Synthesis and Microwave Spectrum of Vinyl Isoselenocyanate (H2C鈺怌HNCSe), a Compound with a Quasilinear CNCSe Chain
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- 作者：Harald M酶llendal ; Svein Samdal ; Arne Joakim C. Bunkan ; Jean-Claude Guillemin
- 刊名：The Journal of Physical Chemistry A
- 出版年：2012
- 出版时间：April 26, 2012
- 年：2012
- 卷：116
- 期：16
- 页码：4074-4081
- 全文大小：273K
- 年卷期：v.116,no.16(April 26, 2012)
- ISSN：1520-5215
文摘
The first 伪,尾-unsaturated isoselenocyanate, vinyl isoselenocyanate (H2C鈺怌HNCSe), has been synthesized, and its microwave spectrum has been investigated in the 11.5鈥?7.0 GHz spectral range. The microwave work was augmented by quantum chemical calculations using four different methods, namely, CCSD(T), CCSD, B3LYP, and M062X, with the cc-pVTZ basis set. It is generally assumed that two rotamers having the isoselenocyanide group in an antiperiplanar or a synperiplanar position can exist for this compound. However, these four methods all predict that there is only one rotameric form of the molecule, namely, the antiperiplanar form. The CNC angle of the antiperiplanar rotamer is calculated to vary from 151掳 to 170掳 depending on the quantum chemical methodology. CCSD(T) and B3LYP potential functions of the in-plane CNC bending vibrations were calculated. These functions have one shallow minimum corresponding to the antiperiplanar form. The spectra of the ground and one vibrationally excited state of this rotamer were assigned. Spectral searches for the synperiplanar form were performed but were not successful, so this form must have a relatively high energy, if it exists at all. The vibrationally excited state is presumably the lowest in-plane bending vibration of the CNC angle. Relative intensity measurements yielded a very low frequency of 18(25) cm鈥? for this vibration. The large-amplitude vibration of this mode suggests that this compound should rather be regarded as having a quasilinear CNCSe link of atoms than a rigid, bent antiperiplanar form.