Different outcomes in the reactions of WCl6 with carboxylic acids

Abstract

The reactions of WCl6 with a selection of carboxylic acids were investigated by using dichloromethane as reaction medium. The addition of pyridine-3-carboxylic acid (niacin) to WCl6 gave [C5H4NHC(O)Cl][WOCl5], 1, in 75% yield via selective Cl/O interchange. WCl6 reacted with RCO2H (R = CH3, CBr3, CHCl2) in 1:2 ratio resulting in the formation of HCl and the respective acyl chlorides, RC(O)Cl. WOCl4(κ1-CH3CO2H), 2, was isolated from WCl6/CH3CO2H in 41% yield. The 1:2 reaction of WCl6 with CCl3CO2H proceeded with HCl release affording a mixture of WCl5(O2CCCl3), 3, and WCl4(O2CCCl3)2, 4. Compound 3 was isolated from WCl6/CCl3CO2H (1:1 ratio) in 60% yield. All the metal products were characterized by analytical and spectroscopic techniques. The crystal structure of 1 was ascertained by X-ray diffractometry. DFT calculations were carried out in order to shed light into structural, mechanistic and thermodynamic features

Cascade Reactions of α‐Phenylcinnamic Acid to Polycyclic Compounds Promoted by High Valent Transition Metal Halides

“…Considering the powerful chlorinating ability of WCl 6 ,, we reckoned that the direct reaction of cis ‐PhCH=CPhC(=O)OH with WCl 6 could efficiently reproduce the formation of 1 , via initial, in situ Cl/O transfer between the metal and the organic substrate. The use of WCl 6 appeared convenient also in that one equivalent of WCl 6 , in principle, could serve the chlorination of two equivalents of acid, the former converting into WO 2 Cl 2 .…”

“…Therefore, NbF 5 forms coordination adducts upon interaction with carboxylic acids, while NbCl 5 manifests the typical reactivity of low to middle valent transition metal chlorides, affording metal carboxylates through HCl release . Conversely, the chemistry of WCl 6 (and the related group 6 chloride MoCl 5 ) with simple carboxylic acids (RCO 2 H) somehow resembles that of PCl 5 , and Cl/O exchange is usually working to give the corresponding acyl chlorides RC(O)Cl, possibly accompanied by side reactions . In this setting, the interaction of high valent metal halides with carboxylic acids (and their acyl chloride counterparts) with an additional, adjacent function has been sparingly explored heretofore.…”

“…[17] Conversely, the chemistry of WCl 6 (and the related group 6 chloride MoCl 5 ) with simple carboxylic acids (RCO 2 H) somehow resembles that of PCl 5 , [18] and Cl/O exchange is usually working to give the corresponding acyl chlorides RC(O)Cl, possibly accompanied by side reactions. [19] In this setting, the interaction of high valent metal halides with carboxylic acids (and their acyl chloride counterparts) with an additional, adjacent function has been sparingly explored heretofore.…”

Metallic Tungsten Nanoparticles That Exhibit an Electronic State Like Carbides during the Carbothermal Reduction of WCl6 by Hydrogen

“…Tungsten hexachloride (WCl 6 ) has been used as a starting material to produce metal complexes, − macromolecular complexes, clusters, and nanoparticles . As WCl 6 is a reactive and labile compound, it is very prone to the formation of oxides via hydrolysis. , However, when used as a precursor for CHR, WCl 6 can, rather than undergoing hydrolysis, be easily reduced by hydrogen to metallic tungsten because it has a lower standard Gibbs energy of reaction (Δ r G °) compared to WO 3 : Therefore, the WCl 6 precursor should produce metallic W nanoparticles on a carbon support at moderate temperatures during the CHR process.…”

Reactivity of [WCl6] with Ethers: A Joint Computational, Spectroscopic and Crystallographic Study

“…Mono‐electron transfer from the organic substrate to [WCl 6 ] has been recognized in the reactions with some tetraalkylureas, leading to unusual C–H bond activation . On the other hand, [WCl 6 ] has been proposed as a Cl/O interchange agent in reactions with the carbonyl moiety of aldehydes/ketones,[3b] amides,[3b], esters, α‐amino acids[10a] and carboxylic acids . Both oxygen abstraction from the metal centre and electron‐interchange pathways may be operating when [WCl 6 ] is allowed to contact with esters[3b], and amides.…”