MOLECULAR-STRUCTURE AND INTERNAL MOTION OF FORMAMIDE FROM MICROWAVE-SPECTRUM
MOLECULAR-STRUCTURE AND INTERNAL MOTION OF FORMAMIDE FROM MICROWAVE-SPECTRUM
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DOI：
10.1016/0022-2852(74)90274-4
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发表时间：
1974-01-01
影响因子：
1.4
通讯作者：
SORENSEN, GO
中科院分区：
文献类型：
--
作者：
HIROTA, E;SUGISAKI, R;SORENSEN, GO
本文通过对NH_2CHO和ND_2CHO的~（13）C和~（18）O的微波光谱的观测，重新确定了甲酰胺的分子结构。假设分子的平面度为N Hc= 1.0016± 0.003 °，N Ht= 1.0015± 0.003 °，C N = 1.352± 0.012 °，C O = 1.219± 0.012 °，C Ha= 1.098± 0.01 °，N HcNHt= 121.6° ± 0.3°，N HcNC = 118.5° ± 0.5°，δ HtNC = 120.0° ± 0.5°，δ NCO = 124.7° ± 0.3°，δ NCHa= 112.7° ± 2°，δ OCHa= 122.5° ± 2°. King观察到的远红外光谱归属于反转的v = 1 <$0、2 <$1和3 <$2跃迁，ND 2CHO也检测到v = 1 <$0和2 <$1跃迁。用观测到的振动频率确定了两个势能常数V2 = 156 ± 34 cm−1/rad 2和V4 = 398 ± 29 cm−1/rad 4，势能函数的形式为V=V2τ2+V4τ 4，其中τ是氨基的反转角。因此，分子基本上是平面的，在平面构型处没有任何潜在的驼峰。对NH_2CHO和ND_2CHO计算了由反演激发引起的惯性缺陷的变化，与观测结果基本一致。
The molecular structure of formamide has been redetermined by observing the microwave spectra of the13C and18O species of NH2CHO and ND2CHO. Thersstructure calculated assuming the planarity of the molecule is NHc= 1.0016± 0.003 Å, NHt= 1.0015± 0.003 Å, CN = 1.352± 0.012 Å, CO = 1.219± 0.012 Å, CHa= 1.098± 0.01 Å, ∠HcNHt= 121.6° ± 0.3°, ∠HcNC = 118.5° ± 0.5°, ∠HtNC = 120.0° ± 0.5°, ∠NCO = 124.7° ± 0.3°, ∠NCHa= 112.7° ± 2°, and ∠OCHa= 122.5° ± 2°.The strongest satellite of the rotational spectrum is assigned to the first excited state of the amino inversion. The far-infrared spectra observed by King are assigned to thev= 1 ← 0, 2 ← 1, and 3 ← 2 transitions of the inversion, and thev= 1 ← 0 and 2 ← 1 transitions are detected also for the ND2CHO species. The observed vibrational frequencies are used to determine the two potential constantsV2= 156 ± 34 cm−1/rad2andV4= 398 ± 29 cm−1/rad4in the potential function to the inversion of the form,V=V2τ2+V4τ4where τ is the inversion angle of the amino group. The molecule is thus essentially planar without any potential hump at the planar configuration. The changes of the inertia defect by the excitation of the inversion have been calculated approximately for NH2CHO and ND2CHO in fair agreement with the observed.