Mesitylene complexes

Since the FeCp(C6H6)+ unit is robust towards oxidation even in concentrated sulfuric acid, oxidation of alkyl substituents upon boiling in aqueous KMn04 solution can be achieved and leads to carboxylic substituents. The mesitylene complex can be oxidized to the mono-, di-, or tri-carboxylic add depending upon the reaction conditions. In the latter case, the decomplexed trimesic acid is obtained [106, 107] Scheme XXII ... 

In a reaction that similarly relies on the acidity of benzylic protons in arene-ruthenium(II) complexes, the r 6-mesitylene complex 92 containing bidentate (C6F5)2PCH2CH2P(C6F5)2 loses two molecules of HF on treatment with proton sponge to give the di-strapped salt 93 in which each tether contains three carbon atoms [Eq. (18)]).83... 

Compound Ru3(CO)i2 reacts with arenes under reflux, yielding complexes RugC(CO)i4(arene) (arene = toluene, m-xylene, mesitylene) 241, 242). The structure of the mesitylene complex (XXIV) has been determined by X-ray analysis 285). 

The corresponding j -mesitylene complex Vir reacts exclusively at an unsubstituted arene position to give VIII ... 

With alkyl substituents on the arene ligand, proton abstraction from the benzylic carbon can compete with nucleophilic addition, especially with hard nucleophiles such as amide and alkoxide anions . The result of benzylic proton abstraction is the formation, in low yield, of dimer XIV from nucleophilic addition of the benzyl carbon to another jj -mesitylene complex ... 

The magnitude of the heat of solution of GaCls in benzene has been used to estimate the heat of formation of the complex GaClj CgH as 11.3 kcal mol . The value for the analogous mesitylene complex is 15.2 kcal mol. ... 

Other complex structures which show similar packing arrangements based on charge-transfer interactions include the 1 1 complexes of mesitylene-hexafluorobenzene, thymine-p-benzoquinone, and the 1 2 complex formed by phlorogludnol and p-benzoquinone. The mesitylene complex consists of alternately stacked molecules of mesitylene and hexa-fluorobenzene [separation 3.56 A]. There are also nearly linear C-H F [3.24 A] intermolecular contacts, and the possibility of methyl-fluorine hydrogen-bonding cannot be discounted. The structures of both the thymine and phlorogludnol complexes with p-benzoquinone may be described In... 

Both dimesitylchromium(II) 166) and trimesitylchromium(III) (167) (isolated as tctrahydrofuranates) undergo simple hydrolysis to mesitylene and chromium salts without formation of the 77-mesitylene complex. Pyrolysis of the a-mesityl compounds leads to complete decomposition. Electron-withdrawing substituents (e.g., halogen) that destabilize the TT-complexes also prevent the tr-aryl to tr-arene conversion (168). 

At constant temperature on the SE-30 column, the separation of para- and meta-xylenetricarbonylchromiums is poor the complexes of orthoxylene and ethylbenzene are eluted in the same time and are not completely resolved from the mesitylene complex. The selectivity of the Apiezon L column is greater for the xylene derivatives and the separation of o-xylene and ethylbenzene complexes is improved but the resolution of mesitylene- and pseudocumeme-tricarbonyl-chromiums is bad. Figure 215 shows a chromatogram of a benzene solution of the thirteen derivatives, obtained at 140°C with a SE-30 column. 

Indeed, with CgMes, only one H out of three is usually replaced by the electrophilic group (with the reactive allyl bromide, a slow second substitution can be slowly achieved), whereas two H atoms out of three are replaced by the electrophile in each methyl group in the o-xylene and durene complexes, and all the three H atoms are replaced by electrophiles in the tolene, p-xylene and mesitylene complexes. 

An unusual AgaO-mediated isomerization of mesitylene complex 266, containing a dianionic chelating ligand derived from 2-acetamidocinnamic acid, has been reported to yield the cyclometallated alkenyl derivative 267 (Equation (18)). Other alkenyl-cyclometallated derivatives 285 are also known (see Section 6.15.3.3). 

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