Department of Chemistry, Amherst College, P.O. Box 5000, Amherst, Massachusetts 01002-5000, USA.
J Chem Phys. 2009 Nov 28;131(20):204301. doi: 10.1063/1.3250865.
Fourier transform microwave rotation spectra in the 7-21 GHz region are obtained for the complex formed between 1,1-difluoroethylene and hydrogen fluoride, including the normal isotopomer and two singly substituted (13)C species obtained in natural abundance. Spectra are also obtained for the analogous three species formed using deuterium fluoride. Analysis of the spectra provides rotational and hyperfine constants that are used, in combination with information from the analogous complex, 1,1-difluoroethylene-acetylene, to determine a structure for CH(2)CF(2)-HF. This structure is similar to that obtained for vinyl fluoride-HF [G. C. Cole and A. C. Legon, Chem. Phys. Lett. 400, 419 (2004)] in that a primary, hydrogen bonding interaction exists between the HF donor and a F atom acceptor on the 1,1-difluoroethylene moiety, while a secondary interaction occurs between the F atom on the HF molecule and the H atom cis to the hydrogen-bonded F atom on the substituted ethylene and causes the hydrogen bond to deviate from linearity. A comparison of the structures of 1,1-difluoroethylene complexes with the protic acids HF, HCl, and HCCH demonstrates that the hydrogen bond length increases with decreasing gas-phase acid strength, whereas a comparison of HF complexes with vinyl fluoride, 1,1-difluoroethylene, and 1,1,2-trifluoroethylene indicates that the nucleophilicity of the F atoms decreases with increasing fluorine substitution, but that the secondary interaction length is remarkably similar in all three complexes.
在 7-21 GHz 区域获得了 1,1-二氟乙烯与氟化氢形成的复合物的傅里叶变换微波旋转光谱，包括在天然丰度下获得的正常同位素体和两种单取代的 (13)C 物种。还获得了使用氟化氘形成的类似的三种物种的光谱。对光谱的分析提供了旋转和超精细常数，这些常数与类似复合物 1,1-二氟乙烯-乙炔的信息结合使用，用于确定 CH(2)CF(2)-HF 的结构。该结构与乙烯基氟化物-HF [G. C. Cole 和 A. C. Legon，Chem. Phys. Lett. 400, 419 (2004)] 的结构相似，因为在 1,1-二氟乙烯部分上，HF 供体和 F 原子受体之间存在主要的氢键相互作用，而 HF 分子上的 F 原子与取代乙烯上与氢键合的 F 原子相邻的 H 原子之间发生次要相互作用，导致氢键偏离线性。1,1-二氟乙烯复合物与质子酸 HF、HCl 和 HCCH 的结构比较表明，氢键长度随气相酸强度的降低而增加，而 HF 与乙烯基氟化物、1,1-二氟乙烯和 1,1,2-三氟乙烯的复合物比较表明，F 原子的亲核性随氟取代的增加而降低，但在所有三个复合物中，次级相互作用长度非常相似。
