Molecular and crystal structure characteristics of 2-phenylaminotetrahydro-1,3-thiazepine hydrochloride and 2-phenyliminohexahydro-1,3-thiazepine European Journal of Chemistry 14 (1) (2023) 9-15 European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2023 The Authors – Atlanta Publishing House LLC – Printed in the USA. This work is published and licensed by Atlanta Publishing House LLC – CC BY NC – Some Rights Reserved. https://dx.doi.org/10.5155/eurjchem.14.1.9-15.2345 European Journal of Chemistry View Journal Online View Article Online Molecular and crystal structure characteristics of 2-phenylaminotetrahydro- 1,3-thiazepine hydrochloride and 2-phenyliminohexahydro-1,3-thiazepine Mukhriddin Umirov 1,*, Alisher Eshimbetov 2, Jamshid Ashurov 2, Kambarali Turgunov 3,4 and Khamid Khodjaniyazov 2 1 Department of Chemistry of Natural Compounds, Faculty of Chemistry, National University of Uzbekistan, Tashkent, 100174, Uzbekistan 2 Laboratory of Complex Compounds, Institute of Bioorganic Chemistry, Uzbek Academy of Sciences, Tashkent, 100125, Uzbekistan 3 Laboratory of Physical Methods of Research, Institute of The Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent, 100170, Uzbekistan 4 Department of Natural-Mathematical Science, Turin Polytechnic University in Tashkent, Tashkent, 100095, Uzbekistan * Corresponding author at: Department of Chemistry of Natural Compounds, Faculty of Chemistry, National University of Uzbekistan, Tashkent, 100174, Uzbekistan. e-mail: chemnatproduct.nuuz@gmail.com (M. Umirov). 10.5155/eurjchem.14.1.9-15.2345 Received: 15 September 2022 Received in revised form: 18 October 2022 Accepted: 21 October 2022 Published online: 31 March 2023 Printed: 31 March 2023 The current research includes the synthesis and crystallographic characterization of 2- phenylaminotetrahydro-1,3-thiazepine hydrochloride (HPAT) and 2-phenyliminohexa- hydro-1,3-thiazepine (PIT) compounds. 2-Phenylaminotetrahydro-1,3-thiazepine hydro- chloride was synthesized by cyclization of 1-(4-hydroxybutyl)-3-phenylthiourea in an acidic condition. The second compound, 2-phenyliminohexahydro-1,3-thiazepine, was obtained by neutralizing 2-phenylaminotetrahydro-1,3-thiazepine hydrochloride with sodium hydrocarbonate. Both compounds were characterized by the single-crystal X-ray diffraction method. Crystal data for C11H17N2OClS (HPAT): orthorhombic, space group P212121 (no. 19), a = 4.97183(14) Å, b = 15.1169(4) Å, c = 17.7376(5) Å, V = 1333.14(6) Å3, Z = 4, μ(CuKα) = 3.859 mm-1, Dcalc = 1.299 g/cm3, 9243 reflections measured (7.684° ≤ 2Θ ≤ 152.042°), 2749 unique (Rint = 0.0314, Rsigma = 0.0255) which were used in all calculations. The final R1 was 0.0351 (I > 2σ(I)) and wR2 was 0.0911 (all data). Crystal data for C11H14N2S (PIT): monoclinic, space group P21/n (no. 14), a = 9.6303(9) Å, b = 9.8938(6) Å, c = 11.5627(9) Å, β = 103.419(8)°, V = 1071.62(14) Å3, Z = 4, μ(CuKα) = 2.357 mm-1, Dcalc = 1.279 g/cm3, 3938 reflections measured (10.798° ≤ 2Θ ≤ 152.328°), 2172 unique (Rint = 0.0288, Rsigma = 0.0330) that were used in all calculations. The final R1 was 0.0431 (I > 2σ(I)) and wR2 was 0.1219 (all data). The asymmetric unit of HPAT contains one protonated amine, one chlorine anion, and one water molecule. Chlorine anion and water molecules play the role of the bridge in chain formation along the a- and b-axis through H-bonds with N-H hydrogen atoms. Furthermore, the Hirshfeld surface analyses are performed to determine the nature of the intermolecular contacts stabilizing the crystal structures of 2-phenylaminotetrahydro-1,3-thiazepine hydrochloride and 2-phenyliminohexahydro-1,3-thiazepine. X-ray diffraction Hirshfeld surface 2D Fingerprint plots Single crystal structure 1-(4-Hydroxybutyl)-3-phenylthiourea 2-Phenyliminohexahydro-1,3-thiazepine Cite this: Eur. J. Chem. 2023, 14(1), 9-15 Journal website: www.eurjchem.com 1. Introduction The carbon-bridged nitrogen atoms -NH-C(R)=N- are known as the amidine group, which occurs in many biologically active compounds [1-4]. Hydrogenated derivatives of 2-phenyl amino-1,3-thiazoline, 2-phenylamino-1,3-thiazine and 2- phenylamino-1,3-thiazepine belong to one of the classes of compounds that contain an amidine group [4,5]. These compounds have been the subject of many investigations due to the presence of amine-imine tautomeric forms and biological activities [5,6]. 1,3-Thiazepines are studied less than their five- or six-membered analogs. A series of hydrogenated 1,3- thiazepine derivatives have been obtained by Ambartsumova et al. [7-10]], including 2-benzyliminohexahydro-1,3-thiazepine (imine form), which was reported as an amine form (2-benzyl aminotetrahydro-1,3-thiazepine) by Olszenko-Piontkowa and Urbanski [11]. The single-crystal X-ray diffraction method plays an important role to attribute a reaction product to an imine form [8]. Furthermore, the spatial arrangement of the atoms and the conformation of the seven-membered ring, which was obtained by X-ray diffraction analysis [8] or theoretical methods [12], is of great importance for amine-imine tautomeric chemistry. But only a few compounds that include the 1,3-thiazepine ring containing (with Refcodes in CCDC [13]: BEVNEW [14], BEVNIA [14], JEPYOS [15], QIBMET [16], QIBMET01, QIBMET02, QIBMET03, QIBMET04 [17], QOZMUO [18], RENVOV [8], RENVIP [8], and YUKPIE [19]) were characterized by the single-crystal XRD method. All of these deposited structures belong to an imine form. Amine forms of 1,3-thiazepines or their salts have not been deposited in CCDC till nowadays. The accumulated experimental data on the stereochemistry of the seven-membered ring with nitrogen and sulfur atoms can ABSTRACT RESEARCH ARTICLE KEYWORDS https://dx.doi.org/10.5155/eurjchem.14.1.9-15.2345 https://www.eurjchem.com/ https://dx.doi.org/10.5155/eurjchem.14.1.9-15.2345 mailto:chemnatproduct.nuuz@gmail.com http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.14.1.9-15.2345&domain=pdf&date_stamp=2023-03-31 10 Umirov et al. / European Journal of Chemistry 14 (1) (2023) 9-15 2023 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.14.1.9-15.2345 + S N H N HPAT 1 2 3 4 5 6 7 8 1' 2'3' 4' H Cl HCl -H2O -HCl NaHCO3 PIT OH N H S N H HO NH2 N C S S HN N Scheme 1. Synthesis of 2-phenylaminotetrahydro-1,3-thiazepine hydrochloride (HPAT) and 2-phenyliminohexahydro-1,3-thiazepine (PIT). be useful in the theoretical modeling of biologically active derivatives of hydrogenated 1,3-thiazepine. Therefore, in this report, we focused on the seven-membered ring derivatives and the molecular structure of hydrochloride of 2-phenyl aminotetrahydro-1,3-thiazepine (HPAT) and 2-phenylimino hexahydro-1,3-thiazepine (PIT) was determined by the single crystal X-ray diffraction method. Furthermore, Hirshfeld surface analysis was performed to determine the nature of the intermolecular contacts that stabilize the crystal structures of HPAT and PIT. 2. Experimental 2.1. Synthesis of hydrogenated 1,3-thiazepines 2.1.1. 1-(4-Hydroxybutyl)-3-phenylthiourea 1-(4-Hydroxybutyl)-3-phenylthiourea was synthesized by the interaction of phenyl isothiocyanate (PITC) with 4-amino- 1-buthanol according to known methods (Scheme 1) [5,7]. To a solution of 4-aminobutanol-1 (8.91 g, 0.1 mol) in THF (25 mL) added drop-wise of phenyl isothiocyanate (0.1 mol, 13.5 g) in THF (15 mL) with vigorous stirring at a temperature of 15 to 20 °C. The reaction mixture was left to stand for 24 hours at room temperature. Then, the obtained white solids were purified by recrystallization from aqueous ethanol mixture. Yield: 90%. The spectral characteristics were identical to the data from the literature [7]. 2.1.2. Hydrochloride of 2-phenylaminotetrahydro-1,3- thiazepine (HPAT) Cyclization of 1-(4-hydroxybutyl)-3-phenylthiourea in an acidic medium (HCl) was carried out according to the method described in references (Scheme 1) [5,7,11]. 0.05 mol of thiourea were added to 300 mL of concentrated HCl and boiled for 5 h. To the evaporated half-reaction mixture was added 100 mL of water and, upon cooling, neutralized Sodium bicarbonate (0.1 N). The oily product obtained was separated from the reaction mixture. It dissolved in chloroform and was placed in a dark place for evaporation of chloroform. The product was crystallized in chloroform within one week. The yield of HPAT is 53%. 2.1.3. 2-Phenyliminohexahydro-1,3-thiazepine (PIT) 2-Phenyliminohexahydro-1,3-thiazepine was obtained from HPAT. HPAT (3 g, 0.11 mol) was dissolved in water and neutralized with 0.01 N sodium bicarbonate (Scheme 1). The obtained white precipitates were filtered off and dissolved in chloroform. Yield: 96% (2.27 g). The suitable colorless crystals were obtained in chloroform within one week for single-crystal X-ray analysis. 2.2. Single crystal X-ray diffraction analysis Single crystal X-ray diffraction (XRD) data were collected by using CuKα radiation (λ = 1.54184 Å) on a CCD Xcalibur Ruby diffractometer (Oxford Diffraction) at room temperature. Data reduction including multi-scan absorption correction was done using CrysAlisPRO [20]. The structure was solved by a direct method using the SHELXT program [21], integrated into the OLEX2 package [22], and refined by full-matrix least squares using the SHELXL program [23]. All non-H atoms were refined anisotropically. Hydrogen atoms were inserted at calculated positions and constrained with isotropic thermal parameters, except for hydrogen atoms of nitrogen and water molecules, which were located from a Fourier-difference map and refined isotropically. Molecular and crystal structures are plotted using XP [24] and MERCURY program packages [25]. 2.3. Theoretical studies Hirshfeld surfaces and fingerprint plots were calculated for the title compounds based on the crystallographic information file (CIF) using the CrystalExplorer program [26]. 2D finger- print plots displayed using the standard 0.7-2.6 Å view with the de and di distance scales displayed on the graph axes. The function dnorm is a ratio that encloses the distances of any surface point to the nearest interior (di) and exterior (de) atoms and the van der Waals (vdW) radii of the atoms. Hirshfeld surfaces were obtained using a standard (high) surface resolution with the three-dimensional dnorm surfaces mapped over a fixed color scale of -0.492 (red) to 1.265 (blue). Points with a contribution to the Hirshfeld surface are colored by blue for a small contribution and by green to red for points with the greatest contributions. 3. Results and discussion 3.1. Single crystal X-ray diffraction analysis The general reaction scheme for the preparation of hydro- genated 1,3-thiazepines is shown in Scheme 1. The main crystallographic data of both obtained products HPAT and PIT are summarized in Table 1. The molecular structure of HPAT and PIT with atom labeling is presented in Figure 1. HPAT crystallizes in the orthorhombic P212121 space group (Table 1). The asymmetric unit contains one protonated molecule, a chlorine anion, and one water molecule (Figure 1). Umirov et al. / European Journal of Chemistry 14 (1) (2023) 9-15 11 2023 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.14.1.9-15.2345 Table 1. Crystal data and parameters for structure refinement of HPAT and PIT. Parameter/Compound HPAT PIT Empirical formula C11H17N2OClS C11H14N2S Formula weight (g/mol) 260.77 206.30 Temperature (K) 296(2) 293(2) Crystal system Orthorhombic Monoclinic Space group P212121 P21/n a, (Å) 4.97183(14) 9.6303(9) b, (Å) 15.1169(4) 9.8938(6) c, (Å) 17.7376(5) 11.5627(9) β (°) 90 103.419(8) Volume (Å3) 1333.14(6) 1071.62(14) Z 4 4 ρcalc (g/cm3) 1.299 1.279 μ (mm-1) 3.859 2.357 F(000) 552.0 440.0 Crystal size (mm3) 0.25 × 0.22 × 0.16 0.3 × 0.25 × 0.16 Radiation Cu Kα (λ = 1.54184) Cu Kα (λ = 1.54184) 2Θ range for data collection (°) 7.684 to 152.042 10.798 to 152.328 Index ranges -6 ≤ h ≤ 4, -16 ≤ k ≤ 19, -21 ≤ l ≤ 22 -11 ≤ h ≤ 11, -7 ≤ k ≤ 12, -14 ≤ l ≤ 10 Reflections collected 9243 3938 Independent reflections 2749 [Rint = 0.0314, Rsigma = 0.0255] 2172 [Rint = 0.0288, Rsigma = 0.0330] Data/restraints/parameters 2749/0/162 2172/0/132 Goodness-of-fit on F2 1.023 1.044 Final R indexes [I≥2σ (I)] R1 = 0.0351, wR2 = 0.0881 R1 = 0.0431, wR2 = 0.1146 Final R indexes [all data] R1 = 0.0387, wR2 = 0.0911 R1 = 0.0521, wR2 = 0.1219 Largest diff. peak/hole (e.Å-3) 0.19/-0.17 0.29/-0.25 Flack parameter 0.391(7) - CCDC 2203212 2203213 Table 2. Bond lengths and angles for HPAT and PIT. Compound Atom Atom Length (Å) Atom Atom Length (Å) HPAT S1 C2 1.749(3) C6 C7 1.504(5) S1 C7 1.823(4) C1' C2' 1.381(4) N3 C2 1.301(4) C1' C6' 1.373(5) N3 C4 1.468(4) C2' C3' 1.385(4) N8 C2 1.326(4) C3' C4' 1.366(5) N8 C1' 1.437(4) C4' C5' 1.373(5) C4 C5 1.508(4) C5' C6' 1.383(5) C5 C6 1.520(5) PIT S1 C2 1.7845(18) C6 C7 1.512(3) S1 C7 1.817(2) C1' C2' 1.393(2) N3 C2 1.357(2) C1' C6' 1.391(3) N3 C4 1.461(2) C2' C3' 1.380(3) N8 C2 1.283(2) C3' C4' 1.376(3) N8 C1' 1.412(2) C4' C5' 1.380(3) C4 C5 1.505(3) C5' C6' 1.378(3) C5 C6 1.508(3) Compound Atom Atom Atom Angle (°) Atom Atom Atom Angle (°) HPAT C2 S1 C7 103.31(16) C6 C7 S1 116.1(3) C2 N3 C4 125.9(3) C2' C1' N8 120.5(3) C2 N8 C1' 125.2(2) C6' C1' N8 118.7(3) N3 C2 S1 122.5(2) C6' C1' C2' 120.7(3) N3 C2 N8 122.7(3) C1' C2' C3' 119.0(3) N8 C2 S1 114.8(2) C4' C3' C2' 120.6(3) N3 C4 C5 115.1(3) C3' C4' C5' 120.0(3) C4 C5 C6 114.7(3) C4' C5' C6' 120.3(3) C7 C6 C5 114.0(3) C1' C6' C5' 119.4(3) PIT C2 S1 C7 103.79(10) C6 C7 S1 116.07(15) C2 N3 C4 123.75(17) C2' C1' N8 118.73(17) C2 N8 C1' 121.80(15) C6' C1' N8 123.08(16) N3 C2 S1 116.24(13) C6' C1' C2' 118.04(17) N8 C2 S1 123.03(14) C3' C2' C1' 120.69(18) N8 C2 N3 120.68(16) C4' C3' C2' 120.74(19) N3 C4 C5 115.07(18) C3' C4' C5' 118.96(19) C4 C5 C6 114.40(17) C6' C5' C4' 120.8(2) C5 C6 C7 114.35(18) C5' C6' C1' 120.68(18) The bond lengths of C2-N3 and C2-N8 were found as 1.301(4) and 1.326(4) Å, respectively (Table 2). The torsion angle of N3-C2-N9-C1′ is 14.58°. The seven-membered hetero- cycle has a chair conformation. PIT crystallizes in the monoclinic P21/n space group. Crystal data, data collection and structure refinement details are summarized in Table 1. The asymmetric unit contains one crystallographically independent molecule. The displacement ellipsoid plots and the numbering scheme for PIT molecule is provided in Figure 1. The bond lengths for the endocyclic and exocyclic C-N bonds found as 1.357(2) and 1.283(2) Å, respect- tively, indicate that in the crystal state the molecule was organized as an imine form (Table 2). The seven-membered heterocycle has a twist-chair conformation. In PIT molecule, S1, C2, N3, N8, and C1′ lay in the same plane with a RMS deviation of the fitted atoms of 0.023 Å and the dihedral angle between this plane and the benzene ring is 56.20(4)°. In the crystal, the intermolecular N-H···N hydrogen bonds link molecules to dimers (Figure 2). The geometry of the H-bonds is given in Table 3. 12 Umirov et al. / European Journal of Chemistry 14 (1) (2023) 9-15 2023 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.14.1.9-15.2345 Table 3. Parameters of hydrogen bonds in the crystal for HPAT (Å, °) *. D-H···A d(D-H) d(H···A) d(D···A) ∠ D-H···A N3-H3···Cl1 0.92(4) 2.26(4) 3.131(3) 159(3) N8-H···O1W 0.86 1.93 2.780(4) 168.00 O1W-H1W···Cl1i 0.98(6) 2.15(6) 3.122(4) 177(5) O1W-H2W···Cl1ii 0.91(5) 2.26(5) 3.163(4) 171(4) C2'-H2'A···Cl1iii 0.93 2.80 3.712(3) 167 * Symmetry codes: (i) 1-x, -1/2+y, 3/2-z; (ii) -x, -1/2+y, 3/2-z; (iii) 1+x, y, z. (a) (b) Figure 1. The molecular structure of HPAT (a) and PIT (b) with atom labelling. (a) (b) Figure 2. Intermolecular hydrogen bonding of molecules in the crystal of HPAT (a) and PIT (b). The packing analysis of HPAT shows that chlorine anions and water molecules form a zigzag-shaped H-bonded chain along the a-axis. Protonated thiazepine molecules links to this chain through N-H···O and N-H···Cl hydrogen bonds from differ- rent sides, resulting in H-bonded layers parallel to the ab plane (Figure 2). The geometry of the H-bonds is given in Table 3. 3.2. Hirshfeld surface analysis The Hirshfeld surface mapped in 3D dnorm [27-29] for studied compounds is given in Figure 3, where red spots represent short contacts. The longest contacts are represented by blue. The white color represents the contacts around the van der Waals radii [27,28]. The closest intermolecular interactions in the crystal of HPAT and PIT are N-H∙∙∙Cl/O and N-H∙∙∙N H- bonds, respectively. According to 3D Hirshfeld surface and 2D fingerprints [30] for HPAT were found the main contribution of close contacts H···H (59.6%), C···H/H···С (14.3%), S···H/H···S (9.5%), Cl···H/H···Cl (7.9%), O···H/H···O (5.0%) to intermolecular stabilization in the crystal. But the contributions of other contacts including N···H/H···N (1.2%) to the Hirshfeld surface are negligible (Figure 4). In the case of PIT, the contribution of H···H (64.7%) and C···H/H···С (19.6%) contacts are higher relatively to the contacts of HPAT. In addition, N···H (8.0%) and S···H (7.4%) contacts make a significant contribution to close contacts of PIT (Figure 5). Umirov et al. / European Journal of Chemistry 14 (1) (2023) 9-15 13 2023 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.14.1.9-15.2345 (a) (b) Figure 3. Hirshfeld surfaces of HPAT (a) and PIT (b) mapped with dnorm. Figure 4. The 2D fingerprint plots of the HPAT. Figure 5. The 2D fingerprint plots of the PIT. 14 Umirov et al. / European Journal of Chemistry 14 (1) (2023) 9-15 2023 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.14.1.9-15.2345 4. Conclusions For the first time, 2-phenylaminotetrahydro-1,3-thiazepine hydrochloride has been obtained by cyclization of 1-(4-hydroxy butyl)-3-phenylthiourea in an acidic medium and it’s structure was elucidated trough single crystal X-ray analysis. The crystal unit cell of HPAT contains four molecules of protonated (on N3 atom) amine tautomer, four chlorine anion, and four water molecules. Chlorine anion and water molecules play the role of a bridge connecting protonated amine molecules through the H-bond with hydrogen atoms of N3 and N8 nitrogen atoms. Neutralization efforts of the hydrochloride of the amine tautomer by sodium bicarbonate to obtain a neutral amine tautomer led to the formation of an imine tautomer. The structure of the imine form was also elucidated by X-ray analysis and it was found that in the crystal, pairs of 2-phenyl iminohexahydro-1,3-thiazepine are linked via N-H∙∙∙N hydro- gen bonds, forming centrosymmetric dimers. The type and main contribution of intermolecular interactions are visualized through Hirshfeld surface analysis and 2D fingerprint plots. Supporting information The CCDC-2203212 and 2203213 contain the supplementary crystallo- graphic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by e-mailing data_request@ ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033. Disclosure statement Conflict of interest: The authors declare that they have no conflict of interest. Ethical approval: All ethical guidelines have been adhered. Sample availability: Sample of the compounds are available from the author. CRediT authorship contribution statement Conceptualization: Alisher Eshimbetov, Khamid Khodjaniyazov; Methodology: Mukhriddin Umirov, Alisher Eshimbetov; Software: Jamshid Ashurov; Kambarali Turgunov; Validation: Alisher Eshimbetov; Formal Analysis: Alisher Eshimbetov; Investigation: Mukhriddin Umirov, Alisher Eshimbetov; Resources: Mukhriddin Umirov; Data Curation: Mukhriddin Umirov; Alisher Eshimbetov; Writing - Original Draft: Mukhriddin Umirov, Alisher Eshimbetov, Kambarali Turgunov; Writing - Review and Editing: Alisher Eshimbetov, Jamshid Ashurov, Khamid Khodjaniyazov; Visualization: Jamshid Ashurov, Kambarali Turgunov; Funding acquisition: Mukhriddin Umirov; Supervision: Alisher Eshimbetov; Project Administration: Jamshid Ashurov. ORCID and Email Mukhriddin Umirov chemnatproduct.nuuz@gmail.com https://orcid.org/0000-0001-9424-5540 Alisher Eshimbetov ealisherg@yahoo.com https://orcid.org/0000-0002-9447-9133 Jamshid Ashurov atom.uz@mail.ru https://orcid.org/0000-0002-4441-2803 Kambarali Turgunov kk_turgunov@rambler.ru https://orcid.org/0000-0001-5741-6347 Khamid Khodjaniyazov hamidkhodjaniyazov@yandex.ru https://orcid.org/0000-0001-7688-2474 References [1]. Remko, M.; Walsh, O. A.; Richards, W. G. Ab initio and DFT study of molecular structure and tautomerism of 2-amino-2-imidazoline, 2- amino-2-oxazoline and 2-amino-2-thiazoline. Chem. Phys. Lett. 2001, 336, 156–162. [2]. Shishkin, O. V.; Konovalova, I. S.; Zubatyuk, R. I.; Palamarchuk, G. V.; Shishkina, S. V.; Biitseva, A. V.; Rudenko, I. V.; Tkachuk, V. A.; Kornilov, M. Y.; Hordiyenko, O. V.; Leszczynski, J. Remarkably strong polarization of amidine fragment in the crystals of 1-imino-1H- isoindol-3-amine. Struct. Chem. 2013, 24, 1089–1097. [3]. Aly, A. 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This is an open access article distributed under the terms and conditions of the CC BY NC License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited without any further permission from Atlanta Publishing House LLC (European Journal of Chemistry). No use, distribution, or reproduction is permitted which does not comply with these terms. Permissions for commercial use of this work beyond the scope of the License (http://www.eurjchem.com/index.php/eurjchem/pages/view/terms) are administered by Atlanta Publishing House LLC (European Journal of Chemistry). http://www.eurjchem.com/index.php/eurjchem/pages/view/terms http://creativecommons.org/licenses/by-nc/4.0 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms 1. Introduction 2. Experimental 2.1. Synthesis of hydrogenated 1,3-thiazepines 2.1.1. 1-(4-Hydroxybutyl)-3-phenylthiourea 2.1.2. Hydrochloride of 2-phenylaminotetrahydro-1,3-thiazepine (HPAT) 2.1.3. 2-Phenyliminohexahydro-1,3-thiazepine (PIT) 2.2. Single crystal X‐ray diffraction analysis 2.3. Theoretical studies 3. Results and discussion 3.1. Single crystal X‐ray diffraction analysis 3.2. Hirshfeld surface analysis 4. Conclusions Supporting information Disclosure statement CRediT authorship contribution statement ORCID and Email References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField15: PrintField16: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: PrintField25: PrintField26: