ChemInform Abstract: NMR OBSERVATION OF PLATINUM PHENYL INTERMEDIATES IN THE REACTION OF BENZENE WITH PLATINUM CHLORIDES

Gol’dshleger, N. F.; Nekipelov, V. M.; Nikitaev, A. T.; Zamaraev, K. I.; Шилов, А. Е.; Shteinman, A. A.

doi:10.1002/chin.197931058

Cited by 79 publications

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“…[3][4][5][6] Almost all transformations of methane require high temperatures above 500°C, and only in recent years have new methods of C-H activation been reported for it. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] The partial oxidation of methane into valuable oxygenates (methanol, formaldehyde, formic acid) at temperatures below 100°C remains a challenging task for homogeneous catalysis.…”

Section: Introductionmentioning

confidence: 99%

Catalytic functionalization of methane

Süß‐Fink

Stanislas

Shul’pin

et al. 2000

Appl. Organometal. Chem.

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Section: Introductionmentioning

confidence: 99%

Catalytic functionalization of methane

Süß‐Fink

Stanislas

Shul’pin

et al. 2000

Appl. Organometal. Chem.

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“…It is worth to be pointed out that we have developed a suitable protocol for analyzing our concentrated sulfuric acid containing reaction liquids. Instead of those normally utilized deuterated solvents, we are using 98% D 2 SO 4 as the solvent and CH 3 COOH as the internal standard for most NMR measurements. A Varian Mercury 300 MHz NMR spectrometer was utilized to conduct all NMR measurements.…”

Section: Characterizations and Quantificationsmentioning

confidence: 99%

“…We have been able to efficiently screen out several types of extremely stable ionic liquids which can survive under the harsh conditions (high temperature, strong acid and oxidant, powerful catalyst) of catalytic methane conversion. 4 at atmospheric pressure using oil bath (200 ºC) and magnetic stirring. The rates were all normalized to reference ternary systems that were prepared at room temperature.…”

Section: Low Pressure Reactorsmentioning

confidence: 99%

“…An HP 6890 GC with MSD detector and specially designed sample holder was used for the quantification of the deuterated methane isotopomers produced from the H/D exchange experiments designed for investigating the C-H activation of methane. 4 (with 3% Ar as the internal standard). The short reactor was loaded with 1 mL reaction liquid and 500 psi CH 4 .…”

Section: Characterizations and Quantificationsmentioning

confidence: 99%

“…4 (with 3% Ar as the internal standard). The short reactor was loaded with 1 mL reaction liquid and 500 psi CH 4 . Both were heated at 150 °C for 2 hours.…”

Section: Characterizations and Quantificationsmentioning

confidence: 99%

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Using Ionic Liquids in Selective Hydrocarbon Conversion Processes

Tang¹,

Periana²,

Chen³

et al. 2009

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Vedernikov

Caulton

2002

Angew. Chem.

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The ability of platinum compounds to activate methane catalytically in aqueous solution was first described more than 30 years ago. [1] Determining the mechanism of the Shilov reaction, which was considered to be an oxidative addition of an alkane to a platinum(ii) center, remained challenging for over 25 years. First, increasingly persistent alkylhydridoplatinum(iv) complexes have been discovered, [2] and then the ability of platinum(ii) species to add hydrocarbons to produce very stable platinum(iv) alkyl hydrides was demonstrated. [3] Recent work [4] has shown that the transient [LPtCH 3 ] þ , where L is a ligand that cannot structurally accommodate the square-planar geometry preferred by four-coordinate Pt II species and only modestly stabilizes the related octahedral alkane oxidative addition products, cleaves alkane CÀH bonds. Here L is [2.1.1]-(2,6)-pyridinophane, and the transient is available according to Equation (1) in Scheme 1. This transient cleaves one substrate C À H bond, but methane is eliminated easily from the Pt IV intermediate 1; b-H elimination from the derived Pt II alkyl compound then leads to net conversion of alkane to (coordinated) olefin, thus accomplishing a second substrate CÀH bond cleavage.To obtain alkane activation products different from the hydrido olefin complexes, we suggest here a modification of the starting dialkylhydridoplatinum(iv) complex to allow only an alkane single CÀH bond activation event. For this we needed a species with a single alkyl ligand attached to a platinum(iv) center which will leave one hydride in the transient [LPtX] þ (X ¼ H) species. As a synthetic source of this transient, we initially considered whether [LPtMe(H) 2 ] þ would selectively eliminate methane rather than H 2 . The same question has been addressed recently for the complex TpPtMeH 2 . [5] The free energies for methane and for H 2 elimination from [LPtMe(H) 2 ] þ were calculated (DFT, PBE functional, [6] SBK basis set, [7] and program package Priroda [8] ; Figure 1) and show that methane elimination is favored, both thermodynamically and kinetically, [9] by more than 13 kcal mol À1 relative to H 2 elimination. Due to the macrocycle constraints, Pt II cannot achieve a planar four-coordinate geometry in [LPtH] þ (Figure 1), and the best geometry is three-coordinate T-shaped, with only 14 valence electrons. The out-of-plane pendant N3 atom interacts negligibly with the Pt II center, and the longer distance of Pt to N2 than to N1 shows the trans influence of hydride. [10] Based on the energies in Figure 1, we expected to develop reversible alkane single C À H bond activation chemistry with a [LPtH] þ transient; this is unprecedented for Pt II .The synthesis of [LPtMe(H) 2 ] þ , [11] as its [BAr F 4 ] À salt (Ar F ¼ 3,5-(CF 3 ) 2 C 6 H 3 ), is summarized in Equation (2) (> 98 % yield based on NMR data, relative to signal for BAr F 4 ; yield of isolated product 85 %). The new dihydridoplatinum(iv) complex is air-and water-stable and can be recrystallized from a warm water±methanol mixture. No...

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ChemInform Abstract: NMR OBSERVATION OF PLATINUM PHENYL INTERMEDIATES IN THE REACTION OF BENZENE WITH PLATINUM CHLORIDES

Cited by 79 publications

References 0 publications

Catalytic functionalization of methane

Catalytic functionalization of methane

Using Ionic Liquids in Selective Hydrocarbon Conversion Processes

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