Experimental nuclear magnetic resonance spectral assignments, H-1/C-13 GIAO calculations, molecular structure and molecular resonance states of 4-Methyl-1H-Indazole-5-Boronic acid

摘要

Some molecules such as 4-Methyl-1H-Indazole-5-Boronic Acid (4M1HI5BA) have different resonance states under different temperatures. Henceforth, it is difficult to characterize these type of molecules. Since, in general one or more hydrogen atoms move through the molecule and molecular symmetry changes. The possible 3 different resonance forms and molecular structure of 4-Methyl-1H-Indazole-5-Boronic Acid (4M1HI5BA) molecule have been studied experimentally using nuclear magnetic resonance (NMR) spectroscopy. C-13 cross-polarization magic-angle spinning, B-11, H-1, C-13, COSY, HMBC, NOESY, T-1 relaxation time NMR spectra of 4M1HI5BA molecule have been reported. Moreover, H-1 NMR spectra were obtained in different solvents and under variable temperatures. Results from experimental datas showed that title molecule has three different resonance states and these resonance states change with different temperature. In addition, H-1 and C-13 chemical shift values were calculated by CIAO method and computed values were compared with experimentally obtained values. There are good agreement between experimental and theoretical chemical shift values. (C) 2017 Elsevier B.V. All rights reserved.