Raman and infrared, microwave spectra, conformational stability, adjusted r0 structural parameters, and vibrational assignments of cyclopentylamine

被引:2
作者
Darkhalil, Ikhlas D. [1 ]
Klaassen, Joshua J. [1 ]
Nagels, Nick [2 ]
Herrebout, Wouter A. [2 ]
van der Veken, Benjamin J. [2 ]
Gurusinghe, Ranil M. [3 ]
Tubergen, Michael J. [3 ]
Durig, James R. [1 ]
机构
[1] Univ Missouri, Dept Chem, Kansas City, MO 64110 USA
[2] Univ Ctr Antwerpen, Dept Chem, B-2020 Antwerp, Belgium
[3] Kent State Univ, Dept Chem, Kent, OH 44242 USA
关键词
cyclopentylamine; xenon solutions; conformational stability; vibrational assignment; Raman; AB-INITIO CALCULATIONS; NORMAL-COORDINATE ANALYSIS; XENON SOLUTIONS; PYRROLIDINE; EQUILIBRIUM; EQUATORIAL; MOLECULES;
D O I
10.1002/jrs.4467
中图分类号
O433 [光谱学];
学科分类号
0703 ; 070302 ;
摘要
Fourier transform microwave spectrum of cyclopentylamine, c-C5H9NH2 has been recorded, and seven transitions have been assigned for the most abundant conformer, and the rotational constants have been determined: A = 4909.46(5), B = 3599.01(4), and C = 2932.94(4). From the determined microwave rotational constants and ab initio MP2(full)/6-311 + G(d,p) predicted structural values, adjusted r(0) parameters are reported with distances (angstrom): rC(alpha)-C-beta = 1.529(3), rC(beta)-C-gamma = 1.544(3), rC(gamma)-C-gamma = 1.550(3), rC(alpha)-N = 1.470(3), and angles (degrees) angle CCN = 108.7(5), angle C beta C alpha C beta = 101.4(5), and tau C beta C alpha C beta ' C gamma ' = 42.0(5). The infrared spectra (4000-220 cm(-1)) of the gas have been recorded. Additionally, the variable temperature (-60 to -100 degrees C) Raman spectra of the sample dissolved in liquefied xenon was recorded from (3800-50 cm(-1)). The four possible conformers have been identified, and their relative stabilities obtained with enthalpy difference relative to t-Ax of 211 +/- 21 cm(-1) for t-Eq >= 227 +/- 22 cm(-1) for g-Eq >= 255 +/- 25 cm(-1) for g-Ax. The percentage of the four conformers is estimated to be 53% for the t-Ax, 11 +/- 1% for t-Eq, 20 +/- 2% for g-Ax and 16 +/- 2% for g-Eq at ambient temperature. The conformational stabilities have been predicted from ab initio calculations by utilizing several different basis sets up to aug-cc-pVTZ from both MP2(full) and density functional theory calculations by the B3LYP method. Vibrational assignments have been provided for the observed bands for all four conformers, which are predicted by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities, and depolarization ratios for all of the conformers. The results are discussed and compared to the corresponding properties of some related molecules. Copyright (c) 2014 John Wiley & Sons, Ltd.
引用
收藏
页码:392 / 406
页数:15
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