Acetone-4-methyl­thio­semicarbazone at 220 K

In the title compound, C₅H₁₁N₃S, the trans conformation is stabilized by a weak intramolecular N—H...N hydrogen bond. Unusually, one N—H bond is not involved in any hydrogen-bond interactions and instead the mol­ecules form a one-dimensional polymer via N—H...S intermolecular hydrogen bonds.

S1. Comment

Thiosemicarbazides and thiosemicarbazones are known to exhibit biological activity (Agrawal et al., 1972; Nandi et al., 1986; Chattopadhyay et al., 1988) including antibacterial (Nandi et al., 1984) and infertility (Nagarajan et al., 1984) properties. These properties are thought to arise from the metal chelating ability of these ligands, and this has led to considerable interest in their coordination chemistry. In almost all cases the ligands are bidentate and bind to the metal through the S and hydrazinic N atoms, although there are examples of them acting as monodentate ligands binding only through sulfur (Valdes-Martines et al., 1996). The crystal structure analysis described here is of the most simple parent compound and will provide a reference for comparison with more complex homologues.

The asymmetric unit of (I) with the atomic numbering scheme and intramolecular hydrogen bonding is shown in Figure 1. The molecule is almost planar with the maximum deviation of 0.012 Å from the least-squares plane seen for S1. The r.m.s. deviation from the least squares plane is 0.006 Å. As with related molecules the C—S bond length is indicative of a double bond, confirming that the molecule adopts the thione tautomeric form in agreement with spectroscopic data obtained for (I). Typically for this type of molecule the sulfur and hydrazinic nitrogen atoms mutually trans which allows for a weak intramolecular hydrogen bond between N4 and N2 [N4···N2 2.629 (3), H4···N2 2.18 (3), N4—H4 0.85 (3) Å, N4—H4···N2 113 (2)°]. Such contacts have been observed in other derivatives (Park & Ahn, 1985). The availability of the lone pair on N4 imparts some double bond character to the N4—C1 bond and it is shorter than that seen in 4-aryl derivatives (Palenik et al., 1974) but comparable to other reported 4-alkyl derivatives (Park & Ahn, 1985). In addition to the weak intramolecular interaction, H4 is involved in a stronger intermolecular contact to S1 in an adjacent molecule related by a c-glide plane operation [N4···S1ⁱ 3.492 (3), H4···S1ⁱ 2.69 (2), N4—H4 0.85 (3) Å, N4—H4···S1ⁱ 157 (2)° (symmetry code: (i) x, 1/2 − y, −1/2 + z)]. This is shown in Figure 1 and results in a planar one-dimensional hydrogen-bonded polymer structure. In other systems, although hydrogen bonds are prevalent, they lead to dimeric rather than polymeric structures and involve the strong hydrogen-bond donor unit N1—H1 (Chattopadhyay et al., 1988; Park & Ahn, 1985). Unusually, the hydrogen-bond donor unit N1—H1 is not involved in any intra- or inter-molecular interactions in this structure.

S2. Experimental

N(4)-Methyl thiosemicarbazide and acetone were purchased from the Aldrich Chemical Co. and used as received. The compound was synthesized by the method of Scovill (1991). The ketone and carbazide were mixed in a 1:1 ratio in absolute ethanol with a catalytic amount of concentrated sulfuric acid for 12 h. Addition of aqueous sodium hydroxide to pH 8 precipitated the product which was collected by filtration. A suitable crystal was obtained by slow cooling of a hot cyclohexane solution. Because of physical constraints on the diffractometer some of the reflections could not be accessed and the dataset was limited to 92% completion.

S3. Refinement

Methyl groups were treated as rotating rigid groups with U_iso(H) = 1.5U_eq(C); H-atoms attached to N were refined freely with isotropic displacement parameters.

Computing details

Data collection: DIF4 (Stoe & Cie, 1990a); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1990b); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997b); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1994).

Figures

Fig. 1. A view of the molecule with atom numbering scheme and showing intra and intermolecular hydrogen bonding. Displacement ellipsoids enclose 50% probability surfaces. Symmetry code (i) x, 1/2 − y, −1/2 + z.

(I)

Crystal data

C5H11N3S	F(000) = 312
Mr = 145.23	Dx = 1.254 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54178 Å
a = 7.067 (4) Å	Cell parameters from 31 reflections
b = 9.783 (5) Å	θ = 20–22°
c = 11.440 (6) Å	µ = 3.09 mm^−1
β = 103.43 (3)°	T = 220 K
V = 769.3 (7) Å^3	Plate developed in (001), colourless
Z = 4	0.42 × 0.31 × 0.12 mm

Data collection

Stoe Stadi-4 diffractometer equipped with an Oxford Cryosystems open flow cryostat device.	1181 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.013
Graphite monochromator	θmax = 69.9°, θmin = 6.0°
ω–θ scans	h = −7→8
Absorption correction: optimised numerical A numerical absorption was performed by Gaussian integration after refinement of the crystal form and dimensions against a set of ψ scans (X-SHAPE; Stoe & Cie, 1997).	k = −7→11
Tmin = 0.302, Tmax = 0.658	l = −12→13
2687 measured reflections	3 standard reflections every 60 min
1348 independent reflections	intensity decay: +/−1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.122	w = 1/[σ^2(Fo^2) + (0.0622P)^2 + 0.705P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.018
1348 reflections	Δρmax = 0.30 e Å^−3
94 parameters	Δρmin = −0.40 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997a), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0144 (15)

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	0.26869 (10)	0.14281 (6)	0.64775 (5)	0.0360 (3)
C1	0.2538 (3)	0.2408 (2)	0.5243 (2)	0.0290 (6)
N1	0.2563 (3)	0.3793 (2)	0.53596 (19)	0.0332 (5)
H1	0.270 (4)	0.415 (3)	0.603 (3)	0.036 (8)*
N2	0.2411 (3)	0.4609 (2)	0.43562 (18)	0.0306 (5)
C3	0.2443 (3)	0.5906 (2)	0.4509 (2)	0.0288 (6)
C31	0.2621 (4)	0.6599 (3)	0.5697 (2)	0.0402 (7)
H31A	0.2545	0.7581	0.5580	0.060*
H31B	0.3861	0.6365	0.6227	0.060*
H31C	0.1572	0.6300	0.6053	0.060*
C32	0.2273 (4)	0.6770 (3)	0.3415 (2)	0.0365 (6)
H32A	0.3421	0.7340	0.3506	0.055*
H32B	0.1127	0.7345	0.3311	0.055*
H32C	0.2159	0.6187	0.2716	0.055*
N4	0.2394 (3)	0.1933 (2)	0.41414 (19)	0.0335 (5)
H4	0.247 (4)	0.255 (3)	0.363 (2)	0.027 (7)*
C41	0.2341 (5)	0.0490 (3)	0.3840 (3)	0.0428 (7)
H41A	0.3637	0.0107	0.4099	0.064*
H41B	0.1889	0.0381	0.2977	0.064*
H41C	0.1463	0.0019	0.4241	0.064*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0502 (5)	0.0286 (4)	0.0314 (4)	0.0003 (3)	0.0141 (3)	0.0064 (2)
C1	0.0300 (14)	0.0261 (12)	0.0318 (12)	0.0002 (9)	0.0090 (9)	0.0000 (9)
N1	0.0514 (15)	0.0223 (10)	0.0269 (11)	−0.0003 (9)	0.0115 (9)	0.0003 (8)
N2	0.0416 (13)	0.0240 (10)	0.0273 (10)	−0.0004 (8)	0.0103 (9)	0.0014 (8)
C3	0.0298 (14)	0.0243 (12)	0.0324 (12)	−0.0010 (9)	0.0076 (10)	0.0000 (9)
C31	0.0527 (19)	0.0291 (14)	0.0385 (14)	−0.0016 (11)	0.0102 (12)	−0.0068 (11)
C32	0.0479 (17)	0.0243 (12)	0.0377 (14)	−0.0007 (11)	0.0108 (12)	0.0026 (10)
N4	0.0496 (14)	0.0217 (10)	0.0314 (11)	−0.0007 (9)	0.0139 (9)	0.0011 (9)
C41	0.062 (2)	0.0254 (14)	0.0422 (14)	0.0016 (12)	0.0140 (13)	−0.0060 (11)

Geometric parameters (Å, º)

S1—C1	1.689 (2)	N2—C3	1.281 (3)
C1—N4	1.325 (3)	C3—C32	1.492 (3)
C1—N1	1.361 (3)	C3—C31	1.497 (3)
N1—N2	1.382 (3)	N4—C41	1.451 (3)
N4—C1—N1	116.0 (2)	N2—C3—C32	116.8 (2)
N4—C1—S1	124.93 (19)	N2—C3—C31	124.6 (2)
N1—C1—S1	119.08 (18)	C32—C3—C31	118.6 (2)
C1—N1—N2	119.8 (2)	C1—N4—C41	124.0 (2)
C3—N2—N1	117.6 (2)