14  Organic gas-phase ion chemistry

Reactions of Atomic Metal Anions in the Gas phase: Competition between Electron Transfer, Proton Abstraction and Bond Activation

“…Oxidative addition/reductive elimination involves the loss of stereochemistry, while bimolecular nucleophilic substitution reactions, notably S N 2 reactions, involve the inversion of stereochemistry. These reactions have been explored extensively in solution and the gas phase. − The differences between solution and gas-phase behavior have been used to explore the role of the solvent in these reactions. While organic nucleophiles and substrates have been extensively studied, the use of metallic nucleophilic systems has been limited to a small class of organometallic complexes, both in solution and the gas phase.…”

Organic gas-phase ion chemistry

“…These contributions address ionic hydrogen bonds, 25 the role of water in ionic and radical processes, 26 molecular and chiral recognition, 27,28 ion-ion chemistry, 29 velocity modulation spectroscopy of ions, 30 infrared spectroscopy of metal ion complexes, 31 hydration of small peptides, 32 all metal aromaticity, 33 catalytic reactions of small metal clusters, 34 divalent metal complex ion reactivity, 35 and fundamental organic reaction studies carried out in a quadrupole ion trap. 36 The organization of this review is in keeping with recent contributions to this series by Wenthold, [37][38][39] O'Hair, 40,41 and Gronert, 42 and is presented in the following broad categories: Biological chemistry, Thermochemistry, Ion spectroscopy, Reactions of anions, cations, and radical ions, Nucleophilic substitution, addition, and elimination, Reactions of organic compounds with small inorganic ions, Chiral recognition and host-guest chemistry, and Cluster chemistry.…”

“…This maybe due to a weaker basicity as a result of chromium's greater electronegativity. Fragmentation of 21 (R ¼ Bu) via energetic collisions results in the oxidative loss of butanal for all three complexes as required in the second step of the catalytic cycle [eqn (37)], but the tungsten containing species also affords butene in a non-productive pathway [eqn (38)]. Chromium is a stronger oxidant than molybdenum or tungsten, and its presence is helpful in this step.…”

“…Chromium is a stronger oxidant than molybdenum or tungsten, and its presence is helpful in this step. Oxidation of the reactive portion of 22 with nitromethane completes the catalytic cycle and regenerates the starting ion [eqn (39)], but only the tungsten containing ion was found to react. These data indicate that the metal center plays a large role in the observed chemistry and only the heterobinuclear [MoWO 6 (OH)] À ion works as a catalyst.…”

Gas-Phase Reactions of Bis(η5-cyclopentadienyl)methylzirconium Cations with Ketones and Aldehydes

“…16 The intrinsic reactivity of hydroxyzirconocenes was also studied as a model for metal-hydroxide complex ion reactions with a range of compounds. 17 Despite rapid growth in the gas-phase chemistry of organometallic complexes, especially metal ions, [18][19][20][21] and the importance of metallocene catalysis, gas-phase studies of metallocene ions are still rather scarce. The purpose of the present work was to gain a deeper understanding of the reaction mechanisms for electrophilic early-transition-metal metallocenes and to attempt a generalization of the gas-phase reactions with unsaturated compounds.…”