Miguel Fábio Balbino, Dantas Juliana Arantes, Amorim Stefany, Andrade Gustavo F S, Costa Luiz Antônio Sodré, Couri Mara Rubia Costa
NUPEQ - Núcleo Multifuncional de Pesquisas Químicas, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
NEEM - Laboratório de Nanoestruturas Plasmônicas, Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
Spectrochim Acta A Mol Biomol Spectrosc. 2016 Jan 5;152:318-26. doi: 10.1016/j.saa.2015.07.041. Epub 2015 Jul 8.
In the present study a series of novel pyrazolines derivatives has been synthesized, and their structures assigned on the basis of FT-Raman, (1)H and (13)C NMR spectral data and computational DFT calculations. A joint computational study using B3LYP/6-311G(2d,2p) density functional theory and FT-Raman investigation on the tautomerism of 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carbothioamide and 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carboxamide are presented. The structures were characterized as a minimum in the potential energy surface using DFT. The calculated Raman and NMR spectra were of such remarkable agreement to the experimental results that the equilibrium between tautomeric forms has been discussed in detail. Our study suggests the existence of tautomers, the carboxamide/carbothioamide group may tautomerize, in the solid state or in solution. Thermodynamic data calculated suggests that the R(CS)NH2 and R(CO)NH2 species are more stable than the R(CNH)SH and R(CNH)OH species. Additionally, results found for the (1)H NMR shifting, pointed out to which structure is present.
在本研究中，合成了一系列新型吡唑啉衍生物，并根据傅里叶变换拉曼光谱、¹H和¹³C核磁共振光谱数据以及密度泛函理论（DFT）计算确定了它们的结构。本文介绍了一项联合计算研究，该研究使用B3LYP/6-311G(2d,2p)密度泛函理论，对3-(4-取代苯基)-4,5-二氢-5-(4-取代苯基)吡唑-1-碳硫酰胺和3-(4-取代苯基)-4,5-二氢-5-(4-取代苯基)吡唑-1-甲酰胺的互变异构现象进行了傅里叶变换拉曼光谱研究。利用DFT将结构表征为势能面上的最小值。计算得到的拉曼光谱和核磁共振光谱与实验结果非常吻合，因此对互变异构体形式之间的平衡进行了详细讨论。我们的研究表明，在固态或溶液中，互变异构体是存在的，甲酰胺/碳硫酰胺基团可能会发生互变异构。计算得到的热力学数据表明，R(CS)NH₂和R(CO)NH₂物种比R(CNH)SH和R(CNH)OH物种更稳定。此外，¹H核磁共振位移的结果指出了存在哪种结构。
