1-(Thio­phen-2-yl)ethanone thio­semi­carbazone

Gaye, P.A.; Sy, A.; Sarr, A.D.; Gaye, M.; Besnard, C.

doi:10.1107/S1600536811011986

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 5| May 2011| Page o1168

doi:10.1107/S1600536811011986

Open

access

1-(Thiophen-2-yl)ethanone thiosemicarbazone

Papa Aly Gaye,^a Adama Sy,^a Aminata Diassé Sarr,^a Mohamed Gaye ^a ^* and Celine Besnard ^b

^aDépartement de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, and ^bLaboratoire de Cristallochimie, Ecole de Physique, 24 Quai Ernest-Ansermet, 1211 Gebeve, Switzerland
^*Correspondence e-mail: mlgayeastou@yahoo.fr

(Received 17 March 2011; accepted 31 March 2011; online 16 April 2011)

The title compound, C₇H₉N₃S₂, crystallizes with two unique molecules in the unit cell, both present as thiosemicarbazide tautomers. The molecules differ principally in the dihedral angles between the thiophene ring planes and the planes through the non-H atoms of the hydrazinecarbothioamide units, viz. 9.80 (8)° for one molecule and 19.37 (7)° for the other. The hydrazinecarbothioamide units are reasonably planar, with r.m.s. deviations of 0.001Å for each of the molecules. In the crystal, N—H⋯S hydrogen bonds link like molecules into R₂²(8) inversion dimers. A three-dimensional network structure is generated by additional N—H⋯S hydrogen bonds and weak C—H⋯S contacts between the unique molecules.

Related literature

For related structures, see: Avsar et al. (2003 ); Arslan et al. (2004 ); Kusaï et al. (2009 ). For graph-set motifs, see: Bernstein et al. (1995 ). For the weighting scheme, see: Prince (1982 ); Watkin (1994 ).

Experimental

Crystal data

C₇H₉N₃S₂
M_r = 199.31
Triclinic, $[P \overline 1]$
a = 9.0037 (9) Å
b = 9.7800 (9) Å
c = 12.1428 (12) Å
α = 104.575 (8)°
β = 103.345 (8)°
γ = 108.227 (8)°
V = 925.52 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.52 mm⁻¹
T = 140 K
0.50 × 0.40 × 0.30 mm

Data collection

Stoe IPDS diffractometer
13175 measured reflections
5386 independent reflections
4634 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.053
S = 1.00
5373 reflections
217 parameters
H-atom parameters constrained
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.39 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11⋯S3ⁱ	0.83	2.56	3.3609 (16)	162
N21—H212⋯S3ⁱⁱ	0.83	2.66	3.4691 (16)	167
N24—H241⋯S23ⁱⁱⁱ	0.85	2.77	3.6128 (14)	174
C7—H72⋯S23ⁱⁱ	0.98	2.83	3.7236 (16)	153
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) -x, -y+2, -z+1; (iii) -x, -y+2, -z.

Data collection: IPDS (Stoe & Cie, 1996 ); cell refinement: IPDS; data reduction: X-RED (Stoe & Cie 1996); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007 ); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ); molecular graphics: CAMERON (Watkin et al., 1996 ); software used to prepare material for publication: CRYSTALS.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811011986/pb2061sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811011986/pb2061Isup2.hkl

checkCIF report

Comment top

NMR analysis of the title compound, (C₇H₉N₃S₂)₂, (see experimental) shows that two forms are present in solution with the thiosemicarbazide moiety being partially transformed into the thioenolsemicarbazide. The X-ray structure determination reveals that the compound crystallizes in the triclinic space group P-1 with two molecules in the asymmetric unit, both of which are present as the thiosemicarbazide tautomer. The molecular geometry is illustrated in Fig. 1. The C—S bond lengths 1.6921 (15) Å and 1.6884 (15) Å confirm the double bond character and are comparable to those observed for 1-(biphenyl-4-carbonyl)-3-p-tolyl-thiourea [1.647 (3) Å for C—S, 1.217 (3) and 1.224 (3) Å] (Avsar et al., 2003). The C—N bond lengths are in the range [1.2920 (17) - 1.4122 (16) Å] which are shorter than normal single C—N bond lengths (Arslan et al., 2004).

Both unique molecules form inversion related dimers with R²₂(8) graph-set motifs (Bernstein et al., 1995) through N1—H11···S3 and N24—H241···S23 hydrogen bonds. Unique molecules are further linked by N21—H212···S3 bonds supported by a weak C7—H72···S3 contacts which generate additional centrosymmetric R²₂(11) motifs and a three dimensional network (Fig. 2).

Related literature top

For related structures, see: Avsar et al. (2003); Arslan et al. (2004); Kusaï et al. (2009). For graph-set motifs, see: Bernstein et al. (1995). For the weighting scheme, see: Prince (1982); Watkin (1994).

Experimental top

2-Acetyl thiophene (1,2618 g, 10 mmol) was reacted with thiosemicarbazide (0.9114 g, 10 mmol) in CH₃OH (50 ml) solution, to give the corresponding compound after one hour under reflux. After cooling to room temperature, a yellow solid was isolated and washed twice with diethyl ether. Yield: 79.5%. m.p. 142–146 °C. Anal. Calc. for C₇H₉N₃S₂ (%): C, 42.19; H, 4.55; N, 21.08. Found: C, 42.22; H, 4.53; N, 21.01. Selected IR data (cm^-1, KBr pellet): 3450, 3250 (ν NH), 1630 (ν C=N), 1160 (ν C=S). ¹H NMR (200 MHz, CD₆Cl, δ, p.p.m.): 2.32 (s, 3H, –CH₃); 7.42 (s, 2H, –NH₂); 8.32 (s, 1H, –NH); 7.07–7.58 (m, 3H, C₄H₃S); 10.36 (s, 1H, SH);. ¹³C NMR (200 MHz, CD₃Cl, δ, p.p.m.): 14.01 (–CH₃); 68.09 (O—CH~2~); 70.12 (O– CH~2~); 127.12–143.152 (C₄H₃S); 145.30 (C=N); 178.02 (C=S). A CH₃Cl solution of the title compound was mixed with ethanol (1/1). After several days, colorless block-shaped single crystals suitable for X-ray crystallographic analysis were obtained.

Computing details top

Data collection: IPDS (Stoe & Cie, 1996); cell refinement: IPDS (Stoe & Cie, 1996); data reduction: X-RED (Stoe & Cie 1996); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top

	Fig. 1. The asymmetric unit of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Crystal packing of 1 viewed down the b axis. Hydrogen bonds are drawn as dashed lines.

1-(Thiophen-2-yl)ethanone thiosemicarbazone top

Crystal data top

C₇H₉N₃S₂	Z = 4
M_r = 199.31	F(000) = 416
Triclinic, P1	D_x = 1.430 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 9.0037 (9) Å	Cell parameters from 0 reflections
b = 9.7800 (9) Å	θ = 0–0°
c = 12.1428 (12) Å	µ = 0.52 mm⁻¹
α = 104.575 (8)°	T = 140 K
β = 103.345 (8)°	Parallelepiped, yellow
γ = 108.227 (8)°	0.50 × 0.40 × 0.30 mm
V = 925.52 (18) Å³

Data collection top

Stoe IPDS diffractometer	R_int = 0.033
Graphite monochromator	θ_max = 30.9°, θ_min = 2.3°
ω scans	h = −12→12
13175 measured reflections	k = −12→13
5386 independent reflections	l = −17→17
4634 reflections with I > 2σ(I)

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.034	H-atom parameters constrained
wR(F²) = 0.053	Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982) [weight] = 1.0/[A₀T₀(x) + A₁T₁(x) ··· + A_n-1]T_n-1(x)] where A_i are the Chebychev coefficients listed below and x = F /Fmax Method = Robust Weighting (Prince, 1982) W = [weight] [1-(deltaF/6*sigmaF)²]² A_i are: 17.0 19.0 6.62
S = 1.00	(Δ/σ)_max = 0.001
5373 reflections	Δρ_max = 0.40 e Å⁻³
217 parameters	Δρ_min = −0.39 e Å⁻³
0 restraints

Crystal data top

C₇H₉N₃S₂	γ = 108.227 (8)°
M_r = 199.31	V = 925.52 (18) Å³
Triclinic, P1	Z = 4
a = 9.0037 (9) Å	Mo Kα radiation
b = 9.7800 (9) Å	µ = 0.52 mm⁻¹
c = 12.1428 (12) Å	T = 140 K
α = 104.575 (8)°	0.50 × 0.40 × 0.30 mm
β = 103.345 (8)°

Data collection top

Stoe IPDS diffractometer	4634 reflections with I > 2σ(I)
13175 measured reflections	R_int = 0.033
5386 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.053	H-atom parameters constrained
S = 1.00	Δρ_max = 0.40 e Å⁻³
5373 reflections	Δρ_min = −0.39 e Å⁻³
217 parameters

Special details top

Experimental. Reflections affected by the beam-stop were not included in the refinement.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.26295 (15)	0.85450 (15)	0.42449 (11)	0.0287
C2	0.23744 (17)	0.93285 (17)	0.51896 (12)	0.0224
S3	0.37191 (5)	1.11020 (4)	0.61614 (4)	0.0264
N4	0.09273 (14)	0.86531 (14)	0.53590 (11)	0.0255
N5	−0.00908 (14)	0.71581 (14)	0.46373 (11)	0.0234
C6	−0.13491 (16)	0.65062 (17)	0.49325 (12)	0.0217
C7	−0.17662 (18)	0.72896 (18)	0.59706 (13)	0.0276
C8	−0.23815 (16)	0.49066 (17)	0.41921 (13)	0.0222
S9	−0.19349 (5)	0.39888 (5)	0.29754 (4)	0.0286
C10	−0.35441 (19)	0.22919 (18)	0.26747 (15)	0.0313
C11	−0.43840 (19)	0.24169 (18)	0.34678 (15)	0.0295
C12	−0.37117 (18)	0.39098 (17)	0.43411 (14)	0.0260
N21	−0.13026 (16)	0.79416 (16)	0.21760 (12)	0.0317
C22	−0.07537 (17)	0.87345 (17)	0.15117 (12)	0.0240
S23	−0.15386 (5)	0.99727 (5)	0.11278 (4)	0.0283
N24	0.05087 (15)	0.85422 (14)	0.11585 (11)	0.0245
N25	0.10126 (15)	0.74112 (14)	0.13786 (10)	0.0233
C26	0.22938 (17)	0.73180 (16)	0.11099 (12)	0.0213
C27	0.33339 (19)	0.83708 (19)	0.06322 (15)	0.0311
C28	0.27075 (17)	0.60356 (16)	0.12664 (12)	0.0210
S29	0.14366 (5)	0.46442 (5)	0.16514 (4)	0.0294
C30	0.2690 (2)	0.36424 (19)	0.15960 (14)	0.0324
C31	0.4021 (2)	0.43291 (19)	0.13032 (15)	0.0314
C32	0.40373 (19)	0.57103 (18)	0.11115 (14)	0.0282
H71	−0.2700	0.6650	0.6064	0.0418*
H73	−0.1962	0.8165	0.5899	0.0414*
H72	−0.0819	0.7680	0.6714	0.0395*
H101	−0.3781	0.1398	0.2028	0.0387*
H111	−0.5275	0.1609	0.3456	0.0342*
H121	−0.4131	0.4187	0.4973	0.0309*
H271	0.4474	0.8480	0.0869	0.0485*
H273	0.3333	0.9390	0.0904	0.0470*
H272	0.2894	0.8001	−0.0250	0.0484*
H301	0.2423	0.2727	0.1735	0.0391*
H311	0.4849	0.3958	0.1244	0.0388*
H321	0.4848	0.6364	0.0904	0.0338*
H41	0.0815	0.9026	0.6019	0.0329*
H241	0.0787	0.8967	0.0667	0.0309*
H12	0.1936	0.7641	0.3821	0.0374*
H211	−0.0889	0.7344	0.2366	0.0407*
H11	0.3561	0.8847	0.4174	0.0369*
H212	−0.2011	0.8090	0.2464	0.0402*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0205 (6)	0.0368 (7)	0.0220 (6)	0.0057 (5)	0.0103 (5)	0.0038 (5)
C2	0.0188 (6)	0.0292 (7)	0.0221 (6)	0.0107 (5)	0.0084 (5)	0.0108 (6)
S3	0.02314 (17)	0.02531 (17)	0.03061 (19)	0.00811 (14)	0.01403 (15)	0.00688 (15)
N4	0.0206 (6)	0.0279 (6)	0.0274 (6)	0.0080 (5)	0.0136 (5)	0.0058 (5)
N5	0.0191 (5)	0.0264 (6)	0.0245 (6)	0.0089 (5)	0.0085 (5)	0.0075 (5)
C6	0.0174 (6)	0.0298 (7)	0.0221 (6)	0.0116 (5)	0.0084 (5)	0.0114 (6)
C7	0.0236 (7)	0.0346 (8)	0.0257 (7)	0.0107 (6)	0.0129 (6)	0.0086 (6)
C8	0.0185 (6)	0.0293 (7)	0.0238 (7)	0.0125 (5)	0.0093 (5)	0.0115 (6)
S9	0.02536 (18)	0.03112 (19)	0.03085 (19)	0.01106 (15)	0.01547 (15)	0.00804 (15)
C10	0.0276 (7)	0.0267 (7)	0.0396 (9)	0.0120 (6)	0.0135 (7)	0.0079 (7)
C11	0.0253 (7)	0.0270 (7)	0.0417 (9)	0.0122 (6)	0.0152 (7)	0.0148 (7)
C12	0.0225 (7)	0.0309 (7)	0.0327 (8)	0.0136 (6)	0.0150 (6)	0.0152 (6)
N21	0.0333 (7)	0.0477 (8)	0.0356 (7)	0.0287 (6)	0.0220 (6)	0.0234 (6)
C22	0.0235 (7)	0.0300 (7)	0.0188 (6)	0.0144 (6)	0.0068 (5)	0.0044 (5)
S23	0.03127 (19)	0.0329 (2)	0.03109 (19)	0.02194 (16)	0.01527 (16)	0.01188 (16)
N24	0.0271 (6)	0.0323 (6)	0.0242 (6)	0.0197 (5)	0.0130 (5)	0.0119 (5)
N25	0.0249 (6)	0.0293 (6)	0.0210 (6)	0.0165 (5)	0.0091 (5)	0.0088 (5)
C26	0.0201 (6)	0.0269 (7)	0.0170 (6)	0.0114 (5)	0.0052 (5)	0.0059 (5)
C27	0.0293 (8)	0.0347 (8)	0.0405 (9)	0.0175 (7)	0.0173 (7)	0.0198 (7)
C28	0.0209 (6)	0.0259 (7)	0.0173 (6)	0.0109 (5)	0.0071 (5)	0.0066 (5)
S29	0.03128 (19)	0.0318 (2)	0.0328 (2)	0.01480 (16)	0.01744 (16)	0.01445 (16)
C30	0.0462 (9)	0.0327 (8)	0.0278 (7)	0.0228 (7)	0.0162 (7)	0.0134 (6)
C31	0.0376 (8)	0.0386 (9)	0.0317 (8)	0.0266 (7)	0.0163 (7)	0.0154 (7)
C32	0.0264 (7)	0.0351 (8)	0.0305 (8)	0.0177 (6)	0.0134 (6)	0.0128 (6)

Geometric parameters (Å, º) top

N1—C2	1.3210 (17)	N21—C22	1.3249 (19)
N1—H12	0.845	N21—H211	0.836
N1—H11	0.831	N21—H212	0.828
C2—S3	1.6921 (15)	C22—S23	1.6884 (15)
C2—N4	1.3528 (17)	C22—N24	1.3525 (17)
N4—N5	1.3754 (17)	N24—N25	1.3811 (16)
N4—H41	0.836	N24—H241	0.849
N5—C6	1.2920 (17)	N25—C26	1.2923 (17)
C6—C7	1.4931 (19)	C26—C27	1.491 (2)
C6—C8	1.455 (2)	C26—C28	1.4586 (19)
C7—H71	0.928	C27—H271	0.963
C7—H73	0.947	C27—H273	0.969
C7—H72	0.978	C27—H272	0.977
C8—S9	1.7270 (14)	C28—S29	1.7243 (14)
C8—C12	1.3696 (19)	C28—C32	1.3719 (18)
S9—C10	1.7127 (16)	S29—C30	1.7122 (16)
C10—C11	1.360 (2)	C30—C31	1.351 (2)
C10—H101	0.941	C30—H301	0.921
C11—C12	1.412 (2)	C31—C32	1.424 (2)
C11—H111	0.927	C31—H311	0.935
C12—H121	0.948	C32—H321	0.938

C2—N1—H12	119.3	C22—N21—H211	121.3
C2—N1—H11	119.5	C22—N21—H212	120.1
H12—N1—H11	119.4	H211—N21—H212	118.3
N1—C2—S3	124.09 (11)	N21—C22—S23	122.70 (11)
N1—C2—N4	116.62 (13)	N21—C22—N24	117.28 (13)
S3—C2—N4	119.28 (10)	S23—C22—N24	120.01 (11)
C2—N4—N5	119.09 (12)	C22—N24—N25	118.70 (12)
C2—N4—H41	118.7	C22—N24—H241	117.3
N5—N4—H41	119.2	N25—N24—H241	122.2
N4—N5—C6	116.53 (12)	N24—N25—C26	117.62 (12)
N5—C6—C7	124.02 (13)	N25—C26—C27	125.81 (13)
N5—C6—C8	116.11 (12)	N25—C26—C28	115.93 (13)
C7—C6—C8	119.87 (12)	C27—C26—C28	118.24 (12)
C6—C7—H71	112.8	C26—C27—H271	112.9
C6—C7—H73	112.7	C26—C27—H273	111.6
H71—C7—H73	107.0	H271—C27—H273	107.4
C6—C7—H72	109.4	C26—C27—H272	110.7
H71—C7—H72	109.4	H271—C27—H272	107.9
H73—C7—H72	105.1	H273—C27—H272	106.0
C6—C8—S9	120.53 (10)	C26—C28—S29	121.16 (10)
C6—C8—C12	128.75 (13)	C26—C28—C32	128.13 (13)
S9—C8—C12	110.66 (11)	S29—C28—C32	110.68 (11)
C8—S9—C10	91.72 (8)	C28—S29—C30	91.80 (8)
S9—C10—C11	112.09 (12)	S29—C30—C31	112.44 (12)
S9—C10—H101	121.9	S29—C30—H301	121.1
C11—C10—H101	126.1	C31—C30—H301	126.4
C10—C11—C12	112.29 (14)	C30—C31—C32	112.12 (14)
C10—C11—H111	124.1	C30—C31—H311	124.5
C12—C11—H111	123.6	C32—C31—H311	123.4
C11—C12—C8	113.24 (13)	C31—C32—C28	112.97 (14)
C11—C12—H121	123.2	C31—C32—H321	126.0
C8—C12—H121	123.5	C28—C32—H321	121.0

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···S3ⁱ	0.83	2.56	3.3609 (16)	162
N21—H212···S3ⁱⁱ	0.83	2.66	3.4691 (16)	167
N24—H241···S23ⁱⁱⁱ	0.85	2.77	3.6128 (14)	174
C7—H72···S23ⁱⁱ	0.98	2.83	3.7236 (16)	153

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

Experimental details

Crystal data
Chemical formula	C₇H₉N₃S₂
M_r	199.31
Crystal system, space group	Triclinic, P1
Temperature (K)	140
a, b, c (Å)	9.0037 (9), 9.7800 (9), 12.1428 (12)
α, β, γ (°)	104.575 (8), 103.345 (8), 108.227 (8)
V (Å³)	925.52 (18)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.52
Crystal size (mm)	0.50 × 0.40 × 0.30

Data collection
Diffractometer	Stoe IPDS diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13175, 5386, 4634
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.723

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.053, 1.00
No. of reflections	5373
No. of parameters	217
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.39

Computer programs: IPDS (Stoe & Cie, 1996), X-RED (Stoe & Cie 1996), SUPERFLIP (Palatinus & Chapuis, 2007), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···S3ⁱ	0.83	2.56	3.3609 (16)	162
N21—H212···S3ⁱⁱ	0.83	2.66	3.4691 (16)	167
N24—H241···S23ⁱⁱⁱ	0.85	2.77	3.6128 (14)	174
C7—H72···S23ⁱⁱ	0.98	2.83	3.7236 (16)	153

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

Acknowledgements

The authors thank the Agence Universitaire de la Francophonie for financial support (AUF-PSCI No. 6314PS804).

References

Arslan, H., Flörke, U. & Külcü, N. (2004). Acta Chim. Slov. 51, 787–792. CAS Google Scholar
Avsar, G., Arslan, H., Haupt, H.-J. & Külcü, N. (2003). Turk. J. Chem. 27, 281–285. CAS Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573 CrossRef CAS Web of Science Google Scholar
Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487. Web of Science CrossRef IUCr Journals Google Scholar
Kusaï, A., Mustayeen, A. K., Magali, A. & Gilles, B. (2009). Polyhedron, 29, 1273–1280. Google Scholar
Palatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786–790. Web of Science CrossRef CAS IUCr Journals Google Scholar
Prince, E. (1982). In Mathematical Techniques in Crystallography and Materials Scienc. New York: Springer-Verlag. Google Scholar
Stoe & Cie (1996). IPDS Software and X-RED. Stoe & Cie, Darmstadt, Germany. Google Scholar
Watkin, D. (1994). Acta Cryst. A50, 411–437. CrossRef CAS Web of Science IUCr Journals Google Scholar
Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England. Google Scholar