A detailed mechanistic study of arene C [bond] H activation in CH(2)Cl(2) solution by Cp(L)IrMe(X) [L = PMe(3), P(OMe)(3); X = OTf, (CH(2)Cl(2))BAr(f); (BAr(f) = B[3,5-C(6)H(3)(CF(3))(2)](4))(-)] is presented. It was determined that triflate dissociation in Cp(L)IrMe(OTf), to generate tight and/or solvent-separated ion pairs containing a cationic iridium complex, precedes C [bond] H activation. Consistent with the ion-pair hypothesis, the rate of arene activation by Cp(L)IrMe(OTf) is unaffected by added external triflate salts, but the rate is strongly dependent upon the medium. Thus the reactivity of Cp(PMe(3))IrMe(OTf) can be increased by almost 3 orders of magnitude by addition of (n-Hex)(4)NBAr(f), presumably because the added BAr(f) anion exchanges with the OTf anion in the initially formed ion pair, transiently forming a cation/borate ion pair in solution (special salt effect). In contrast, addition of (n-Hex)(4)NBAr(f) to [CpPMe(3)Ir(Me)CH(2)Cl(2)][BAr(f)] does not affect the rate of benzene activation; here there is no initial covalent/ionic pre-equilibrium that can be perturbed with added (n-Hex)(4)NBAr(f). An analysis of the reaction between Cp(PMe(3))IrMe(OTf) and various substituted arenes demonstrated that electron-donating substituents on the arene increase the rate of the C [bond] H activation reaction. The rate of C(6)H(6) activation by [Cp(PMe(3))Ir(Me)CH(2)Cl(2)][BAr(f)] is substantially faster than [Cp(P(OMe)(3))Ir(Me)CH(2)Cl(2)][BAr(f)]. Density functional theory computations suggest that this is due to a less favorable pre-equilibrium for dissociation of the dichloromethane ligand in the trimethyl phosphite complex, rather than to a large electronic effect on the C [bond] H oxidative addition transition state. Because of these combined effects, the overall rate of arene activation is increased by electron-donating substituents on both the substrate and the iridium complex.

Thin film pyrolysis was used to thermally crack asphaltene molecules into their constituent building blocks at 500 °C. By using a thin film of liquid of ca. 20 μm, the cracked products were rapidly released into a much colder sweep gas stream to quench the reactions and minimize further decomposition. The liquid products were condensed and collected, with over 91% material balance on the recovery of gas, liquid, and coke product. Simulated distillation of the condensed liquid products showed a wide range of compounds with boiling points up to more than 700 °C produced in various stages of the reaction. Less than 1% of the original mass of the asphaltenes was released in the form of light gases such as methane and ethane. The liquid components boiling below 538 °C comprised 15–20% of the initial asphaltenes, and contained a wide range of chemical structures including paraffins, olefins, naphthenes, aromatics, thiophenes and sulfides, and nitrogen-containing compounds, identified by gas chromatography–field ionization–time-of-flight mass spectrometry. The ring groups were substituted with a range of alkyl side chains. Asphaltenes from a range of different crude oils gave similar results. The recovery of the building blocks was limited by the reaction conditions, because rereaction of the heavy products generated more light fragments. 13C NMR spectroscopy of the feed and products of thermal cracking of C7 asphaltenes showed a 10–26% increase in the aromatic or double-bonded carbon contents of the products compared to the feed, consistent with yields of toluene-insoluble coke in the range of 50%. The diverse components in the cracked products, with paraffins accounting for a small fraction of the total mass, are consistent with a significant concentration of complex structures attached by bridges in the asphaltene fraction.

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A mechanistic study of the stoichiometric and catalytic H/D exchange reactions involving cationic iridium complexes is presented. Strong evidence suggests that both stoichiometric and catalytic reactions proceed via a monohydrido-iridium species. Stoichiometric deuterium incorporation reactions introduce multiple deuterium atoms into the organic products when aryliridium compounds CpPMe(3)Ir(C(6)H(4)X)(OTf) (X = H, o-CH(3), m-CH(3), p-CH(3)) react with D(2). Multiple deuteration occurs at the unhindered positions (para and meta) of toluene, when X = CH(3). The multiple-deuteration pathway is suppressed in the presence of an excess of the coordinating ligand, CH(3)CN. The compound CpPMe(3)IrH(OTf) (1-OTf) is observed in low-temperature, stoichiometric experiments to support a monohydrido-iridium intermediate that is responsible for catalyzing multiple deuteration in the stoichiometric system. When paired with acetone-d(6)(), [CpPMe(3)IrH(3)][OTf] (4) catalytically deuterates a wide range of substrates with a variety of functional groups. Catalyst 4 decomposes to [CpPMe(3)Ir(eta(3)-CH(2)C(OH)CH(2))][OTf] (19) in acetone and to [CpPMe(3)IrH(CO)][OTf] (1-CO) in CH(3)OH. The catalytic H/D exchange reaction is not catalyzed by simple H(+) transfer, but instead proceeds by a reversible C-H bond activation mechanism.

Collision-induced dissociation Fourier Transform ion cyclotron resonance mass spectrometry (CID-FTICR MS) was developed to determine structural building blocks in heavy petroleum systems. Model compounds with both single core and multicore configurations were synthesized to study the fragmentation pattern and response factors in the CID reactions. Dealkylation is found to be the most prevalent reaction pathway in the CID. Single core molecules exhibit primarily molecular weight reduction with no change in the total unsaturation of the molecule (or Z-number as in chemical formula C(c)H(2c+Z)N(n)S(s)O(o)VNi). On the other hand, molecules containing more than one aromatic core will decompose into the constituting single cores and consequently exhibit both molecular weight reduction and change in Z-numbers. Biaryl linkage, C(1) linkage, and aromatic sulfide linkage cannot be broken down by CID with lab collision energy up to 50 eV while C(2)+ alkyl linkages can be easily broken. Naphthenic ring-openings were observed in CID, leading to formation of olefinic structures. Heavy petroleum systems, such as vacuum resid (VR) fractions, were characterized by the CID technology. Both single-core and multicore structures were found in VR. The latter is more prevalent in higher aromatic ring classes.

The PCP pincer complex, IrH 2 {C 6 H 3 -2,6-(CH 2 P-t-Bu 2 ) 2 } (1) catalyzes the transfer dehydrogenation of primary and secondary alcohols. Dehydrogenation occurs across the C-O bond rather than the C-C bonds and the corresponding aldehydes or ketones are obtained as the sole products arising from the dehydrogenation reactions. Methanol is an exception to this pattern of reactivity and undergoes only stoichiometric dehydrogenation with 1 to give the carbonyl complex, Ir(CO){C 6 H 3 -2,6-(CH 2 P-t-Bu 2 ) 2 } (2). The products are obtained in nearly quantitative yields when the reactions are carried out in toluene solutions. Under the same conditions, 2,5-hexanediol is converted to the annulated product, 3-methyl-2-cyclopenten-1-one which has been isolated in 91% yield in a preparative scale reaction.Résumé : Le complexe PCP en forme de pince, IrH 2 {C 6 H 3 -2,6-(CH 2 P-t-Bu 2 ) 2 } (1) catalyse la réaction de déshydrogé-nation par transfert des alcools primaires et secondaires. La déshydrogénation se fait à travers la liaison C-O plutôt qu'à travers les liaisons C-C et on n'obtient que les aldéhydes et les cétones comme seuls produits de ces réactions de déshydrogénation. Le méthanol est une exception à ce mode de réactivité et il ne subit qu'une déshydrogénation stoechiométrique avec 1 pour conduire à la formation d'un complexe de carbonyle, Ir(CO){C 6 H 3 -2,6-(CH 2 P-t-Bu 2 ) 2 } (2). Lorsqu'on effectue les réactions en solution dans le toluène, les produits sont obtenus en rendements pratiquement quantitatifs. Dans les mêmes conditions, l'hexane-2,5-diol est transformé en produit cyclique, la 3-méthylcyclopent-2-én-1-one qui a été isolée avec un rendement de 91% au cours d'une réaction à l'échelle préparative.

[reaction: see text] Ir(III) complex [Cp(PMe(3))IrMe(CH(2)Cl(2))][BAr(f)] (1) was used to introduce deuterium stoichiometrically into substituted naphthalene/benzene templates and several "drug-like" entities. The exchange process is tolerant of a wide array of functional groups. Labeling of warfarin using subatmospheric pressures of T(2) led to specific activities and total activities rivaling current functional group directed tritium labeling methods. When paired with the appropriate deuterium donor, Cp(PMe(3))Ir(H(3))OTf (4) was found to deuterate a number of organic compounds catalytically.