Crystal structure of 1-(4-methyl­phen­yl)-3-(propan-2-yl­­idene­amino)­thio­urea

In the title thio­semicarbazone, C₁₁H₁₅N₃S, the p-tolyl-N—H and imino-N—H groups are anti and syn, respectively, to the central thione-S atom. This allows for the formation of an intra­molecular p-tolyl-N—H⋯N(imino) hydrogen bond. The mol­ecule is twisted with the dihedral angle between the p-tolyl ring and the non-hydrogen atoms of the N=CMe₂ residue being 29.27 (8)°. The crystal packing features supra­molecular layers lying in the bc plane whereby centrosymmetric aggregates sustained by eight-membered thio­amide {⋯HNCS}₂ synthons are linked by further N—H⋯S hydrogen bonds. Layers are connected via methyl-C—H⋯π inter­actions. The supra­molecular aggregation was further investigated by an analysis of the Hirshfeld surface and comparison made to related structures.

1. Chemical context

The reaction between an alcohol or amine (primary or secondary) with N-alkyl- or N-aryl-iso­thio­cyanides usually results in the formation of thio­carbamides. For example, in the case of reactions involving a monofunctional alcohol, the reaction proceeds in the following manner: R—OH + R′N=C=S → ROC(=S)N(H)R′ (Ho et al., 2005). Often, reactions are facilitated by initially employing an alkali metal hydroxide as the base and later adding an acid, e.g. HCl (Ho et al., 2005). Such mol­ecules are of inter­est as when deprotonated, they can function as effective thiol­ate ligands for phosphanegold(I) derivatives, which display biological activity. For example, Ph₃PAu[SC(O–alk­yl)=N(ar­yl)] com­pounds exhibit significant cytotoxicity against a variety of cancer cell lines and mechanistic studies show that they can kill cancer cells by initiating a variety of apoptotic pathways, both extrinsic and intrinsic (Yeo, Ooi et al., 2013; Ooi, Yeo et al., 2015). Related species, i.e. Ph₃PAu[SC(O–alk­yl)=N(p-tol­yl)], exhibit potency against Gram-positive bacteria (Yeo, Sim et al., 2013). Over and above these considerations, systematic studies into the structural chemistry of these mol­ecules, which have proven relatively easy to crystallize, have been of some inter­est in crystal engineering endeavours (Ho et al., 2006; Kuan et al., 2008). In the course of studies to increase the functionality of the thio­carbamide mol­ecules, bipodal {1,4-[MeOC(=S)N(H)]₂C₆H₄} was successfully synthesized along with binuclear phosphanegold(I) complexes (Yeo, Khoo et al., 2015). Recent attempts at expanding this chemistry by using thio­urea as an amine donor have been undertaken. As reported very recently, 1:2 reactions between thio­urea and R′N=C=S resulted in the isolation of salts containing 1,2,3-thia­zole-based cations resulting from 1:1 cyclizations (Yeo, Tan et al., 2015). Herein, the product of an analogous reaction involving a bifunctional amine, i.e. H₂NNH₂ (hydrazine) with (p-tol­yl)N=C=S, conducted in acetone solution, is described, namely the thio­semicarbazone, (I). Mol­ecules related to (I) and especially their metal complexes continue to attract attention owing to potential biological activity (Dilworth & Hueting, 2012; Lukmantara et al., 2013; Su et al., 2013).

1.1. Structural commentary

The mol­ecular structure of (I), Fig. 1, comprises three planar regions. The central NC(=S)N chromophore (the r.m.s. deviation of the fitted atoms is 0.0020 Å) has anti- and syn-dispositions of the N1- and N2-bound H atoms, respectively, with respect to the central thione-S1 atom. The N1-bound H atom is syn to the imino-N3 atom allowing for the formation of a five-membered loop via an N1—H⋯N3 hydrogen bond, Table 1. The central plane forms dihedral angles of 23.49 (4)° with the propan-2-yl­idene­amino residue (N=CMe₂; r.m.s. deviation for the C₃N atoms = 0.0002 Å) and 43.30 (5)° with the p-tolyl ring. Overall, the mol­ecule is twisted as qu­anti­fied by the dihedral angle between the outer planes of 29.27 (8)°.

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯N3	0.88 (1)	2.09 (2)	2.572 (2)	114 (1)
N1—H1N⋯S1^i	0.88 (1)	2.87 (2)	3.5618 (17)	137 (2)
N2—H2N⋯S1^ii	0.88 (2)	2.57 (2)	3.4373 (16)	169 (2)
C8—H8C⋯Cg1^iii	0.98	2.81	3.716 (2)	154
Symmetry codes: (i) ; (ii) -x, -y, -z+1; (iii) -x+1, -y, -z+1.

Figure 1 The mol­ecular structure of (I) showing displacement ellipsoids at the 70% probability level.

Two P2₁/c polymorphs have been reported for the parent compound, i.e. having a phenyl rather than a p-tolyl substit­uent (Jian et al., 2005; Venkatraman et al., 2005); the structure of (I) also crystallizes in the P2₁/c space group. As revealed from the data collated in Table 2, there is a high degree of concordance in the key bond lengths and angles for the three mol­ecules, as might be expected. However, there are some notable differences in the torsion-angle data as well as in the dihedral angles between the three least-squares planes discussed above, Table 2. From these and the overlay diagram shown in Fig. 2, it is apparent that the mol­ecular structure of (I) more closely matches that observed in the polymorph reported by Venkatraman et al. (2005) rather than that described by Jian et al. (2005). This conclusion is also vindicated in the unit cell data, i.e. a = 12.225 (3), b = 7.618 (2), c = 11.639 (3) Å, β = 102.660 (4)° reported for the former (Venkatraman et al., 2005).

Table 2
Geometric data (Å, °) for (I) and two polymorphs of (II)

Parameter	(I)	Form a of (II)^a	Form b of (II)^b
N2—N3	1.397 (2)	1.386 (2)	1.392 (2)
C1—S1	1.6873 (18)	1.6816 (17)	1.6826 (17)
C1—N1	1.350 (2)	1.337 (2)	1.343 (2)
C1—N2	1.350 (2)	1.359 (2)	1.348 (2)
C2—N1	1.422 (2)	1.420 (2)	1.425 (2)
C9—N3	1.280 (2)	1.279 (2)	1.276 (2)
C1—N1—C2	127.79 (16)	129.98 (14)	127.97 (14)
C1—N2—N3	117.72 (15)	118.17 (14)	118.33 (14)
N2—N3—C9	117.91 (15)	118.85 (15)	117.73 (14)
S1—C1—N1	125.45 (14)	126.00 (13)	125.75 (13)
S1—C1—N2	120.00 (14)	119.37 (13)	119.50 (12)
N1—C1—N2	114.54 (16)	114.63 (15)	114.74 (15)
S1—C1—N2—N3	−169.57 (12)	177.46 (12)	−170.56 (12)
C1—N1—C2—C3	132.2 (2)	−153.87 (18)	131.10 (19)
C1—N2—N3—C9	−165.78 (16)	168.43 (16)	−165.85 (15)
CN2S / C3N	23.49 (4)	13.19 (8)	22.42 (9)
CN2S / ar­yl	43.30 (5)	39.26 (6)	43.90 (6)
C3N / ar­yl	29.27 (8)	40.15 (8)	30.18 (8)
Notes: (a) Jian et al. (2005); (b) Venkatraman et al. (2005).

Figure 2 Overlay diagram of the mol­ecules in (I), red image, and (II), forms a (green) and b (blue). The mol­ecules have been overlapped so that the central NC(=S)N chromophores are coincident.

2. NMR invesitgations

The conformation of (I) was also investigated in CDCl₃ solution by NMR methods. Assignments were made with the aid of the inter­pretative program, Chemdraw Ultra (CambridgeSoft Corporation, 2002). On the basis of multiple ¹H and ¹³C{¹H} resonances for the methyl groups of the propan-2-yl­idene­amino residue, it appears that the (propan-2-yl­idene­amino)­thio­urea residue has a locked configuration, consistent with the persistence of the intra­molecular N1—H⋯N3 hydrogen bond in CDCl₃ solution.

3. Supra­molecular features

In the crystal, N—H⋯S and C—H⋯π inter­actions provide identifiable points of contact between mol­ecules; these inter­actions are qu­anti­fied in Table 1. Centrosymmetrically related mol­ecules are connected by pairs of amide-N2—H⋯S1 hydrogen bonds, forming eight-membered thio­amide {⋯HNCS}₂ synthons. These are connected into supra­molecular layers in the bc plane by amide-N1—H⋯S1 hydrogen bonds so that the S1 atom accepts two hydrogen bonds, Fig. 3. The p-tolyl groups protrude to either side of each layer and inter-digitate along the a axis with adjacent layers allowing for the formation of methyl-C8—H⋯π(C2–C7) inter­actions, thereby consolidating the three-dimensional architecture, Fig. 4.

Figure 3 Supra­molecular layer in the bc plane in the crystal packing of (I). Centrosymmetric aggregates mediated by eight-membered thio­amide {⋯HNCS}2 synthons (shown as orange dashed lines) are linked by additional amide-N—H⋯S hydrogen bonds, shown as blue dashed lines.

Figure 4 A view of the unit cell contents of (I) shown in projection down the b axis. Supra­molecular layers, illustrated in Fig. 3, are linked via C—H⋯π inter­actions, shown as purple dashed lines, leading to a three-dimensional architecture.

4. Analysis of the Hirshfeld surfaces

The crystal packing was further investigated by an analysis of the Hirshfeld surface (Spackman & Jayatilaka, 2009) employing CrystalExplorer (Wolff et al., 2012). Fingerprint plots (Rohl et al., 2008) were calculated, as were the electrostatic potentials using TONTO (Spackman et al., 2008; Jayatilaka et al., 2005) integrated into CrystalExplorer; the electrostatic potentials were mapped on the Hirshfeld surfaces using the STO–3G basis set at the level of Hartree–Fock theory over a range of ±0.075 au.

Two views of the Hirshfeld surface mapped over d_norm are shown in Fig. 5a and b. The deep-red depressions at the S1 and N2 atoms (Fig. 5a) confirm their role as an acceptor and donor in the hydrogen-bonding scheme, respectively. This is also evident from the dark-red and blue regions, respectively, on the Hirshfeld surface mapped over the calculated electrostatic potential (Fig. 5c). The diminutive red spots near S1 and N1 (Fig. 5b) indicate their involvement in the inter­molecular N—H⋯S hydrogen bond.

Figure 5 Views of the Hirshfeld surface for (I): (a) and (b) mapped over dnorm, and (c) mapped over the calculated electrostatic potential.

The overall two-dimensional fingerprint plot (Fig. 6a) and those delineated into H⋯H, S⋯H/H⋯S, N⋯H/H⋯N and C⋯H/H⋯C H⋯H (Fig. 6b–d, respectively) inter­actions operating in the crystal structure of (I) are illustrated in Fig. 6; the relative contributions are summarized in Table 3. The prominent pair of sharp spikes of equal length (d_e + d_i = 2.45 Å; Fig. 6b) with a 15.2% contribution due to S⋯H/H⋯S contacts to the Hirshfeld surfaces also suggest the presence of these inter­actions in the crystal packing. The light-red region near N3 (Fig. 5a) and diminutive red spot near N1—H (Fig. 5b) are consistent with relatively smaller contributions from N⋯H/H⋯N contacts, i.e. 2.5 and 3.0%, respectively, and are indicative of the weak intra­molecular hydrogen bond. The strength of such an inter­action can be visualized from the 2D fingerprint plot corresponding to N⋯H/ H⋯N contacts (Fig. 6c). The bright-orange spot in the surface mapped with d_e (within a red circle in Fig. 7) about the aryl ring and a light-blue region around the tolyl-hydrogen atom, H8C (Fig. 7), suggest a contribution from the C—H⋯π inter­action (Table 1). This is also evident through distinct pair of `wings' in the fingerprint plot corresponding to C⋯H/H⋯C contacts (Fig. 6d). The wing at the top, left belongs to C—H donors, while that at the bottom, right corresponds to the surface around π-acceptors with 11.3 and 7.8% contribution from C⋯H and H⋯C contacts, respectively. The H⋯H contacts reflected in the middle of scattered points in Fig. 6e provide the most significant contribution, i.e. 57.0%, to the Hirshfeld surface arising from a side-ways approach. The small, flat segments delineated by the blue outline in the surface mapped with curvedness (Fig. 8) and the small (i.e. 0.7%) contribution from C⋯C contacts to the surface indicates the absence of π–π stacking inter­actions in the structure.

Table 3
Relative contribution (%) to inter­molecular inter­actions calculated from the Hirshfeld surface

Contact	Contribution
H⋯H	57.0
S⋯H/H⋯S	15.2
N⋯H/H⋯N	5.5
C⋯H/H⋯C	19.1
C⋯C	0.7
N⋯N	1.4
C⋯N	0.8
C⋯S	0.2
others	0.1

Figure 6 2D Fingerprint plots for (I): (a) full, (b) delineated to show S⋯H/H⋯S, (c) N⋯H/H⋯N, (d) C⋯H/H⋯C, and (e) H⋯H inter­actions.

Figure 7 View of the Hirshfeld surface for (I) mapped over de.

Figure 8 Hirshfeld surfaces for (I) mapped over curvedness.

5. Database survey

According to a search of the Cambridge Structural Database (Groom & Allen, 2014), there are no direct analogues of (I), either in the coordinated or uncoordinated form. As mentioned in the Structural commentary, the parent compound has been characterized in two polymorphic forms (Jian et al., 2005; Venkatraman et al., 2005). The parent compound, LH, has also been observed to coordinate metal centres. Thus, monodentate coordination via the thione-S atom was observed in a neutral complex [ZnCl₂(LH)₂] (Bel'skii et al., 1987). By contrast, a chelating mode via thione-S and imino-N atoms was observed in each of the charged complexes [CoBr(LH)₂]Br (Dessy et al., 1978) and [(η⁶-p-cymene)RuCl(LH)]Cl (Su et al., 2013). The most closely related structure having the p-tolyl substituent but variations at the imino-N atom is one where one methyl group has been substituted by a phenyl (Zhang et al., 2011). This is also a twisted mol­ecule with the dihedral angle between the p-tolyl and NC₃ residues being 65.44 (7)°.

6. Synthesis and crystallization

To p-tolyl iso­thio­cyanate (Sigma–Aldrich; 10 mmol, 1.49 g) in acetone (20 ml) was added hydrazine monohydrate (Sigma–Aldrich; 10 mmol, 0.76 ml). The resulting mixture was stirred for 4 h at room temperature. Both chloro­form (20 ml) and aceto­nitrile (20 ml) were then added, and the resulting mixture left for slow evaporation. Light-brown crystals were obtained after 2 weeks. Yield: 2.012 g (91%). M.p. 412–413 K. ¹H NMR (400 MHz, CDCl₃, 298 K): 9.19 (s, br, 1H, NH—N), 8.56 (s, br, 1H, NH), 7.49 (d, 2H, m-aryl, J = 8.28 Hz), 7.17 (d, 2H, o-aryl, J = 8.24 Hz), 2.34 (s, 3H, aryl-CH₃), 2.05 (s, 3H, CH₃), 1.94 (s, 3H, CH₃). ¹³C NMR (400 MHz, CDCl₃, 298 K): 176.4 [CS], 149.6 [C(CH₃)₂], 135.8 [C_ipso], 135.4 [C_para], 129.3 [C_meta], 124.5 [C_ortho], 25.3 [CH₃], 21.0 [aryl-CH₃], 16.9 [CH₃, syn to N—H]. IR (cm⁻¹): ν(N—H) 3240, 3168 (m), ν(C=N) 1514 (vs), ν(C—N) 1267 (s), ν(C=S) 1188 (vs).

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4. Carbon-bound H-atoms were placed in calculated positions (C—H = 0.95–0.98 Å) and were included in the refinement in the riding model approximation, with U_iso(H) set to 1.2–1.5U_eq(C). The N-bound H atoms were located in a difference Fourier map but were refined with a distance restraint of N—H = 0.88±0.01 Å, and with U_iso(H) set to 1.2U_eq(N).

Table 4
Experimental details

Crystal data
Chemical formula	C11H15N3S
Mr	221.32
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	100
a, b, c (Å)	13.7289 (13), 7.4341 (7), 11.5757 (11)
β (°)	102.690 (1)
V (Å^3)	1152.58 (19)
Z	4
Radiation type	Mo Kα
μ (mm^−1)	0.25
Crystal size (mm)	0.12 × 0.05 × 0.03
Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
Tmin, Tmax	0.970, 0.993
No. of measured, independent and observed [I > 2σ(I)] reflections	10739, 2646, 2052
Rint	0.050
(sin θ/λ)max (Å^−1)	0.650
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.041, 0.098, 1.02
No. of reflections	2646
No. of parameters	147
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å^−3)	0.27, −0.27
Computer programs: APEX2 and SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL2014/7 (Sheldrick, 2015), ORTEP-3 for Windows (Farrugia, 2012), QMol (Gans & Shalloway, 2001), DIAMOND (Brandenburg, 2006) and publCIF (Westrip, 2010).

Supporting information

S1. Chemical context

The reaction between an alcohol or amine (primary or secondary) with N-alkyl- or N-aryl-iso­thio­cyanides usually results in the formation of thio­carbamides. For example, in the case of reactions involving a monofunctional alcohol, the reaction proceeds in the following manner: R—OH + R'N═C═S → ROC(═ S)N(H)R' (Ho et al., 2005). Often, reactions are facilitated by initially employing an alkali metal hydroxide as the base and later adding an acid, e.g. HCl (Ho et al., 2005). Such molecules are of inter­est as when deprotonated, they can function as effective thiol­ate ligands for phosphanegold(I) derivatives, which display biological activity. For example, Ph₃PAu[SC(O–alkyl)═N(aryl)] compounds exhibit significant cytotoxicity against a variety of cancer cell lines and mechanistic studies show that they can kill cancer cells by initiating a variety of apoptotic pathways, both extrinsic and intrinsic (Yeo, Ooi et al., 2013; Ooi, Yeo et al., 2015). Related species, i.e. Ph₃PAu[SC(O–alkyl)═ N(p-tolyl)], exhibit potency against Gram-positive bacteria (Yeo, Sim et al., 2013). Over and above these considerations, systematic studies into the structural chemistry of these molecules, which have proven relatively easy to crystallize, have been of some inter­est in crystal engineering endeavours (Ho et al., 2006; Kuan et al., 2008). In the course of studies to increase the functionality of the thio­carbamide molecules, bipodal {1,4-[MeOC(═S)N(H)]₂C₆H₄} was successfully synthesized along with binuclear phosphanegold(I) complexes (Yeo, Khoo et al., 2015). Recent attempts at expanding this chemistry by using thio­urea as an amine donor have been undertaken. As reported very recently, 1:2 reactions between thio­urea and R'N═C═S resulted in the isolation of salts containing 1,2,3-thia­zole-based cations resulting from 1:1 cyclizations (Yeo, Tan et al., 2015). Herein, the product of an analogous reaction involving a bifunctional amine, i.e. H₂NNH₂ (hydrazine) with (p-tolyl)N═C═S, conducted in acetone solution, is described, namely the thio­semicarbazone, (I). Molecules related to (I) and especially their metal complexes continue to attract attention owing to potential biological activity (Dilworth & Hueting, 2012; Lukmantara et al., 2013; Su et al., 2013).

S1.1. Structural commentary

The molecular structure of (I), Fig. 1, comprises three planar regions. The central NC(═S)N chromophore (the r.m.s. deviation of the fitted atoms is 0.0020 Å) has anti- and syn-dispositions of the N1- and N2-bound H atoms, respectively, with respect to the central thione-S1 atom. The N1-bound H atom is syn to the imino-N3 atom allowing for the formation of a five-membered loop via an N1—H···N3 hydrogen bond, Table 1. The central plane forms dihedral angles of 23.49 (4)° with the propan-2-yl­idene­amino residue (N═CMe₂; r.m.s. deviation for the C₃N atoms = 0.0002 Å) and 43.30 (5)° with the p-tolyl ring. Overall, the molecule is twisted as qu­anti­fied by the dihedral angle between the outer planes of 29.27 (8)°.

Two P2₁/c polymorphs have been reported for the parent compound, i.e. having a phenyl rather than a p-tolyl substituent (Jian et al., 2005; Venkatraman et al., 2005); the structure of (I) also crystallizes in the P2₁/c space group. As revealed from the data collated in Table 2, there is a high degree of concordance in the key bond lengths and angles for the three molecules, as might be expected. However, there are some notable differences in the torsion-angle data as well as in the dihedral angles between the three least-squares planes discussed above, Table 2. From these and the overlay diagram shown in Fig. 2, it is apparent that the molecular structure of (I) more closely matches that observed in the polymorph reported by Venkatraman et al. (2005) rather than that described by Jian et al. (2005). This conclusion is also vindicated in the unit cell data, i.e. a = 12.225 (3), b = 7.618 (2), c = 11.639 (3) Å, β = 102.660 (4)° reported for the former (Venkatraman et al., 2005).

S2. NMR invesitgations

The conformation of (I) was also investigated in CDCl₃ solution by NMR methods. Assignments were made with the aid of the inter­pretative program, Chemdraw Ultra (CambridgeSoft Corporation, 2002). On the basis of multiple ¹H and ¹³C{¹H} resonances for the methyl groups of the propan-2-yl­idene­amino residue, it appears that the (propan-2-yl­idene­amino)­thio­urea residue has a locked configuration, consistent with the persistence of the intra­molecular N1—H···N3 hydrogen bond in CDCl₃ solution.

S3. Supra­molecular features

In the crystal, N—H···S and C—H···π inter­actions provide identifiable points of contact between molecules; these inter­actions are qu­anti­fied in Table 1. Centrosymmetrically related molecules are connected by pairs of amide-N2—H···S1 hydrogen bonds, forming eight-membered thio­amide {···HNCS}₂ synthons. These are connected into supra­molecular layers in the bc plane by amide-N1—H···S1 hydrogen bonds so that the S1 atom accepts two hydrogen bonds, Fig. 3. The p-tolyl groups protrude to either side of each layer and inter-digitate along the a axis with adjacent layers allowing for the formation of methyl-C8—H···π(C2–C7) inter­actions, thereby consolidating the three-dimensional architecture, Fig. 4.

S4. Analysis of the Hirshfeld surfaces

The crystal packing was further investigated by an analysis of the Hirshfeld surface (Spackman & Jayatilaka, 2009) employing CrystalExplorer (Wolff et al., 2012). Fingerprint plots (Rohl et al., 2008) were calculated, as were the electrostatic potentials using TONTO (Spackman et al., 2008; Jayatilaka et al., 2005) integrated into CrystalExplorer; the electrostatic potentials were mapped on the Hirshfeld surfaces using the STO–3G basis set at the level of Hartree–Fock theory over a range of ±0.075 au.

Two views of the Hirshfeld surface mapped over d_norm are shown in Figs 5a and b. The deep-red depressions at the S1 and N2 atoms (Fig. 5a) confirm their role as an acceptor and donor in the hydrogen-bonding scheme, respectively. This is also evident from the dark-red and blue regions, respectively, on the Hirshfeld surface mapped over the calculated electrostatic potential (Fig. 5c). The diminutive red spots near S1 and N1 (Fig. 5b) indicate their involvement in the inter­molecular N—H···S hydrogen bond.

The overall two-dimensional fingerprint plot (Fig. 6a) and those delineated into H···H, S···H/H···S, N···H/H···N and C···H/H···C (Figs 6b--d, respectively) inter­actions operating in the crystal structure of (I) are illustrated in Fig. 6; the relative contributions are summarized in Table 3. The prominent pair of sharp spikes of equal length (d_e + d_i = 2.45 Å; Fig. 6b) with a 15.2% contribution due to S···H/H···S contacts to the Hirshfeld surfaces also suggest the presence of these inter­actions in the crystal packing. The light-red region near N3 (Fig. 5a) and diminutive red spot near N1—H (Fig. 5b) are consistent with relatively smaller contributions from N···H/H···N contacts, i.e. 2.5 and 3.0 %, respectively, and are indicative of the weak intra­molecular hydrogen bond. The strength of such an inter­action can be visualized from the 2D fingerprint plot corresponding to N···H/ H···N contacts (Fig. 6c). The bright-orange spot in the surface mapped with d_e (within a red circle in Fig. 7) about the aryl ring and a light-blue region around the tolyl-hydrogen atom, H8C (Fig. 7), suggest a contribution from the C—H···π inter­action (Table 1). This is also evident through distinct pair of `wings' in the fingerprint plot corresponding to C···H/H···C contacts (Fig. 6d). The wing at the top, left belongs to C—H donors, while that at the bottom, right corresponds to the surface around π-acceptors with 11.3 and 7.8% contribution from C···H and H···C contacts, respectively. The H···H contacts reflected in the middle of scattered points in Fig. 6d provide the most significant contribution, i.e. 57.0%, to the Hirshfeld surface arising from a side-ways approach. The small, flat segments delineated by blue outline in the surface mapped with curvedness (Fig. 8) and the small (i.e. 0.7%) contribution from C···C contacts to the surface indicates the absence of π–π stacking inter­actions in the structure.

S5. Database survey

According to a search of the Cambridge Structural Database (Groom & Allen, 2014), there are no direct analogues of (I), either in the coordinated or uncoordinated form. As mentioned in the Structural commentary, the parent compound has been characterized in two polymorphic forms (Jian et al., 2005; Venkatraman et al., 2005). The parent compound, LH, has also been observed to coordinate metal centres. Thus, monodentate coordination via the thione-S atom was observed in a neutral complex [ZnCl₂(LH)₂] (Bel'skii et al., 1987). By contrast, a chelating mode via thione-S and imino-N atoms was observed in each of the charged complexes [CoBr(LH)₂]Br (Dessy et al., 1978) and [(η⁶-p-cymene)RuCl(LH)]Cl (Su et al., 2013). The most closely related structure having the p-tolyl substituent but variations at the imino-N atom is one where one methyl group has been substituted by a phenyl (Zhang et al., 2011). This is also a twisted molecule with the dihedral angle between the p-tolyl and NC₃ residues being 65.44 (7)°.

S6. Synthesis and crystallization

To p-tolyl iso­thio­cyanate (Sigma–Aldrich; 10 mmol, 1.49 g) in acetone (20 ml) was added hydrazine monohydrate (Sigma–Aldrich; 10 mmol, 0.76 ml). The resulting mixture was stirred for 4 h at room temperature. Both chloro­form (20 ml) and aceto­nitrile (20 ml) were then added, and the resulting mixture left for slow evaporation. Light-brown crystals were obtained after 2 weeks. Yield: 2.012 g (91%). M.p. 412–413 K. ¹H NMR (400 MHz, CDCl₃, 298 K): 9.19 (s, br, 1H, NH—N), 8.56 (s, br, 1H, NH), 7.49 (d, 2H, m-aryl, J = 8.28 Hz), 7.17 (d, 2H, o-aryl, J = 8.24 Hz), 2.34 (s, 3H, aryl-CH₃), 2.05 (s, 3H, CH₃), 1.94 (s, 3H, CH₃). ¹³C NMR (400 MHz, CDCl₃, 298 K): 176.4 [CS], 149.6 [C(CH₃)₂], 135.8 [C_ipso], 135.4 [C_para], 129.3 [C_meta], 124.5 [C_ortho], 25.3 [CH₃], 21.0 [aryl-CH₃], 16.9 [CH₃, syn to N—H]. IR (cm^-1): ν(N—H) 3240, 3168 (m), ν(C═N) 1514 (vs), ν(C—N) 1267 (s), ν(C═S) 1188 (vs).

S7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4. For (I), carbon-bound H-atoms were placed in calculated positions (C—H = 0.95–0.98 Å) and were included in the refinement in the riding model approximation, with U_iso(H) set to 1.2–1.5U_eq(C). The N-bound H-atoms were located in a difference Fourier map but were refined with a distance restraint of N—H = 0.88±0.01 Å, and with U_iso(H) set to 1.2U_eq(N).

Related literature

For related literature, see:

Computing details

Data collection: APEX2 (Bruker, 2008); cell refinement: APEX2 (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), QMol (Gans & Shalloway, 2001), DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 70% probability level.
	Fig. 2. Overlay diagram of the molecules in (I), red image, and (II), forms a (green) and b (blue). The molecules have been overlapped so that the central NC(═S)N chromophores are coincident.
	Fig. 3. Supramolecular layer in the bc plane in the crystal packing of (I). Centrosymmetric aggregates mediated by eight-membered thioamide {···HNCS}2 synthons (shown as orange dashed lines) are linked by additional amide-N—H···S hydrogen bonds, shown as blue dashed lines.
	Fig. 4. A view of the unit cell contents of (I) shown in projection down the b axis. Supramolecular layers, illustrated in Fig. 3, are linked via C—H···π interactions, shown as purple dashed lines, leading to a three-dimensional architecture.
	Fig. 5. Views of the Hirshfeld surface for (I): (a) and (b) mapped over dnorm, and (c) mapped over the calculated electrostatic potential.
	Fig. 6. 2D Fingerprint plots for (I): (a) full, (b) delineated to show S···H/H···S, (c) N···H/H···N, (d) C···H/H···C, and (e) H···H interactions.
	Fig. 7. View of the Hirshfeld surface for (I) mapped over de.
	Fig. 8. Hirshfeld surfaces for (I) mapped over curvedness.

1-(4-Methylphenyl)-3-(propan-2-ylideneamino)thiourea

Crystal data

C11H15N3S	F(000) = 472
Mr = 221.32	Dx = 1.275 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 13.7289 (13) Å	Cell parameters from 1590 reflections
b = 7.4341 (7) Å	θ = 3.0–25.5°
c = 11.5757 (11) Å	µ = 0.25 mm^−1
β = 102.690 (1)°	T = 100 K
V = 1152.58 (19) Å^3	Prism, light-brown
Z = 4	0.12 × 0.05 × 0.03 mm

Data collection

Bruker SMART APEX CCD diffractometer	2646 independent reflections
Radiation source: fine-focus sealed tube	2052 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
φ and ω scans	θmax = 27.5°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −17→17
Tmin = 0.970, Tmax = 0.993	k = −9→9
10739 measured reflections	l = −13→15

Refinement

Refinement on F^2	2 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.041	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.098	w = 1/[σ^2(Fo^2) + (0.0332P)^2 + 0.7356P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
2646 reflections	Δρmax = 0.27 e Å^−3
147 parameters	Δρmin = −0.27 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
S1	0.14991 (3)	0.10760 (6)	0.53754 (4)	0.01865 (13)
N1	0.17657 (11)	0.1754 (2)	0.31707 (14)	0.0179 (3)
H1N	0.1468 (14)	0.175 (3)	0.2419 (9)	0.023 (6)*
N2	0.01790 (11)	0.1178 (2)	0.33437 (14)	0.0174 (3)
H2N	−0.0236 (13)	0.073 (3)	0.3744 (17)	0.032 (6)*
N3	−0.00516 (11)	0.1118 (2)	0.21071 (13)	0.0177 (3)
C1	0.11491 (13)	0.1348 (2)	0.38949 (16)	0.0158 (4)
C2	0.28274 (13)	0.1793 (2)	0.34532 (16)	0.0174 (4)
C3	0.33249 (14)	0.0928 (3)	0.26883 (17)	0.0218 (4)
H3	0.2955	0.0313	0.2013	0.026*
C4	0.43587 (14)	0.0956 (3)	0.29054 (17)	0.0240 (4)
H4	0.4688	0.0357	0.2374	0.029*
C5	0.49234 (14)	0.1841 (3)	0.38822 (17)	0.0218 (4)
C6	0.44118 (15)	0.2713 (3)	0.46362 (18)	0.0240 (4)
H6	0.4781	0.3329	0.5311	0.029*
C7	0.33772 (14)	0.2703 (3)	0.44266 (17)	0.0221 (4)
H7	0.3046	0.3319	0.4949	0.027*
C8	0.60488 (15)	0.1844 (3)	0.4134 (2)	0.0316 (5)
H8A	0.6299	0.3006	0.4475	0.047*
H8B	0.6271	0.1650	0.3395	0.047*
H8C	0.6307	0.0880	0.4695	0.047*
C9	−0.09645 (13)	0.1333 (2)	0.15732 (16)	0.0163 (4)
C10	−0.18214 (14)	0.1717 (3)	0.21420 (17)	0.0220 (4)
H10A	−0.1571	0.2260	0.2922	0.033*
H10B	−0.2169	0.0592	0.2233	0.033*
H10C	−0.2285	0.2549	0.1643	0.033*
C11	−0.11855 (14)	0.1185 (3)	0.02523 (16)	0.0201 (4)
H11A	−0.0561	0.1262	−0.0024	0.030*
H11B	−0.1631	0.2166	−0.0096	0.030*
H11C	−0.1509	0.0028	0.0011	0.030*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0168 (2)	0.0218 (2)	0.0167 (2)	−0.00133 (19)	0.00219 (18)	0.00207 (18)
N1	0.0133 (8)	0.0252 (8)	0.0149 (8)	−0.0017 (6)	0.0020 (6)	0.0013 (7)
N2	0.0148 (8)	0.0226 (8)	0.0149 (8)	−0.0018 (6)	0.0033 (6)	0.0014 (6)
N3	0.0182 (8)	0.0196 (8)	0.0152 (8)	−0.0022 (6)	0.0037 (6)	0.0000 (6)
C1	0.0149 (9)	0.0129 (8)	0.0196 (9)	0.0003 (7)	0.0041 (7)	0.0007 (7)
C2	0.0151 (9)	0.0177 (8)	0.0194 (9)	−0.0003 (7)	0.0040 (7)	0.0046 (7)
C3	0.0200 (10)	0.0272 (10)	0.0181 (10)	−0.0009 (8)	0.0043 (8)	0.0008 (8)
C4	0.0194 (10)	0.0308 (11)	0.0239 (11)	0.0016 (8)	0.0092 (8)	0.0014 (8)
C5	0.0171 (10)	0.0233 (9)	0.0247 (10)	−0.0006 (8)	0.0038 (8)	0.0080 (8)
C6	0.0203 (10)	0.0258 (10)	0.0245 (11)	−0.0051 (8)	0.0018 (8)	−0.0010 (8)
C7	0.0206 (10)	0.0224 (9)	0.0251 (11)	−0.0026 (8)	0.0087 (8)	−0.0040 (8)
C8	0.0172 (10)	0.0364 (12)	0.0408 (13)	−0.0008 (9)	0.0053 (9)	0.0085 (10)
C9	0.0182 (9)	0.0121 (8)	0.0186 (9)	−0.0004 (7)	0.0041 (7)	0.0009 (7)
C10	0.0178 (10)	0.0288 (10)	0.0179 (10)	0.0056 (8)	0.0009 (8)	0.0009 (8)
C11	0.0199 (10)	0.0228 (9)	0.0167 (9)	−0.0008 (8)	0.0020 (8)	0.0004 (7)

Geometric parameters (Å, º)

S1—C1	1.6873 (18)	C5—C8	1.508 (3)
N1—C1	1.350 (2)	C6—C7	1.387 (3)
N1—C2	1.422 (2)	C6—H6	0.9500
N1—H1N	0.876 (9)	C7—H7	0.9500
N2—C1	1.350 (2)	C8—H8A	0.9800
N2—N3	1.397 (2)	C8—H8B	0.9800
N2—H2N	0.875 (9)	C8—H8C	0.9800
N3—C9	1.280 (2)	C9—C11	1.496 (2)
C2—C7	1.387 (3)	C9—C10	1.496 (3)
C2—C3	1.389 (3)	C10—H10A	0.9800
C3—C4	1.386 (3)	C10—H10B	0.9800
C3—H3	0.9500	C10—H10C	0.9800
C4—C5	1.388 (3)	C11—H11A	0.9800
C4—H4	0.9500	C11—H11B	0.9800
C5—C6	1.395 (3)	C11—H11C	0.9800
C1—N1—C2	127.79 (16)	C2—C7—C6	119.87 (18)
C1—N1—H1N	113.3 (14)	C2—C7—H7	120.1
C2—N1—H1N	117.3 (14)	C6—C7—H7	120.1
C1—N2—N3	117.72 (15)	C5—C8—H8A	109.5
C1—N2—H2N	118.4 (15)	C5—C8—H8B	109.5
N3—N2—H2N	120.2 (15)	H8A—C8—H8B	109.5
C9—N3—N2	117.91 (15)	C5—C8—H8C	109.5
N1—C1—N2	114.54 (16)	H8A—C8—H8C	109.5
N1—C1—S1	125.45 (14)	H8B—C8—H8C	109.5
N2—C1—S1	120.00 (14)	N3—C9—C11	116.21 (16)
C7—C2—C3	119.20 (17)	N3—C9—C10	126.34 (17)
C7—C2—N1	122.98 (17)	C11—C9—C10	117.46 (16)
C3—C2—N1	117.79 (17)	C9—C10—H10A	109.5
C4—C3—C2	120.30 (18)	C9—C10—H10B	109.5
C4—C3—H3	119.9	H10A—C10—H10B	109.5
C2—C3—H3	119.9	C9—C10—H10C	109.5
C3—C4—C5	121.42 (18)	H10A—C10—H10C	109.5
C3—C4—H4	119.3	H10B—C10—H10C	109.5
C5—C4—H4	119.3	C9—C11—H11A	109.5
C4—C5—C6	117.52 (17)	C9—C11—H11B	109.5
C4—C5—C8	121.55 (18)	H11A—C11—H11B	109.5
C6—C5—C8	120.92 (18)	C9—C11—H11C	109.5
C7—C6—C5	121.69 (18)	H11A—C11—H11C	109.5
C7—C6—H6	119.2	H11B—C11—H11C	109.5
C5—C6—H6	119.2
C1—N2—N3—C9	−165.78 (16)	C3—C4—C5—C6	−0.4 (3)
C2—N1—C1—N2	−171.29 (17)	C3—C4—C5—C8	178.82 (19)
C2—N1—C1—S1	9.3 (3)	C4—C5—C6—C7	0.0 (3)
N3—N2—C1—N1	11.0 (2)	C8—C5—C6—C7	−179.16 (18)
N3—N2—C1—S1	−169.57 (12)	C3—C2—C7—C6	−1.1 (3)
C1—N1—C2—C7	−50.1 (3)	N1—C2—C7—C6	−178.81 (17)
C1—N1—C2—C3	132.2 (2)	C5—C6—C7—C2	0.7 (3)
C7—C2—C3—C4	0.8 (3)	N2—N3—C9—C11	−177.62 (15)
N1—C2—C3—C4	178.60 (17)	N2—N3—C9—C10	2.4 (3)
C2—C3—C4—C5	0.0 (3)

Hydrogen-bond geometry (Å, º)

Cg1 is the centroid of the C2–C7 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···N3	0.88 (1)	2.09 (2)	2.572 (2)	114 (1)
N1—H1N···S1^i	0.88 (1)	2.87 (2)	3.5618 (17)	137 (2)
N2—H2N···S1^ii	0.88 (2)	2.57 (2)	3.4373 (16)	169 (2)
C8—H8C···Cg1^iii	0.98	2.81	3.716 (2)	154

Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x, −y, −z+1; (iii) −x+1, −y, −z+1.

 

Footnotes

‡Additional correspondence author, e-mail: [e-mail].