6-Amino-4-iminio-4H-1,3,5-di­thia­zole iodide

The structure of the title compound, C₃H₆IN₃S₂, comprises a puckered ring that associates to the I⁻ anion via N—H...I interactions. In the asymmetric unit, two I⁻ anions reside on special positions (twofold rotation axes) equivalent to one complete anion per cation. The cationic charge is delocalized between the two amines, as suggested by the similar bond lengths, across the heterocyclic N atom, between these two groups.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](N-C) = 0.005 Å
• R factor = 0.044
• wR factor = 0.109
• Data-to-parameter ratio = 18.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_352  Alert C Short N-H Bond (0.87A)     N(41)  -   H(41)  =       0.74 Ang.

PLAT_420  Alert C D-H without acceptor       N(41)  -   H(41)             ?


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

Compound (I) is marketed as 4,6-diimino-1,3,5-dithiazolidine hydrogen iodide (Fig. 2a) whereas elucidation of the crystal structure reveals a delocalized cation with an I^- anion. The two resonant forms, from which the compound has been named, are shown in Fig 2(b). Bond distances for the atoms between the two amines are listed in Table 2.

S2. Experimental

The title compound, (I), was prepared by Spa Contract Synthesis.

S3. Refinement

The four amine H atoms were located on difference syntheses and both displacement and positional parameters were refined, while the CH₂ H atoms were included in the refinement at calculated positions as riding models, with C—H set to 0.99 Å. The largest difference map features were close to the I^- anions.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular configuration and atom-numbering scheme for (I), showing 50% probability displacement ellipsoids.
	Fig. 2. The structures of (a) the marketed configuration and (b) the resonant forms of (I).

4-Amino-6-imidium-1,3,5-dithiazol-4-ene iodide

Crystal data

C3H6N3S2^+·I^−	Dx = 2.267 Mg m^−3
Mr = 275.13	Melting point: ? K K
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.050 (2) Å	Cell parameters from 5412 reflections
b = 18.964 (4) Å	θ = 1.0–27.5°
c = 8.1307 (16) Å	µ = 4.41 mm^−1
β = 108.87 (3)°	T = 150 K
V = 1612.2 (6) Å^3	Plate, colourless
Z = 8	0.35 × 0.20 × 0.08 mm
F(000) = 1040

Data collection

Enraf Nonius KappaCCD area-detector diffractometer	1818 independent reflections
Radiation source: Enraf Nonius FR591 rotating anode	1726 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.074
Detector resolution: 9.091 pixels mm^-1	θmax = 27.5°, θmin = 2.1°
ϕ and ω scans	h = −14→13
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −24→24
Tmin = 0.307, Tmax = 0.719	l = −10→10
7382 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.044	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.109	w = 1/[σ^2(Fo^2) + (0.085P)^2 + 0.3966P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1818 reflections	Δρmax = 2.79 e Å^−3
100 parameters	Δρmin = −2.70 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0043 (5)

Special details

Experimental. PLEASE NOTE cell_measurement_ fields are not relevant to area detector data, the entire data set is used to refine the cell, which is indexed from all observed reflections in a 10 degree phi range.

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

	x	y	z	Uiso*/Ueq
I1	0.5000	0.127771 (16)	0.2500	0.01778 (18)
I2	0.0000	0.10986 (2)	0.2500	0.01743 (18)
S1	0.17012 (7)	0.19044 (5)	0.82791 (10)	0.0177 (2)
C2	0.3142 (3)	0.22011 (17)	0.7927 (4)	0.0158 (6)
H21	0.3122	0.2722	0.7829	0.020*
H22	0.3885	0.2072	0.8946	0.020*
S3	0.33490 (7)	0.18302 (5)	0.60085 (10)	0.0157 (2)
C4	0.3257 (3)	0.09344 (18)	0.6500 (4)	0.0136 (6)
N41	0.3741 (3)	0.05065 (16)	0.5627 (3)	0.0194 (6)
H41	0.371 (3)	0.012 (2)	0.576 (5)	0.016 (9)*
H42	0.415 (4)	0.066 (3)	0.488 (5)	0.041 (12)*
N5	0.2748 (2)	0.06531 (14)	0.7617 (3)	0.0157 (5)
C6	0.2010 (3)	0.09970 (17)	0.8345 (4)	0.0149 (6)
N61	0.1375 (3)	0.06203 (17)	0.9149 (4)	0.0194 (6)
H61	0.131 (4)	0.018 (2)	0.897 (6)	0.042 (12)*
H62	0.098 (4)	0.080 (3)	0.980 (5)	0.036 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0276 (3)	0.0190 (3)	0.0091 (2)	0.000	0.00924 (17)	0.000
I2	0.0201 (2)	0.0194 (3)	0.0158 (2)	0.000	0.00999 (15)	0.000
S1	0.0187 (4)	0.0180 (4)	0.0190 (4)	0.0000 (3)	0.0095 (3)	−0.0039 (3)
C2	0.0164 (13)	0.0184 (14)	0.0135 (13)	−0.0035 (11)	0.0062 (10)	−0.0004 (11)
S3	0.0234 (4)	0.0159 (4)	0.0092 (4)	−0.0006 (3)	0.0072 (3)	0.0014 (3)
C4	0.0129 (13)	0.0168 (15)	0.0098 (13)	0.0021 (11)	0.0017 (10)	0.0008 (11)
N41	0.0274 (14)	0.0195 (15)	0.0152 (12)	0.0003 (12)	0.0123 (10)	0.0001 (11)
N5	0.0194 (10)	0.0170 (12)	0.0127 (11)	−0.0008 (11)	0.0078 (8)	0.0016 (10)
C6	0.0151 (13)	0.0174 (16)	0.0123 (13)	−0.0007 (11)	0.0046 (10)	−0.0011 (12)
N61	0.0226 (13)	0.0211 (14)	0.0203 (13)	−0.0055 (12)	0.0150 (11)	−0.0030 (12)

Geometric parameters (Å, º)

S1—C6	1.752 (3)	C4—N5	1.325 (4)
S1—C2	1.797 (3)	N41—H41	0.74 (4)
C2—S3	1.792 (3)	N41—H42	0.91 (4)
C2—H21	0.99	N5—C6	1.325 (4)
C2—H22	0.99	C6—N61	1.314 (4)
S3—C4	1.756 (4)	N61—H61	0.85 (5)
C4—N41	1.302 (4)	N61—H62	0.86 (4)
C6—S1—C2	97.97 (15)	C4—N41—H41	119 (3)
S3—C2—S1	112.62 (15)	C4—N41—H42	123 (3)
S3—C2—H21	109.1	H41—N41—H42	117 (4)
S1—C2—H21	109.1	C4—N5—C6	124.6 (3)
S3—C2—H22	109.1	N61—C6—N5	117.4 (3)
S1—C2—H22	109.1	N61—C6—S1	114.8 (2)
H21—C2—H22	107.8	N5—C6—S1	127.7 (2)
C4—S3—C2	98.54 (15)	C6—N61—H61	118 (3)
N41—C4—N5	117.6 (3)	C6—N61—H62	123 (3)
N41—C4—S3	114.5 (2)	H61—N61—H62	118 (4)
N5—C4—S3	127.9 (3)
C6—S1—C2—S3	57.53 (18)	S3—C4—N5—C6	12.7 (4)
S1—C2—S3—C4	−55.58 (18)	C4—N5—C6—N61	166.9 (3)
C2—S3—C4—N41	−160.5 (2)	C4—N5—C6—S1	−9.6 (4)
C2—S3—C4—N5	20.3 (3)	C2—S1—C6—N61	158.1 (2)
N41—C4—N5—C6	−166.4 (3)	C2—S1—C6—N5	−25.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N41—H41···I1^i	0.74 (4)	3.13 (4)	3.786 (3)	150 (3)
N41—H42···I1	0.91 (4)	2.68 (4)	3.581 (3)	169 (4)
N61—H61···I2^ii	0.85 (5)	2.88 (5)	3.663 (3)	155 (4)
N61—H62···I2^iii	0.86 (4)	2.80 (4)	3.638 (3)	165 (4)

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