Transition metal ions exothermic reactions

Exothermic Reactions of Transition Metal Ions with Hydrocarbons. Cross sections for the formation of product ions resulting from the interaction of Ni+ with n-butane are shown in Figure 6 for a range of relative kinetic energies between 0.2 and 4 eV. In contrast to the results shown in Figure 3, several products (reactions 6-8) are formed with large cross section at low energies. These cross sections decrease with... 

On the other hand, it has proved possible to activate a C-C bond by using bare ( naked ) transition metal ions, generated by various ionization methods in the gas phase [165]. Using an ion-beam instrument, for example, Armentrout and Beauchamp [166] were able to show that the reaction of Co+ with -butane gives C0C2H4. An exothermic and quite facile C-C insertion by the metal is thought... 

Higher alkanes undergo exothermic gas-phase reactions with some transition-metal ions. Co" and Ni insert into the C—C and C—H bonds of propane to give oxidative addition products which eliminate CH4 and H2, respectively. The relative amount of methane formed increases with the amount of branching in the alkane . LaFe" reacts with alkanes (except methane) giving mainly dehydrogenation products, but with some C—C cleavage, particularly in reactions with cyclopropane and cyclobutane... 

The reaction is exothermic, AHrxn being -23.66 kcal. In basic solution, such decomposition occurs very rapidly. Also, decomposition is catalyzed rapidly by trace amounts of transition metals. In aqueous media, Fe2+ ion decomposes H2O2 forming Feiii(OH)2" and OH ions, while in acetonitrile a ferryf ion, Fe02 " is formed initially, but it reverts to Fe + ion. The reactions are ... 

Beauchamp and Armen trout studied the reaction of Co with isobutane in an ion beam apparatus connected to a mass spectrometer. They were able to see very similar chemistry to that observed by Larsen and Ridge. Co reacts with C-H and C-C bonds exothermically, the latter being preferred on thermodynamic grounds. They showed in a later study, performed with deuterated propane derivatives, that all possible transformations involve insertion into both primary and secondary C-H bonds through 3c-2e transition states. Similar transition states were found by ab initio calculations in the reaction of methane with second-row transition metals by Siegbahn et al. The results of subsequent studies are summarized in reviews. ... 

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