Molybdenum Oxide Cluster Ions in the Gas Phase: Reactions with Small Alcohols

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• 作者：Elena F. Fialko ; Andrey V. Kikhtenko ; and Vladimir B. Goncharov
• 刊名：Organometallics
• 出版年：1998
• 出版时间：January 5, 1998
• 年：1998
• 卷：17
• 期：1
• 页码：25 - 31
• 全文大小：239K
• 年卷期：v.17,no.1(January 5, 1998)
• ISSN：1520-6041

文摘

The gas-phase reactions of molybdenum oxide cluster ionsMo_xO_y⁺(x = 1-3, y = 1-9)with small alcohols have been investigated using Fourier transform ioncyclotron resonancemass spectrometry. The product branch ratios are reported.The reactions ofMo_xO_y⁺withalcohols can be envisioned as proceeding via metal insertion into C-Hand C-O bonds.C-H bond insertion leads to alcohol dehydrogenation and aldehydeelimination, whereasinsertion into the C-O bonds results in alcohol dehydration andformation of metal-alkylgroups. Moreover, an increase of the chain length and branchinglead to C-C bond cleavage.The most intriguing process is the reaction of theMo₃O₉⁺ ion with more than oneCH₃OHmolecule yieldingMo₃O₉(C₂H₅)⁺andMo₃O₉(C₃H₇)⁺ions. TheMo₃O₉CH₃⁺ ionwas found tobe the key intermediate of the polymerization process. Molybdenumoxides are protonatedin the presence of alcohols. The upper and lower limits for theMo_xO_y proton affinitieswereestimated as PA(MoO) < 180 kcal/mol,PA(Mo₂O₄, Mo₂O₅,Mo₃O₈) = 188 ± 8 kcal/mol,PA(MoO₂) = 202 ± 5 kcal/mol, PA(MoO₃,Mo₂O₆, Mo₃O₉) > 207kcal/mol.