1-(4-Methyl­amino-1,2,5-thia­diazo­le-3-carbonyl)­thio­semicarbazide

In the title compound, C₅H₈N₆OS₂, the supramol­ecular architecture is sustained by two N—H...O and three N—H...S hydrogen bonds, and by N...S electrostatic interactions. The hydrogen-bond network generates a sheet structure, which extends in the a and b directions and is one c-cell dimension thick. These extended sheets are then linked across inversion centres in the c direction by N...S electrostatic interactions, thus forming a three-dimensional network. The principal intermolecular dimensions include N(H)...O distances of 2.8393 (17) and 3.0268 (16) Å, N(H)...S distances in the range 3.2896 (14)–3.5924 (16) Å and N...S distances of 3.0822 (16) Å.

S1. Comment

Thiosemicarbazides and their derivatives are widely used as ligands for the sensing of metal cations (Busev, 1972). In addition, the close intermolecular N···S contacts that have been observed for a variety of compounds containing thiadiazole or thiadiazine rings (Suzuki et al., 1992; Suzuki et al., 1997; Yamashita et al., 1990; Daley et al., 1984) are an interesting feature of the ═N—S—N═linkage. These contacts may be due to an intermolecular electrostatic interaction between –N—S⁺═N– dipoles and/or weak intermolecular bonding involving a partial rehybridization at the S atom, with d-orbital participation (Gieren et al., 1979).

The title compound, C₅H₈N₆OS₂, (I), crystallizes in space group P-1. Bond lengths and angles in (I) agree with the corresponding values in related compounds (Yamaguchi et al., 1990; Kivikoski et al., 1990). In (I) (Fig. 1), the N-methylated amine group and the neighboring carbonyl O atom are essentially in the plane of the thiadiazole ring, and the folded conformation of the molecule is sustained by the intramolecular N—H···O hydrogen bond [N4···O1 = 2.839 (2) Å; Table 2] that closes the six-membered ring. The conjugated thiadiazole and hydrogen-bonded rings afford a practically planar bicyclic system, with a dihedral angle between the two rings of 2.02 (5) °.

The supramolecular architecture is generated by two N—H···O and three N—H···S hydrogen bonds, and by N···S electrostatic interactions. The N—H···O hydrogen bonds are responsible for linking adjacent molecules of (I) into a centrosymmetric tetramer. Carbonyl atom O1 acts as an acceptor, via atoms H31 and H32, in a three-centre hydrogen bond with the amine function [N3···O1(-x + 1, −y, −z + 1) = 2.9830 (17) Å and N3···O1(x − 1, y, z) = 3.0268 (16) Å; Fig. 2]. The combination of these two three-centre interactions affords a cyclic R²₂(8) synthon (Etter, 1990; Bernstein et al., 1995), and the propagation of this motif along the [100] direction generates chains. The robustness of the chains is also sustained by the N(H)···S interaction between the methylated N4 and thiosemicarbazide S1 atoms. Two such interactions [N4···S1(-x + 2, −y, −z + 1) = 3.5924 (16) Å] related by the inversion center close the 18-membered R₂²(18) ring (Fig. 2).

These chains are then linked into sheets via two N—H···S hydrogen bonds (Fig. 3). The N1—N2 hydrazine bridge acts as a hydrogen-bond donor, via atoms H1 and H2, to S1 atoms in two symmetry-realted molecules [N1···S1(-x + 1, −y + 1, −z + 1) = 3.3446 (14) Å and N2···S1(-x + 2, −y + 1, −z + 1) = 3.2896 (14) Å]. In this manner, a chain of edge-fused (along the S1–C8 covalent bond) R²₂(8) and R²₂(10) rings running parallel to [100] is generated by translation. The dihedral angle between the planes defined by the atoms composing the eight-membered and ten-membered rings is 97.5 (2)°. A similar H-atom-closed ten-membered ring based on the thiosemicarbazide branch was found in the demethylated analogue of (I) in its cocrystal with 18-crown-6 (Fonari et al., 2003). Thus, the sheets arranged parallel to the (110) plane are sustained by N—H···O and N—H···S hydrogen bonds.

The neighboring sheets, which are a c-cell translation thick and which lie along the [001] direction, are connected by secondary bonding (Starbuck et al., 1999), viz. N6···S2(1 − x, −y, 2 − z) contacts [3.0822 (16) Å], into three-dimensional network (Fig. 4). This contact distance is significantly shorter than the sum of the van der Waals radii for the N and S atoms (3.35 Å) and leads to a centrosymmetric parallelogram whose sides are the S2—N6 bond [1.632 (2) Å] and the 3.0822 (16) Å intermolecular contact. A search of the Cambridge Structural Database (CSD; November 2002 release; Allen, 2002) for related molecules resulted in 17 structures, with preferentially centrosymmeric interactions between the thiadiazole rings in the range 3.022–3.268 Å. The molecules of (I) in the neighboring sheets are uniformly stacked along the a axis, with centroid–centroid separations of 4.660 (1) Å (the a axis cell length). A similar stacking arrangement of the thiadiazole rings has been found in 4,7-dimethyl-4,7-dihydro[1,2,5]thiadiazolo-[3,4-b]pyrazine (plane–plane distance = 3.35 Å; Yamashita et al., 1990), in thiadiazole derivative of tetracyanoquinodimethane (3.48 Å; Suzuki et al., 1992) and in the naphtho-derivative of bis(1,2,6)thiadiazine [3.794 Å, which is equal in length to the c axis; Gieren et al., 1979).

S2. Experimental

The hydrazide of 4-methylamino-(1,2,5)-thiadiazole-3-carbonic acid was obtained from the ethyl ester of 4-methylamino-(1,2,5)-thiadiazole-3-carbonic acid as described by Ivanov et al. (1992). To a mixture of the hydrazide (3.18 g, 0.02 mol) of 4-methylamino(1,2,5)-thiadiazole-3-carbonic acid and ammonium isothiocyanate (1.52 g, 0.02 mol) in water (70 ml) was added concentrated hydrochloric acid (2.0 ml). The reaction mixture was boiled for 3 h in a water bath. A precipitate that formed after the hot solution was cooled to room temperature was then recrystallized from methanol/ethyl acetate (1:1) via solvent evaporation to give colorless crystals of (I) after 2–3 d (m.p. 519–520 K) Analysis found: S 31.95, N 13.75%; C₅H₈N₆OS₂ requires: S 32.07, N 14.01%.

S3. Refinement

Methyl H atoms were included in calculated positions and refined with isotropic displacement parameters according to the riding model, while H atoms bound to N atoms were found from Fourier maps and were treated isotropically subject to a DFIX restraint.

Computing details

Data collection: KM4 Software (Galdecki et al., 1996); cell refinement: KM4 Software; data reduction: KM4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the structure of (I), showing displacement ellipsoids at the 50% probability level. The dashed lines designate the intramolecular hydrogen bond.
	Fig. 2. Part of the crystal structure of (I), showing the formation of a hydrogen-bonded chain. Atoms marked with an asterisk (*) or hash (#) are at the symmetry positions (-x + 1, −y, −z + 1) and (x − 1, y, z), respectively.
	Fig. 3. Part of the crystal structure of (I), showing the formation of an edge-fused chain of R^22(8) and R^22(10) rings along [100]. Atoms marked with an asterisk (*) or hash (#) are at the symmetry positions (-x + 1, −y + 1, −z + 1) and (-x + 2, −y + 1, −z + 1), respectively.
	Fig. 4. The three-dimensional network in (I), sustained by secondary N···S interactions.

Thioamide hydrazide of 4-N-methylamino-3-carbonic acid

Crystal data

C5H8N6OS2	Z = 2
Mr = 232.29	F(000) = 240
Triclinic, P1	Dx = 1.548 Mg m^−3
a = 4.660 (1) Å	Mo Kα radiation, λ = 0.71070 Å
b = 7.288 (2) Å	Cell parameters from 24 reflections
c = 14.868 (4) Å	θ = 5.6–16.2°
α = 95.28 (1)°	µ = 0.51 mm^−1
β = 91.97 (1)°	T = 293 K
γ = 97.21 (1)°	Prism, pale yellow
V = 498.3 (2) Å^3	0.35 × 0.20 × 0.15 mm

Data collection

KUMA KM-4 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 34.9°, θmin = 2.8°
Graphite monochromator	h = 0→7
ω–2θ scans	k = −11→11
4300 measured reflections	l = −23→23
4300 independent reflections	3 standard reflections every 100 reflections
3297 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0463P)^2 + 0.1303P] where P = (Fo^2 + 2Fc^2)/3
4300 reflections	(Δ/σ)max = 0.001
148 parameters	Δρmax = 0.36 e Å^−3
5 restraints	Δρmin = −0.44 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
S1	0.70747 (7)	0.32958 (5)	0.38184 (2)	0.03459 (9)
S2	0.46198 (9)	0.19226 (6)	0.91932 (2)	0.04630 (11)
O1	0.9639 (2)	0.09447 (14)	0.65215 (6)	0.0378 (2)
N1	0.6526 (2)	0.30818 (17)	0.64399 (7)	0.0338 (2)
H1	0.546 (4)	0.379 (3)	0.6720 (12)	0.054 (5)*
N2	0.7428 (2)	0.34744 (16)	0.55940 (7)	0.0333 (2)
H2	0.889 (4)	0.431 (2)	0.5592 (12)	0.048 (5)*
N3	0.3273 (2)	0.18300 (16)	0.49303 (8)	0.0345 (2)
H31	0.224 (4)	0.141 (2)	0.4443 (10)	0.047 (5)*
H32	0.272 (4)	0.162 (3)	0.5459 (10)	0.055 (5)*
N4	0.9296 (3)	−0.11974 (19)	0.80248 (8)	0.0447 (3)
H4	0.995 (4)	−0.123 (3)	0.7501 (11)	0.058 (6)*
N5	0.5226 (3)	0.26782 (17)	0.82136 (7)	0.0391 (2)
N6	0.6450 (3)	0.01510 (19)	0.91095 (8)	0.0427 (3)
C1	0.6884 (3)	0.15662 (18)	0.77883 (7)	0.0315 (2)
C2	0.7623 (3)	0.00924 (19)	0.83020 (8)	0.0345 (2)
C7	0.7830 (3)	0.18317 (17)	0.68717 (7)	0.0290 (2)
C8	0.5794 (2)	0.28229 (16)	0.48400 (7)	0.0272 (2)
C9	0.9734 (5)	−0.2723 (2)	0.85480 (13)	0.0584 (4)
H9A	1.0425	−0.2245	0.9150	0.088*
H9B	1.1133	−0.3425	0.8269	0.088*
H9C	0.7933	−0.3514	0.8572	0.088*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.03707 (16)	0.04536 (18)	0.02442 (13)	0.01179 (13)	0.00761 (11)	0.00862 (11)
S2	0.0547 (2)	0.0600 (2)	0.02679 (15)	0.01054 (17)	0.01389 (14)	0.00926 (14)
O1	0.0431 (5)	0.0428 (5)	0.0308 (4)	0.0125 (4)	0.0104 (4)	0.0092 (4)
N1	0.0356 (5)	0.0451 (6)	0.0243 (4)	0.0110 (4)	0.0083 (4)	0.0118 (4)
N2	0.0313 (5)	0.0455 (6)	0.0240 (4)	0.0013 (4)	0.0038 (4)	0.0133 (4)
N3	0.0319 (5)	0.0414 (6)	0.0305 (5)	0.0036 (4)	0.0043 (4)	0.0053 (4)
N4	0.0584 (8)	0.0476 (7)	0.0327 (6)	0.0156 (6)	0.0072 (5)	0.0142 (5)
N5	0.0447 (6)	0.0460 (6)	0.0282 (5)	0.0076 (5)	0.0090 (4)	0.0075 (4)
N6	0.0493 (7)	0.0539 (7)	0.0266 (5)	0.0046 (5)	0.0065 (4)	0.0137 (5)
C1	0.0344 (6)	0.0386 (6)	0.0218 (5)	0.0025 (5)	0.0036 (4)	0.0069 (4)
C2	0.0375 (6)	0.0405 (6)	0.0256 (5)	0.0010 (5)	0.0011 (4)	0.0096 (4)
C7	0.0310 (5)	0.0342 (6)	0.0217 (4)	0.0014 (4)	0.0025 (4)	0.0057 (4)
C8	0.0292 (5)	0.0296 (5)	0.0263 (5)	0.0126 (4)	0.0054 (4)	0.0076 (4)
C9	0.0754 (12)	0.0492 (9)	0.0563 (10)	0.0171 (8)	0.0045 (9)	0.0225 (8)

Geometric parameters (Å, º)

S1—C8	1.6996 (12)	N3—H32	0.856 (14)
S2—N5	1.6251 (12)	N4—C2	1.340 (2)
S2—N6	1.6320 (15)	N4—C9	1.445 (2)
O1—C7	1.2268 (15)	N4—H4	0.844 (15)
N1—C7	1.3532 (16)	N5—C1	1.3231 (18)
N1—N2	1.3830 (14)	N6—C2	1.3356 (17)
N1—H1	0.854 (15)	C1—C2	1.4427 (18)
N2—C8	1.3472 (16)	C1—C7	1.4687 (16)
N2—H2	0.853 (14)	C9—H9A	0.9600
N3—C8	1.3181 (16)	C9—H9B	0.9600
N3—H31	0.864 (14)	C9—H9C	0.9600
N5—S2—N6	99.22 (6)	C2—C1—C7	124.15 (12)
C7—N1—N2	118.46 (11)	N6—C2—N4	122.61 (12)
C7—N1—H1	121.1 (13)	N6—C2—C1	112.04 (13)
N2—N1—H1	119.0 (14)	N4—C2—C1	125.35 (11)
C8—N2—N1	121.17 (10)	O1—C7—N1	122.81 (11)
C8—N2—H2	122.4 (12)	O1—C7—C1	121.71 (11)
N1—N2—H2	115.5 (12)	N1—C7—C1	115.46 (11)
C8—N3—H31	117.6 (12)	N3—C8—N2	118.16 (10)
C8—N3—H32	119.7 (13)	N3—C8—S1	122.96 (9)
H31—N3—H32	122.7 (17)	N2—C8—S1	118.88 (9)
C2—N4—C9	121.90 (13)	N4—C9—H9A	109.5
C2—N4—H4	120.6 (14)	N4—C9—H9B	109.5
C9—N4—H4	116.9 (14)	H9A—C9—H9B	109.5
C1—N5—S2	107.22 (9)	N4—C9—H9C	109.5
C2—N6—S2	107.59 (10)	H9A—C9—H9C	109.5
N5—C1—C2	113.94 (11)	H9B—C9—H9C	109.5
N5—C1—C7	121.91 (11)
C7—N1—N2—C8	105.95 (14)	N5—C1—C2—N4	−179.25 (13)
N6—S2—N5—C1	−0.02 (11)	C7—C1—C2—N4	1.3 (2)
N5—S2—N6—C2	0.22 (11)	N2—N1—C7—O1	−4.91 (19)
S2—N5—C1—C2	−0.19 (14)	N2—N1—C7—C1	176.51 (10)
S2—N5—C1—C7	179.23 (9)	N5—C1—C7—O1	171.10 (12)
S2—N6—C2—N4	179.28 (12)	C2—C1—C7—O1	−9.54 (19)
S2—N6—C2—C1	−0.35 (14)	N5—C1—C7—N1	−10.30 (18)
C9—N4—C2—N6	5.8 (2)	C2—C1—C7—N1	169.06 (12)
C9—N4—C2—C1	−174.62 (15)	N1—N2—C8—N3	1.44 (18)
N5—C1—C2—N6	0.37 (17)	N1—N2—C8—S1	−178.02 (9)
C7—C1—C2—N6	−179.04 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···S1^i	0.85 (2)	2.72 (2)	3.3446 (14)	131 (2)
N2—H2···S1^ii	0.85 (1)	2.48 (1)	3.2896 (14)	159 (2)
N3—H31···O1^iii	0.86 (1)	2.20 (2)	2.9830 (17)	150 (2)
N3—H32···O1^iv	0.86 (1)	2.22 (2)	3.0268 (16)	157 (2)
N4—H4···O1	0.84 (2)	2.26 (2)	2.8393 (16)	126 (2)
N4—H4···S1^v	0.84 (2)	2.86 (2)	3.5924 (16)	146 (2)

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