Chemical Insights from High-Resolution X-ray Photoelectron Spectroscopy and ab Initio Theory: Propyne, Trifluoropropyne, and Ethynylsulfur Pentafluoride

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• 作者：Leif J. Sæ ; thre ; Nora Berrah ; John D. Bozek ; Knut J. B//pubs.acs.org/images/gifchars/oslash.gif" border="0">rve ; Thomas X. Carroll ; Edwin Kukk ; Gary L. Gard ; Rolf Winter ; and T. Da
• 刊名：Journal of the American Chemical Society
• 出版年：2001
• 出版时间：October 31, 2001
• 年：2001
• 卷：123
• 期：43
• 页码：10729 - 10737
• 全文大小：96K
• 年卷期：v.123,no.43(October 31, 2001)
• ISSN：1520-5126

文摘

High-resolution carbon 1s photoelectron spectroscopy of propyne (HCCCH₃) shows a spectrumin which the contributions from the three chemically inequivalent carbons are clearly resolved and marked bydistinct vibrational structure. This structure is well accounted for by ab initio theory. For 3,3,3-trifluoropropyne(HCCCF₃) and ethynylsulfur pentafluoride (HCCSF₅), the ethynyl carbons show only a broad structureand have energies that differ only slightly from one another. The core-ionization energies can be qualitativelyunderstood in terms of conventional resonance structures; the vibrational broadening for the fluorinatedcompounds can be understood in terms of the effects of the electronegative fluorines on the charge distribution.Combining the experimental results with gas-phase acidities and with ab initio calculations provides insightsinto the effects of initial-state charge distribution and final-state charge redistribution on ionization energiesand acidities. In particular, these considerations make it possible to understand the apparent paradox that SF₅and CF₃ have much larger electronegativity effects on acidity than they have on carbon 1s ionization energies.