Dimers of Perhaloacetyl Cyanides: CClF2C(O)OC(CN)2CClF2 and CF3C(O)OC(CN) 2CF3. Preparation, Properties, and Spectroscopy

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• 作者：Luis A. Ramos ; Sonia E. Ulic ; Rosana M. Romano ; Helmut Beckers ; Helge Willner ; Maofa Ge ; Shengrui Tong ; Carlos O. Della V茅dova
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：March 6, 2014
• 年：2014
• 卷：118
• 期：9
• 页码：1721-1729
• 全文大小：425K
• 年卷期：v.118,no.9(March 6, 2014)
• ISSN：1520-5215

文摘

The vapor of the new compound 1,1-dicyano-2-chloro-2,2-difluoroethyl chlorodifluoroacetate, CClF₂C(O)OC(CN)₂CClF₂ and of the known 1,1-dicyano-2,2,2-trifluoroethyl trifluoroacetate, CF₃C(O)OC(CN)₂CF₃, were investigated using vibrational spectroscopy tools. The existence of rotational isomerism was confirmed for CClF₂C(O)OC(CN)₂CClF₂ when the matrix isolated compound was examined in combination with the computational results applying quantum chemical models. From the four conformers gauche-syn-gauche, gauche-syn-anti, syn-syn-anti, syn-syn-gauche (the used nomenclature is with respect to the (ClC鈥揅(O)), ((O)C-OC), and (OC鈥揅Cl) torsion angles, respectively) predicted for CClF₂C(O)OC(CN)₂CClF₂ the first two forms can be evidenced using Ar-matrix IR spectroscopy, with the first one being the most abundant at room temperature. On the other side, the results obtained for CF₃C(O)OC(CN)₂CF₃ reveals the existence of only one syn-syn-anti form. CClF₂C(O)OC(CN)₂CClF₂ melts at 鈭?0 掳C and its vapor pressure was fitted by the equation ln p = 鈭?732.6 (1/T) + 10.75 (p [Atm], T [K]) in the range 鈭?0 to 20 掳C. Its extrapolated boiling point is 167 掳C. The first ionization potentials occur for CClF₂C(O)OC(CN)₂CClF₂ and CF₃C(O)OC(CN)₂CF₃ at 12.13 and 12.43 eV, respectively, and were attributed to the ejection of electrons formally located at the carbonylic oxygen lone-pair electrons (n_O). The proposed interpretation of the photoelectron spectrum is consistent with related molecules reported previously, and also with the prediction of Outer Valence Green鈥檚 Functions (OVGF).