Chemical Reactivity of Ti⁺ Ion within Ti⁺(CH₂FCH₂OH)_n Clusters

摘要

The ion-molecule reactions that proceed inside Ti⁺(CH₂FCH₂OH)_n heterocluster ions were studied using a laser ablation-molecular beam/reflectron time-of-flight mass spectrometric technique. The mass spectra exhibit a major sequence of cluster ions with the formula Ti⁺(OCH₂CH₂F)_m(CH₂FCH₂OH)_n (m = 1, 2), which is attributed to sequential insertions of Ti⁺ into the O-H bond of ethanol molecules within the heteroclusters, followed by H elimination. The TiO⁺ and TiFOH⁺ ions produced from the reactions of Ti⁺ with CH₂FCH₂OH are interpreted as arising from insertion of Ti⁺ into the C-O bond, followed by C₂H₅F and C₂H₄ elimination, respectively. The observation of Ti⁺(H₂O)(CH₂FCH₂OH)_n ions is attributed to the insertion of Ti⁺ ions into the C-O bond in the ethanol molecules, leading to a モ-H atom transfer and CH₂CHF elimination. This reaction pathway presumably plays an important role as the cluster size increases. Ab initio calculations on the complexes of Ti⁺ with CH₂FCH₂OH molecules show that the minimum energy structure is that in which Ti⁺ is attached to the O and F atoms of fluorinated ethanol, forming a five-membered ring. The formation mechanisms and reaction energetics of the observed heterocluster ions are discussed.