Theoretical and experimental study of the conformational, structural analysis and vibrational spectra of 1,2-bis(1,2,4-triazole-1-yl)ethane

1,2-Bis(1,2,4-triazole-1-yl)ethane (BTE) was prepared and its crystal structure has been investigated by X-ray analysis. The compound crystallizes in monoclinic space group P21=a with a ¼ 6:805ð3Þ; b ¼ 8:836ð3Þ; c ¼ 6:646ð2Þ A; b ¼ 112:114ð7Þ8; V ¼ 370:2ð2Þ A3; Z ¼ 2; and D ¼ 1:473 Mg=m3: The structure was solved by direct methods and refined to R ¼ 0:0438 and wR2 ¼ 0:1145 by full matrix anisotropic least-squares methods. The molecular geometry and vibrational frequencies of the anti-BTE in the ground state have been calculated using the Hartree–Fock and density functional method (B3LYP) with 6-31 þ G** basis set. The optimized bond lengths obtained by RHF method and bond angles obtained by density functional theory (DFT) method show better agreement with the experimental values. The energy profile was calculated by RHF/6-31 þ G** and DFT B3LYP/6-31 þ G** methods as a function of u½N1–C3–C30 –N10 : The most stable structure of BTE is the anti conformation, which is different in energy by 45.41 and 3.28 kcal/mol for RHF method (by 36.78 and 2.70 kcal/mol for DFT method) from the eclipsed conformation I and gauche conformations (II and IV), respectively. The harmonic vibrations computed of anti-BTE by the RHF and DFT methods are in a good agreement with the observed FTIR spectra data. q 2004 Elsevier B.V. All rights reserved.