Microwave spectrum and ab initio calculations of indazole

Velino, Biagio; Cané, Elisabetta; Trombetti, A.; Corbelli, G.; Zerbetto, Francesco; Camináti, Walther

doi:10.1016/0022-2852(92)90543-w

Cited by 26 publications

(18 citation statements)

References 16 publications

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“…The ground state constants are identical to the constants found by Velino et al, 20 who confirmed the 1H position via isotopic substitution. Since the differences between the rota-tional constants of the excited state and the ground state are similar to the differences in constants of indole and benzimidazole, we conclude that the indazole in the excited state is in the same form as in the ground state.…”

Section: Discussionsupporting

confidence: 85%

“…For indazole, the vibrationally resolved gas-phase infrared spectrum, 18 and the electronic spectrum 19 have been reported. Precise ground state rotational constants of indazole and its N-D isotopomer have been obtained from microwave spectra reported by Velino et al 20 The same group performed a rotational band contour analysis on the origin band of the S 1 ←S 0 transition of indazole. 21 All aforementioned measurements were performed in a heated cell.…”

Section: Introductionmentioning

confidence: 99%

“…Their conclusion is in agreement with the microwave results, which confirmed the 1H position via isotopic substitution. 20 Recently, we have reported the rotationally resolved fluorescence excitation spectrum of the 0 0 0 band of the S 1 ←S 0 transition of 2H-benzotriazole. 28 The microwave spectra of benzotriazole, recorded in a heated cell 29 and in a jet, 30 have been attributed to the 1H-tautomer.…”

Section: Introductionmentioning

confidence: 99%

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Rotationally resolved ultraviolet spectroscopy of indole, indazole, and benzimidazole: Inertial axis reorientation in the S1(1L b)←S transitions

Berden¹,

Meerts²,

Jalviste³

1995

The Journal of Chemical Physics

109

108

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Inertial axis reorientation in the S 1←S 0 electronic transition of 2pyridone. A rotational Duschinsky effect. Structural and dynamical consequences J. Chem. Phys. 95, 8732 (1991); 10.1063/1.461209 Molecular dynamics study of rotational reorientation of tryptophan and several indoles in water J. Chem. Phys. 94, 3857 (1991); 10.1063/1.460661 The S 1-S 0 transition of indole and Ndeuterated indole: Spectroscopy and picosecond dynamics in the excited state J. Chem. Phys. 91, 6013 (1989); 10.1063/1.457418The rotationally resolved electronic spectrum of indole in the gas phase Rotationally resolved laser induced fluorescence excitation spectra of the S 1 ( 1 L b )←S 0 origin bands of indole, indazole, and benzimidazole have been measured. From these spectra, the rotational constants in both electronic states have been determined. The spectra of all three molecules exhibit ''anomalous'' rotational line intensities. These intensity perturbations are a result of the reorientation, upon electronic excitation, of the inertial axes of the molecule. Intensity analysis of the rotational lines yielded information about the inertial axis reorientation, and the direction of the transition moment vector for each molecule.

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Section: Discussionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rotationally resolved ultraviolet spectroscopy of indole, indazole, and benzimidazole: Inertial axis reorientation in the S1(1L b)←S transitions

Berden¹,

Meerts²,

Jalviste³

1995

The Journal of Chemical Physics

109

108

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“…Indazole is a polar asymmetric bicyclic diazole heterocycle with a dipole moment in the gas phase of 1.76 D. 1 It contains a basic pyridine nitrogen with an intrinsic basicity in the gas phase of 214.2 kcal/mol and an acidic pyrrole nitrogen with an intrinsic basicity in protonated form of 348.4 kcal/mol. 2 The fact that these two nitrogen sites are located in adjacent positions in the molecular structure (see Scheme 1) allows indazole at low concentrations in mildly acid or basic media to form 1H and 2H tautomers via acid-base interactions (see Scheme 1), [3][4][5][6][7][8][9][10] as well as symmetrical dimers by hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

On the solvatochromism, dimerization and tautomerism of indazole

Catalán¹

2013

Arkivoc

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A careful study of the solvatochromism of indazole was for the first time conducted in this work. The study revealed that indazole solvatochromism is governed mainly by the polarizability of the medium and, to a lesser extent, by its acidity and basicity. Based on the results of the solvatochromic analysis and their processing with Abe's model, this polar compound undergoes no significant change in dipole moment from its ground electronic state to its first excited state, which contradicts the predictions of other authors. Indazole dimerizes in both 2-methylbutane and 1-chlorobutane. However, neither its monomer nor its dimer undergoes tautomerization to 2H-indazole in the ground state in response to an increase in dipolarity of the medium. Also, based on experimental evidence, no tautomerization occurs in the first excited singlet or triplet of the compound.

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“…Note that the 15 N chemical shifts are very sensitive to hydrogen bonds and, obviously, to protonation. ) 3524 (n NH gas) [4] Source: [11] X-ray (CSD) [12] PYRZOL INDAZL 1 H NMR Source: [13] Source: [13,14] 13 C NMR Source: [15] Source: [16] 15 N NMR Source: [17] Source: [ Source: [22] Source: [23] Best theoretical calculations Source: [24] Source: [25] Aromaticity (benzene ¼ 0.991) 0.900: [26] 0.808: [26] a) a) Naphthalene: 0.811, 2H-indazole: 0.792 (using as criteria the HOMA) [27]. 111.9 NMR information on the non-aromatic derivatives of pyrazoles is very abundant, particularly on D 2 -pyrazolines and on pyrazolones [4,7].…”

Section: General Reactivitymentioning

confidence: 99%