The study of the electronic structure and reactivity of 5-(adamantane-1-yl)-4r-1,2,4-triazole-3-thioles derivatives.
DOI:
https://doi.org/10.11603/1811-2471.2015.v23.i2-3.5254Abstract
SUMMARY. The electronic absorption spectra of 5-(adamantane-1-yl)-4-phenyl-1,2,4-triazole-3-thiole (I) and 5-(adamantane-1-yl)-4-methyl-1,2,4-triazole-3-thiole (II) in solvents of different polarity (water, 95 % ethanol, 0.1 M HCl, 0.1 M H2SO4, 0.1 M NaOH, n-hexane) are studied. It is established that the absorption band of compound I is characterized by the presence of only one maximum of the average intensity in the range from 250 to 262 nm, while compound II is in the range from 236 to 255 nm. Considering the chemical structure of the studied compounds and their absorption’s spectra it can be concluded that the absorption band of the compound I is the result of π→πx – transition ‘s applying of 1,2,4-triazole cycle at 1Lb – a strip of phenolic radical. The absorption band of compound II is caused only by π→ πx – transitions in the parental chromophore, namely in 1,2,4-triazole. The use of the Extended Hückel method based on the linear combination of atomic orbitals in accordance with the program Chemoffice Free Trial 11.0.1 allowed us to conduct forecasting of the investigated compounds on the basis of quantum chemical calculations of their atoms’ charges. The calculations led to the conclusion that 1,2,4- triazole cycle of compound I is π – redundant due to the substituents’ influence, which are located in the position of 3-SH – (-Ι, +M), 4-phenyl – (-Ι, +M), 5-adamantyl (+I). The acidic nature of SH centre appears due to the Elektron-acceptor effect of triazole ring. The sulphur atom shows a negative inductive effect (-I), but mesomeric effect is positive (+M) +M-I. The sulfur atom has a deficiency of electron density (+ 0,0314774), but a charge (+0,0232012) is focused on the hydrogen atom of the thiol group, resulting the reaction of alkylation (SF) occurs at SH – acidic center. Considering the quantum-chemical calculations of atomic charges of compound II can be concluded that the presence of methyl substituent in position 4 affects the distribution of electron density. Thus a methyl radical shows a positive inductive effect (+I).
Key words: UV spectra, electronic structure, reactivity, derivatives of 5-(adamantane-1-yl)-4R-1,2,4-triazole-3-thioles.References
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