Synthesis of organo-uranium(II) species in the gas-phase using reactions between [UH]+ and nitriles

One challenge in the quest to map the intrinsic reactivity of model actinide species has been the controlled synthesis of organo-actinide ions in the gas phase. We report here evidence that a series of gasphase, s-bonded [U-R](+) species (where R = CH3, C2H3, C2H5, C3H7, or C5H6) can be generated for subsequent study of ion-molecule chemistry by using preparative tandem mass spectrometry (PTMSn) via ion-molecule reactions between [UH](+) and a series of nitriles. Density functional theory calculations support the hypothesis that the [U-R](+) ions are created in a pathway that involves intramolecular hydride attack and the elimination of neutral HCN. Subsequent reactivity experiments revealed that the [UCH3](+) readily undergoes hydrolysis, yielding cationic uranium hydroxide ([UOH](+)) and methane (CH4). Other possible reaction pathways, such as the spontaneous rearrangement to [HUvCH(2)](+), are shown by theoretical calculations to have energy barriers, strengthening the evidence for the formation of a sigma-bonded [U-CH3](+) complex in the gas-phase.