Coupled-cluster study of the rotational and inversion barrier heights, equilibrium geometries and vibrational frequencies of methylamine

Pelegrini, Marina; Roberto‐Neto, Orlando; Machado, Francisco B. C.

doi:10.1016/j.cplett.2005.08.127

Cited by 12 publications

(15 citation statements)

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“…13 All of them belong to the C s symmetry and are shown in Figure 1. Recently, we have optimized the geometry of methylamine using the CCSD(T)/CBS methodology 11 and, in this work, as discussed before, we have re-optimized the structures of all conformers using CCSD(T) methodology, in order to clarify the previous structures of the inversion motion. As one can see, the present results show that, in fact, the previous structures 11 refer to the first-order inversion motion with one imaginary frequency.…”

Section: Resultsmentioning

confidence: 99%

“…11 Kim and Zeroka have shown recently two transition state structures for the inversion mode, with one and two imaginary frequencies, respectively. 13 In order to clarify the previous structures of the inversion motion, 11 we have also re-optimized the structures of all methylamine conformers using the CCSD(T) methodology.…”

Section: Methodsmentioning

confidence: 99%

“…5, 2011 frequencies, and the barrier heights of the internal rotation and inversion motions of methylamine using the CCSD(T) theory with a systematic improvement via cc-pVDZ, cc-pVTZ, cc-pVQZ, and cc-pCVTZ basis sets and also including the contribution of the inner-shell and valenceshell electrons. 11 More recently, Levi et al 12 carried out accurate calculations of the vibrational frequencies, Kim and Zeroka 13 presented new and important results concerning the inversion and rotational barriers and Ducati et al 14 calculated the rotational barrier.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] Methylamine is considered a small molecule from the theoretical point of view, therefore it is appropriate to be studied using high level theoretical quantum chemical methodologies, having received many contributions. [7][8][9][10][11][12][13][14] Lee et al 8 investigated the origin of the structural stability of methylamine concluding that the stereo electronic effect is the major interaction force affecting its stability. Csonka and Sztraka 9 using density functional and post-HartreeFock methodologies showed that the density functional BP86/6-311G(d) method provides reliable results for geometry and vibrational frequencies, as compared with the experimental results.…”

Section: Introductionmentioning

confidence: 99%

“…32,33 Recently, using this methodology, we have investigated the geometries, harmonic vibrational frequencies, and the barrier heights of methylamine. 11 In this work, we are concerned with the calculations of the internal and rotational barrier heights of the methylsubstituted amines, methylamine (CH 3 …”

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confidence: 99%

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A theoretical study of the inversion and rotation barriers in Methyl-substituted Amines

Nascimento¹,

Pelegrini²,

Ferrão³

et al. 2011

J. Braz. Chem. Soc.

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Barreiras de energia para os movimentos de inversão e rotação das moléculas metilamina, dimetilamina e trimetilamina foram calculadas usando a metodologia CCSD(T)//B3LYP com os conjuntos de funções de base de Dunning, cc-pVTZ, cc-pVQZ e cc-pCVTZ. O procedimento de extrapolação para o conjunto de base completa (complete basis set, CBS) e os efeitos da correlação dos elétrons do caroço também foram incluídos nos cálculos das barreiras de energia. Nossos melhores resultados estão em excelente concordâncias com os dados experimentais, indicando que a metodologia utilizada é recomendada para a predição exata de propriedades estruturais e de barreiras de energia de outros sistemas moleculares.Barrier heights of the internal rotation and inversion motions of methylamine, dimethylamine and trimethylamine molecules were calculated with the CCSD(T)//B3LYP methodology in combination with the cc-pVTZ, cc-pVQZ, and cc-pCVTZ basis sets of Dunning. The complete basis set (CBS) extrapolation procedure and core-valence (CV) correlation effects are also examined to the barrier heights. Our best estimate results (CCSD(T)/CBS+CV//B3LYP/cc-pVQZ) are in very good agreement with the experimental data, indicating the use of this methodology to provide accurate predictions of structures and barrier heights for other systems. Keywords: energy barriers, methylamine, dimethylamine, trimethylamine, CCSD//B3LYP IntroductionThe methyl-substituted amines, methylamine (CH 3 NH 2 ), dimethylamine [(CH 3 ) 2 NH], and trimethylamine [(CH 3 ) 3 N] form an interesting group of molecules which are important in organic syntheses and biological processes, as well as they are efficient corrosion inhibitors of aluminum. Beyond their technological importance, these species are rich in structural features presenting large amplitude internal motions, rotation of the methyl groups and internal inversion of the amino group.Methylamine has been extensively studied by experimentalists in which its internal rotation and inversion barrier heights were determined using microwave (MW), infrared (IR) and electron diffraction (ED) experiments. [1][2][3][4][5][6][7] Methylamine is considered a small molecule from the theoretical point of view, therefore it is appropriate to be studied using high level theoretical quantum chemical methodologies, having received many contributions. [7][8][9][10][11][12][13][14] Lee et al. 8 investigated the origin of the structural stability of methylamine concluding that the stereo electronic effect is the major interaction force affecting its stability. Csonka and Sztraka 9 using density functional and post-HartreeFock methodologies showed that the density functional BP86/6-311G(d) method provides reliable results for geometry and vibrational frequencies, as compared with the experimental results. Smeyers and Villa 10 discussed the influence of the zero-point energy correction to the rotation and inversion motions based on the MP2 results, and During and Zheng 7 calculated these motions barriers using B3LYP and MP2 methods. Recently,...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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A theoretical study of the inversion and rotation barriers in Methyl-substituted Amines

Nascimento¹,

Pelegrini²,

Ferrão³

et al. 2011

J. Braz. Chem. Soc.

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Occlusion of Sano conduit with the Amplatzer Vascular Plug: A reliable method for staged elimination of accessory pulmonary blood flow in single ventricle palliation

Gordon

Hashmi

Kuhn

2010

Cathet Cardio Intervent

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Fundamental vibrational frequencies and dominant resonances in methylamine isotopologues by ab initio and density functional theory methods

2007

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Ab initio and density functional theory (DFT) calculations were performed for obtaining fundamental vibrational frequencies of methylamine, CH3NH2, and its deuterated variants CH3ND2, CD3NH2, and CD3ND2. The calculations were carried out using the CCSD(T) coupled cluster approximation with cc-pVTZ and cc-pVQZ basis sets, and by the DFT method with the semiempirical hybrid functional B97-1 with polarization consistent pc-2 and pc-3 basis sets. Reasonable performance of the DFT harmonic and ab initio harmonic calculations was found, which improved considerably upon combination of the harmonic fundamental frequencies with anharmonic corrections from the smaller, pc-2, basis. The computed anharmonic fundamental frequencies of methylamine isotopologues agree very well with the experimental values and represent a useful tool for assignment and analysis of the dominant resonances.

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Coupled-cluster study of the rotational and inversion barrier heights, equilibrium geometries and vibrational frequencies of methylamine

Cited by 12 publications

References 32 publications

A theoretical study of the inversion and rotation barriers in Methyl-substituted Amines

A theoretical study of the inversion and rotation barriers in Methyl-substituted Amines

Occlusion of Sano conduit with the Amplatzer Vascular Plug: A reliable method for staged elimination of accessory pulmonary blood flow in single ventricle palliation

Fundamental vibrational frequencies and dominant resonances in methylamine isotopologues by ab initio and density functional theory methods

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