyl homologues was 1,1,2,3,4,5,6-heptamethylbenzenonium, which was a comparatively stable carbonium ion. Therefore, we speculate that [C 13 H 21 ] + might be the terminal methylation product of toluene and its methyl homologues and [C 11 H 17 ] + and [C 12 H 19 ] + might be the intermediate state of [C 13 H 21 ] + .…”

Section: Resultsmentioning

confidence: 99%

Identification of Artifacts in the Methylation Process of Sulfur Compounds in Petroleum

et al. 2018

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Methylation of sulfides and thiophenes into methyl sulfonium salts for electrospray ionization (ESI) mass spectrometry analysis has been a widely used approach for molecular characterization of sulfur-containing compounds in fossil fuels. In this study, we found a series of artifacts in the methylation products of crude oils, which could lead to incorrect assignment of sulfur compounds, severe ionization suppression of S1 species with a high double bond equivalent value, and O x S x species with low abundance. The terminal products from the Friedel–Craft methylation of toluene and its methyl homologues were identified as 1,1,2,3,4,5,6-heptamethylbenzenonium, which showed high abundance in the positive-ion ESI mass spectrum. These compounds associate with Ag+, leading to the formation of abundant Ag-cationized monomer and homo- and hetero-Ag-cationized dimer complexes. In-source high-energy collisional dissociation (HCD) of the homo- and hetero-Ag-cationized dimer complexes [M1 + Ag + M1]+ and [M1 + Ag + M2]+ yielded the monomer complexes [M1 + Ag]+, which further fragmented to yield the molecular ion [M1]+. The abundant Ag-cationized complexes seriously interfered with the identification of sulfur compounds. Feasible suggestions are made to eliminate the interference by Ag-cationized complexes.

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The 1,1,2,3,4,5,6-heptamethylbenzenonium ion

Cited by 112 publications

References 24 publications

Synthesis of 2,6‐Diarylphenyldimethylsilyl Cations: Polar‐π Distribution of Cation Character

Synthesis of 2,6‐Diarylphenyldimethylsilyl Cations: Polar‐π Distribution of Cation Character

Synthesis and Reactivity of Heptamethylcyclohexadienyl Rhodium(III) Complexes

Identification of Artifacts in the Methylation Process of Sulfur Compounds in Petroleum

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