Crystal structure and Hirshfeld surface analysis of 2-{[(E)-(3-cyclobutyl-1H-1,2,4-triazol-5-yl)imino]methyl}phenol

2-{[(E)-(3-Cyclobutyl-1H-1,2,4-triazol-5-yl)imino]methyl}phenol was synthesized by an eco-friendly microwave-assisted method that is highly selective and efficient. In the crystal, molecules are linked by N—H⋯N and C—H⋯O hydrogen bonds.


Structural commentary
The molecular structure of the title compound, (I), with the atomic numbering scheme is shown in Fig. 1. The asymmetric unit contains three non-planar molecules. The 1,2,4-triazole and phenol-imine rings are twisted with respect to each other, making a dihedral angle of 18.1 (3) for molecule A. The cyclobutyl ring is twisted by 73.9 (3) and 67.8 (4) , with respect to the 1,2,4-triazole, and phenol-imine rings in molecule A. The corresponding angles in molecule B are 18.7 (3), 74.6 (2) and 69.1 (2) and 3.2 (4), 85.9 (2) and 89.1 (2) for molecule C. When these angles for the three molecules are compared, it is observed that there is a harmony between them, as well as significant differences, especially in the angles between the phenol-imine and 1,2,4-triazole rings [3.2 (4) in molecule C but around 18 in A and B] and the phenol-imine cyclobutyl rings [67.8 (4) in A, 69.1 (2) in B and 89.1 (2) in C]. In the molecules, the C N group has a strong electron-withdrawing character, as revealed by the double-bond character of the C N bond [1.276 (6)-1.287 (6) Å ] and the single-bond character of C-O [1.349 (5)-1.355 (6) Å ] in the phenol-imine tautomer. Furthermore, the azomethine C N double bond has an E configuration. These values and other bond lengths and angles (Table 1) -Karawi et al., 2021a,b]. In each molecule, the hydroxyl H atom is involved in a strong intramolecular O-HÁ Á ÁN hydrogen bond (O1-H1Á Á ÁN1, O2-H2Á Á ÁN5 and O3-H3Á Á ÁN9; Table 2) forming an S(6) ring motif.

Figure 2
A partial view of the crystal packing of (I) along the a axis.

Figure 1
The molecular structure of (I) with the atom labelling. Displacement ellipsoids are drawn at the 30% probability level.
(WEFTUX; Cheng et al., 2006). In addition, 1-[(1H-1,2,4triazol-3-ylimino)methyl]-2-naphthol (GILYUX; Jia et al., 2013), which contains a naphthalene fragment instead of benzene, has been reported. In UZOKIE, the hydroxyl-C2 group makes a dihedral angle of 4.48 (3) with the plane of the 1,2,4-triazole ring system. In addition, there are intramolecular O-HÁ Á ÁN contacts in the molecule. Similarly, in WEFTUX, the hydroxyl H atom is involved in an intramolecular O-HÁ Á ÁN hydrogen bond, forming an S(6) ring motif as in the title compound. The two benzene rings (1 and 3) and the triazole ring (2) in WEFTUX, are almost in the same plane, the angles between rings 1 and 2, and between rings 2 and 3 being 3.7 (2) and 3.3 (2) , respectively. This latter angle is 4.58 (8) in PEVXAS. In the structures mentioned above, the twist angles between triazole and phenyl rings are quite small, as in molecule C of (I) [3.2 (4) ]; however, for molecules A and B of the title compound, these angles are over 18 . All compounds were isolated as the phenol-imine (O-HÁ Á ÁN) tautomeric form, as in (I). The bond lengths of the triazole ring in the studied compound are very similar to those in the other 1H-1,2,4-triazole derivatives mentioned above.

Hirshfeld surface analysis
We performed a Hirshfeld surface analysis and generated the associated two-dimensional fingerprint plots (Spackman & Jayatilaka, 2009)  The Hirshfeld surfaces of molecules A, B and C mapped with d norm showing the N-HÁ Á ÁN hydrogen-bonded contacts.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The O-bound H atom was located in a difference-Fourier map and refined with O-H = 0.82 Å , and with U iso (H) = 1.5U eq (O). The N-bound H atom was located in a difference-Fourier map. Its parameters were adjusted to give N-H = 0.86 Å and it was then refined as riding with U iso (H) =1.2U eq (N). The C-bound H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 Å and U iso (H) = 1.2U eq (C) for aromatic and other H atoms, and with C-H = 0.97 Å and U iso (H) = 1.5U eq (C) for methylene H atoms. The crystal studied was refined as a two-component inversion twin. The synthesis of 2-{[(E)-(3-cyclobutyl-1H-1,2,4-triazol-5-yl)imino]meth-yl}phenol, (I). & Cie, 2002); program(s) used to solve structure: SHELXT2017/1 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017/1 (Sheldrick, 2015b); molecular graphics: PLATON (Spek, 2020); software used to prepare material for publication: WinGX (Farrugia, 2012).

2-{[(E)-(3-Cyclobutyl-1H-1,2,4-triazol-5-yl)imino]methyl}phenol
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refined as a two-component inversion twin.