Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo , P.O. Box 1033 Blindern, NO-0315 Oslo, Norway.
J Phys Chem A. 2013 Jun 20;117(24):5073-81. doi: 10.1021/jp403374k. Epub 2013 Jun 6.
The microwave spectrum of cyclopropylmethyl isocyanide, C3H5CH2NC, has been investigated in the 25-75 GHz spectral range. The spectra of two conformers were assigned. The H-C-C-N chain of atoms is antiperiplanar in the conformer denoted ap and synclinal in the sc rotamer. The sc conformer tends to be slightly more stable than the ap form. The internal energy difference was determined to be Eap - Esc = 0.2(7) kJ/mol from relative intensity measurements. The spectra of the ground vibrational state and six vibrationally excited states belonging to two different normal vibrations were assigned for sc. The frequencies of these two modes were determined by relative intensity measurements. The dipole moment of this conformer was determined to be μa = 12.16(6), μb = 5.91(4), μc = 0 (preset), and μtot = 13.52(6) × 10(-30) C m [4.05 (2) debye]. The spectra of the ground and of two vibrationally excited states belonging to the torsion and lowest bending vibration were assigned for ap. The microwave work was supported by quantum chemical calculations at the CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory. Most, but not all, of the theoretical predictions are in good agreement with experiment.
环丙甲基异氰酸酯（C3H5CH2NC）的微波光谱在 25-75GHz 光谱范围内进行了研究。分配了两种构象体的光谱。在表示 ap 的构象体中，原子的 H-C-C-N 链呈反式平面，在 sc 旋转异构体中呈顺式弯曲。sc 构象体倾向于比 ap 形式略微稳定。通过相对强度测量确定内部能量差为 Eap - Esc = 0.2(7) kJ/mol。为 sc 分配了基频振动态和六个属于两个不同正则振动的振动激发态的光谱。这些两种模式的频率通过相对强度测量确定。确定此构象体的偶极矩为 μa = 12.16(6)，μb = 5.91(4)，μc = 0（预设）和 μtot = 13.52(6)×10(-30) C m [4.05 (2) 德拜]。为 ap 分配了基频和两个属于扭转和最低弯曲振动的振动激发态的光谱。微波工作得到了 CCSD/cc-pVTZ 和 B3LYP/cc-pVTZ 理论水平的量子化学计算的支持。大多数，但不是全部，理论预测与实验吻合良好。
