2-[(1E)-[(Z)-2-({[(1Z)-[(E)-2-[(2-Hydroxyphenyl)methylidene]hydrazin-1-ylidene]({[(4-methylphenyl)methyl]sulfanyl})methyl]disulfanyl}({[(4-methylphenyl)methyl]sulfanyl})methylidene)hydrazin-1-ylidene]methyl]phenol: crystal structure, Hirshfeld surface analysis and computational study

The title hydrazine carbodithioate derivative is highly twisted as seen in the C—S—S—C torsion angle of 90.70 (8)°; the molecule is twofold symmetric. In the molecular packing, molecules are assembled into supramolecular layers in the ab plane by methylene-C—H⋯π(tolyl) interactions.

The complete molecule of the title hydrazine carbodithioate derivative, C 32 H 30 N 4 O 2 S 4 , is generated by a crystallographic twofold axis that bisects the disulfide bond. The molecule is twisted about this bond with the C-S-S-C torsion angle of 90.70 (8) indicating an orthogonal relationship between the symmetry-related halves of the molecule. The conformation about the imine bond [1.282 (2) Å ] is E and there is limited delocalization of -electron density over the CN 2 C residue as there is a twist about the N-N bond [C-N-N-C torsion angle = À166.57 (15) ]. An intramolecular hydroxyl-O-HÁ Á ÁN(imine) hydrogen bond closes an S(6) loop. In the crystal, methylene-C-HÁ Á Á(tolyl) contacts assemble molecules into a supramolecular layer propagating in the ab plane: the layers stack without directional interactions between them. The analysis of the calculated Hirshfeld surfaces confirm the importance of HÁ Á ÁH contacts, which contribute 46.7% of all contacts followed by HÁ Á ÁC/CÁ Á ÁH contacts [25.5%] reflecting, in part, the C-HÁ Á Á(tolyl) contacts. The calculation of the interaction energies confirm the importance of the dispersion term and the influence of the stabilizing HÁ Á ÁH contacts in the inter-layer region.

Chemical context
Schiff base molecules can be derived from the condensation of S-alkyl-dithiocarbazate derivatives with heterocyclic aldehydes and ketones to form molecules of the general formula RSC( S)N(H)N C(R 0 )R 00 , where R 0 , R 00 = alkyl and aryl. These molecules are effective ligands for a variety of metals and the motivation for complexation largely stems from the promising biological activity exhibited by the derived metal complexes (Low et al., 2016;Ravoof et al., 2017;Yusof et al., 2020). However, these Schiff bases are susceptible to oxidation resulting in the formation of a disulfide bond, as has been observed previously (Amirnasr et al., 2014;Sohtun et al., 2018). This is the case in the present report where the title compound, (I), was the side-product from the synthesis of the Schiff base, 4-methylbenzyl-2-(2-hydroxybenzylidene) hydrazinecarbodithioate (Ravoof et al., 2010). After crystals of the desired Schiff base that had precipitated overnight were removed by filtration, the slow evaporation of the filtrate over a period of several days yielded crystals of (I). Herein, the ISSN 2056-9890 crystal and molecular structures of (I) are described along with an analysis of the calculated Hirshfeld surfaces and computation of interaction energies in the crystal.

Structural commentary
The crystallographic asymmetric unit of (I) comprises half a molecule as it is disposed about a twofold axis of symmetry bisecting the disulfide bond, Fig. 1. The C1, N1, S1 and S2 atoms lie in a plane with an r.m.s. deviation of 0.0020 Å . The appended N2 and C5 atoms lie 0.036 (2) and 0.052 (2) Å to one side of the plane and the S1 i atom À0.1659 (16) Å to the other side; symmetry operation (i): 1 À x, y, 3 2 À z. The C1-S1 bond length of 1.7921 (17) Å is significantly longer than the C1-S2 bond of 1.7463 (17) Å , which is ascribed to the S1 atom participating in the S1-S1 i bond of 2.0439 (8) Å ; each C1-S bond is shorter than the C9-S2 bond length of 1.8308 (18) Å .
The sequence of C1 N1 (E-conformation), N1-N2 and C2 N2 bond lengths is 1.282 (2), 1.409 (2) and 1.286 (2) Å , respectively, and suggests limited delocalization of -electron density over this residue which is consistent with a twist about the N1-N2 bond as seen in the C1-N1-N2-C2 torsion angle of À166.57 (15) . The presence of an intramolecular hydroxyl-O-HÁ Á ÁN(imine) hydrogen bond, Table 1, is noted and accounts for the planarity in this region of the molecule as seen in the values of the N2-C2-C3-C4 and C2-C3-C4-O1 torsion angles of 3.8 (3) and 1.8 (3) , respectively. The dihedral angle between the hydroxybenzene and tolyl rings is 65.11 (6) , indicating a significant twist in this part of the molecule. Overall, the molecule is twisted about the central disulfide bond with the C1-S1-S1 i -C1 i torsion angle being 90.70 (8) and the dihedral angle between the two CNS 2 planes being 88.22 (3) .

Supramolecular features
In the crystal, the only directional contact identified in the geometric analysis of the molecular packing employing The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level.  Table 1 Hydrogen-bond geometry (Å , ).
Cg1 is the centroid of the (C10-C15) ring. PLATON (Spek, 2020), is a methylene-C-HÁ Á Á(tolyl) contact, Table 1. As each molecule donates and accepts two such contacts and these extend laterally, a supramolecular layer in the ab plane is formed, Fig. 2(a). Layers stack along the c axis without directional interactions between them, Fig. 2

Analysis of the Hirshfeld surfaces
The Hirshfeld surface analysis comprising d norm surface, electrostatic potential (calculated using wave function at the HF/STO-3 G level of theory) and two-dimensional fingerprint plot calculations were performed for (I) to quantify the interatomic interactions between molecules. This was accomplished using Crystal Explorer 17 (Turner et al., 2017) and following established procedures (Tan et al., 2019). The brightred spots on the Hirshfeld surface mapped over d norm in Fig. 3(a), i.e. near the imine-C2 and tolyl ring, centroid designated Cg1, correspond to the C2Á Á ÁO1, C2Á Á ÁC4 short contacts (with separations $0.15 Å shorter than the sum of their van der Waals radii, Table 2) and the methylene-C9-H9AÁ Á Á(tolyl) interaction, Table 1. In addition, this methylene-C9-H9AÁ Á Á(tolyl) interaction shows up as a distinctive orange 'pothole' on the shape-index-mapped Hirshfeld surface, Fig. 3 In the views of Fig. 4(a), the faint red spots appearing near the tolyl-H12, methylene-H9B and phenol-H8 atoms correlate with the faint red spots near the sulfanyl-S1, hydrazine-N1 and tolyl-C11 atoms, and correspond to the intra-layer tolyl-C12-H12Á Á ÁS1(sulfanyl), methylene-C9-H9BÁ Á ÁN1(hydrazine) and phenol-C8-H8Á Á ÁC11(tolyl) interactions, Table 2. These interactions are also reflected in the Hirshfeld surface mapped over the calculated electrostatic potential in Fig. 4(b), with the blue and red regions corresponding to positive and negative electrostatic potentials, respectively.
The corresponding two-dimensional fingerprint plots for the calculated Hirshfeld surface of (I) are shown with characteristic pseudo-symmetric wings in the upper left and lower right sides of the d e and d i diagonal axes for the overall fingerprint plot, Fig. 5(a); those delineated into HÁ Á ÁH, HÁ Á ÁC/ CÁ Á ÁH, HÁ Á ÁS/SÁ Á ÁH, HÁ Á ÁO/OÁ Á ÁH, NÁ Á ÁC/CÁ Á ÁN and HÁ Á ÁN/ NÁ Á ÁH contacts are illustrated in Fig. 5(b)-(g), respectively. The percentage contributions for the different interatomic contacts to the Hirshfeld surface are summarized in Table 3. The greatest contribution to the overall Hirshfeld surface is due to HÁ Á ÁH contacts, which contribute 43.9% and features a round-shaped peak tipped at d e = d i $2.4 Å , Fig. 5(b). The tip of this HÁ Á ÁH contact corresponds to an inter-layer H6Á Á ÁH14 contact with a distance of 2.39 Å , Table 2; the remaining HÁ Á ÁH contacts are either around or longer than the sum of their van der Waals radii. The HÁ Á ÁC/CÁ Á ÁH contacts contribute 25.5% to the overall Hirshfeld surface, reflecting, in part, Views of the Hirshfeld surface for (I) mapped over (a) d norm in the range À0.104 to + 1.517 arbitrary units and (b) the shape-index property.

Table 2
A summary of short interatomic contacts (Å ) for (I) a .

Contact
Distance Symmetry operation The interatomic distances are calculated in Crystal Explorer 17 (Turner et al., 2017) with the X-H bond lengths adjusted to their neutron values.

Figure 4
Views of the Hirshfeld surface mapped for (I) over (a) d norm in the range À0.104 to + 1.517 arbitrary units and (b) the calculated electrostatic potential in the range À0.056 to 0.031 a.u. The red and blue regions represent negative and positive electrostatic potentials, respectively.  (g), their contributions to the overall Hirshfeld surface are only 3.6 and 3.4%, respectively. The contributions from the other interatomic contacts summarized in Table 3 have an insignificant influence on the calculated Hirshfeld surface of (I).

Computational chemistry
In the present analysis, the pairwise interaction energies between the molecules in the crystal of (I) were calculated by employing the 6-31G(d,p) basis set with the B3LYP function.    A summary of interaction energies (kJ mol À1 ) calculated for (I).
repulsion (E rep ) energies and these were calculated in Crystal Explorer 17 (Turner et al., 2017). The characteristics of the calculated intermolecular interaction energies are summarized in Table 4. As postulated, in the absence of conventional hydrogen bonding in the crystal, the E dis energy term makes the major contribution to the interaction energies. The greatest stabilization energy (-65.7 kJ mol À1 ) occurs within the intra-layer region and arises from the combination of C-HÁ Á Á, CÁ Á ÁO and CÁ Á ÁC short contacts as well as weak C-HÁ Á ÁN/C interactions. The second most significant energy of stabilization within the intra-layer region involves a major contribution from the tolyl-C12-H12Á Á ÁS1(sulfanyl) interaction (dominated by E dis ) with a total energy of À29.7 kJ mol À1 . In addition, a long-range H6Á Á ÁH16B contact is observed within the intra-layer region with a HÁ Á ÁH separation of 2.44 Å . The E dis energy term also makes the major contribution to the energies of stabilization in the inter-layer region, with the separation between molecules in the inter-layer region being HÁ Á ÁH contacts. The maximum energy is not found for the shortest H6Á Á ÁH14 contact (-9.5 kJ mol À1 ), Table 2, but rather a pair of phenol-H5Á Á ÁH14(tolyl) contacts (-24.6 kJ mol À1 ), each with a distance of 2.51 Å . Views of the energy framework diagrams down the b axis are shown in Fig. 6 and emphasize the importance of E dis in the stabilization of the crystal.

Database survey
In the crystallographic literature, there are four precedents for (I) with details collated in Table 5

Synthesis and crystallization
Crystals of (I) were isolated from an ethanol-acetonitrile solution by slow evaporation and was a side-product from the synthesis of the Schiff base 4-methylbenzyl-2-(2-hydroxybenzylidene) hydrazinecarbodithioate carried out by heating a mixture of S-4-methylbenzyldithiocarbazate (10 mmol) and salicylaldehyde (10 mmol) in $30 ml of acetonitrile for about 2 h (Ravoof et al., 2010). Slow evaporation of the remaining filtrate after removal of the desired product over a period of several days gave yellow plates of (I).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 6. The carbon-bound H atoms were placed in calculated positions (C-H = 0.95-0.99 Å ) and were included in the refinement in the riding-model approximation, with U iso (H) set to 1.2U eq (C). The O-bound H atom was located in a difference-Fourier map, but was refined with an O-H = 0.84AE0.01 Å distance restraint, and with U iso (H) set to 1.5U eq (O).
Acta Cryst. (2020). E76, 1245-1250 research communications Table 6 Experimental details.  DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.45 e Å −3 Δρ min = −0.20 e Å −3 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.