顺式-2-亚硝基丙烯（顺式-CH₂═C(CH₃)═N═O）的生成、微波光谱、甲基内旋转势垒及从头算分子轨道计算

Generation, Microwave Spectrum, Barrier to Internal Rotation of Methyl Group, and ab Initio MO Calculation of syn-2-Nitrosopropene, syn-CH(2)&dbond;C(CH(3))&bond;N&dbond;O.

作者信息

Sakaizumi T, Imajo H, Yamasaki R, Usami T, Kawaji S, Abe S, Haraga T, Morii H, Kuze N, Ohashi O

机构信息

Department of Chemistry, Faculty of Science and Technology, Sophia University, 7-1, Kioi-cho, Chiyoda-ku, Tokyo, 102-8554, Japan

出版信息

J Mol Spectrosc. 2000 Nov;204(1):26-35. doi: 10.1006/jmsp.2000.8183.

DOI:10.1006/jmsp.2000.8183

PMID:11034839

Abstract

syn-2-Nitrosopropene was generated, in the gas phase, by chemical reaction of 1-chloro-2-(hydroxyimino)propane with K(2)CO(3) and identified by microwave spectroscopy. The microwave spectrum of the reaction product was observed in the frequency range from 8.0 to 40.0 GHz. The rotational constants (MHz) were determined as A = 8744.09(6), B = 4846.07(2), and C = 3177.84(3) for CH(2)&dbond;C(CH(3))&bond;(14)NO (normal species) and A = 8664.36(5), B = 4822.15(3), and C = 3157.04(3) for CH(2)&dbond;C(CH(3))&bond;(15)NO ((15)N species) in the ground vibrational state. The values of the planar moment (P(cc) = (I(a) + I(b) - I(c))/2) obtained for the normal and (15)N species were 1.525(1) and 1.526(1) u Å(2), respectively. This suggests that the nitrogen atom lies in or is close to the ab inertial plane of the molecule and shows also that only two hydrogen atoms are located symmetrically out of the symmetry plane. The reaction product was determined to be syn-2-nitrosopropene by comparing the observed and calculated rotational constants, kappa (Ray's asymmetry parameter) and r(s) coordinates of the nitrogen atom. The dipole moments (D) were determined to be µ(a) = 2.43(5), µ(b) = 1.12(7), and µ(total) = 2.67(7). The barrier heights of the internal rotation owing to the methyl group of the normal species in the ground and first excited torsional states were determined to be 1750(50) and 1740(50) cal/mol (1 cal/mol = 4.184 J/mol), respectively. The (14)N nuclear quadrupole coupling constants (MHz) were determined to be chi(aa) = 0.25(21), chi(bb) = -7.11(40), and chi(cc) = 6.85(61). Two vibrational excited states were observed and the vibrational frequencies (cm(-1)) of the C-N and C-C torsional modes were determined to be 160(40) and 175(40), respectively. The lifetime of syn-2-nitrosopropene was found to be ca. 2 min in the waveguide cell. Copyright 2000 Academic Press.

摘要

顺式-2-亚硝基丙烯在气相中通过1-氯-2-（羟基亚氨基）丙烷与碳酸钾的化学反应生成，并通过微波光谱法进行鉴定。在8.0至40.0GHz的频率范围内观测到了反应产物的微波光谱。对于处于基振动态的CH₂═C(CH₃)═¹⁴NO（正常物种），其转动常数（MHz）确定为A = 8744.09(6)、B = 4846.07(2)和C = 3177.84(3)；对于CH₂═C(CH₃)═¹⁵NO（¹⁵N物种），其转动常数为A = 8664.36(5)、B = 4822.15(3)和C = 3157.04(3)。正常物种和¹⁵N物种的平面矩（Pcc = (Ia + Ib - Ic)/2）值分别为1.525(1)和1.526(1) u Å²。这表明氮原子位于分子的ab惯性平面内或靠近该平面，同时也表明只有两个氢原子对称地位于对称平面之外。通过比较观测和计算得到的转动常数、κ（雷氏不对称参数）以及氮原子的rs坐标，确定反应产物为顺式-2-亚硝基丙烯。偶极矩（D）确定为µa = 2.43(5)、µb = 1.12(7)和µtotal = 2.67(7)。处于基态和第一激发扭转态的正常物种由于甲基导致的内旋转势垒高度分别确定为1750(50)和1740(50) cal/mol（1 cal/mol = 4.184 J/mol）。¹⁴N核四极耦合常数（MHz）确定为χaa = 0.25(21)、χbb = -7.11(40)和χcc = 6.85(61)。观测到了两个振动激发态，C-N和C-C扭转模式的振动频率（cm⁻¹）分别确定为160(40)和175(40)。发现顺式-2-亚硝基丙烯在波导池中寿命约为2分钟。版权所有2000年学术出版社。