Study of the Gas-phase Chemistry of Y2+ with Small Alkanes

Abstract

Reactions of Y2+ with C1–C6 alkanes have been examined using a Fourier transform mass spectrometer. Due to the moderate second ionization energy of yttrium, 12.4 eV, mixtures of charge-transfer, hydride-transfer, carbanion-transfer, dehydrogenation and alkane-loss products are observed. There is no observable reaction with methane. The predominant product from the reactions with ethane, propane and butane is YC2H42+. Since Y2+ has only one valence electron, oxidative addition to form two covalent bonds to the metal center is not possible, and alternative multicentered mechanisms are proposed. YC2H42+ undergoes displacement reactions with propane and larger alkanes, indicating that electrostatic forces are mainly involved in the bonding of YC2H42+ and other dication products studied, in agreement with theoretical calculations of Bauschlicher and co-workers. In addition to charge- and hydride-transfer, CH3− and C2H5− transfers are also observed in reactions with propane and butane. Charge- and hydride-transfer results are in qualitative agreement with a simple curve-crossing model. © 1997 John Wiley & Sons, Ltd.