6,6,9,9-Tetra­methyl-1,2,5,6,9,9a-hexa­hydro­imidazo­[2,1-d][1,2,5]­di­thia­zepin-1-ium triiodide

The crystal structure of the title compound, C₁₀H₂₀N₂S₂⁺·I₃^-, has been obtained from 294 K single-crystal X-ray diffraction data. The triiodide ion is 3.617 (8) Å from the protonated amine of the heterocycle.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.013 Å
• R factor = 0.041
• wR factor = 0.033
• Data-to-parameter ratio = 12.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_420  Alert C D-H Without Acceptor       N1     -   H1NA              ?

PLAT_420  Alert C D-H Without Acceptor       N1     -   H1NB              ?

PLAT_703  Alert C Torsion Calc    80.3(11), Rep    79.0(10), Dev.      1.18 Sigma
                     C1  -N2  -C4  -C5     1.555   1.555   1.555   1.555

General Notes



ABSTM_02  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
          Tmin and Tmax reported:      0.330     0.768
          Tmin and Tmax expected:      0.258     0.766
          RR =      1.278
          Please check that your absorption correction is appropriate.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 3 Alert Level C = Please check

---

S1. Comment

Growing interest in the potential of radioisotopes ¹⁸⁶Re and ¹⁸⁸Re for tumour-targeting radiotherapy (Nicolini & Mazzi, 1999) has led to the investigation of suitable ligands for complexation. In previous papers (Jackson et al., 1993, 2001; Hambley et al., 1995), we have described the preparation of several lipophilic rhenium–diamino–dithiolate complexes and their crystal structures. We report here the crystal structure of the protonated form of a ligand suitable for complexation with Re isotopes. The ligand is 6,6,9,9-tetramethyl-1,2,5,6,9,9a-hexahydroimidazo[2,1-d][1,2,5]dithiazepine and is reported as the triiodide salt, (I).

The closest contact between the heterocyclic cation and its counter-ion is 3.617 (8) Å, i.e. between I1 and the protonated N1 atom. The Cambridge Structural Database (Allen & Kennard, 1993) has 13 contacts between iodine and a protonated secondary amine, for which the mean distance is 3.649 Å and the shortest is 3.437 Å. In addition to an electrostatic interaction, there may be weak hydrogen bonding between the triiodide and the protonated nitrogen site of the heterocyclic cation.

The disulfide S—S bond of 1.983 (4) Å in the title compound is significantly shorter then the mean length of 2.038 Å obtained from the Cambridge Structural Database. The shortest disulfide bond length in the Cambridge Structural Database is 1.950 Å.

As Fig. 2 indicates, the heterocyclic cation and its counter-ion pack in channels running parallel to the a axis of the unit cell and are separated by the length of that axis.

S2. Experimental

6,6,9,9-Hexamethylhexahydroimidazo[2,1-d][1,2,5]dithiazepine (4.85 g) and methyl iodide (3.64 g, 1.3 molar equivalent, not distilled) in 20 ml of ethyl alcohol were refluxed for 3 h. After cooling, crystals were collected by filtration and washed with diethyl ether. Yield 6.17 g, m.p. 466–468 K.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1995); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1992); program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: TEXSAN; molecular graphics: ORTEPII (Johnson, 1976; Hall et al., 1999); software used to prepare material for publication: TEXSAN.

Figures

	Fig. 1. A view of (I) with displacement ellipsoids shown at the 20% probability level.
	Fig. 2. A depiction of the packing for (I).

(I)

Crystal data

C10H20N2S2^+·I3^−	F(000) = 1140.00
Mr = 613.11	Dx = 2.222 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.7107 Å
a = 8.3334 (9) Å	Cell parameters from 25 reflections
b = 8.080 (2) Å	θ = 8.1–12.1°
c = 27.274 (6) Å	µ = 5.33 mm^−1
β = 93.57 (1)°	T = 294 K
V = 1832.9 (5) Å^3	Prism, brown
Z = 4	0.30 × 0.22 × 0.05 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	1918 reflections with I > 3σ(I)
Radiation source: sealed tube	Rint = 0.024
Graphite monochromator	θmax = 25.0°, θmin = 2.5°
ω–θ scans	h = −9→9
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	k = −1→9
Tmin = 0.330, Tmax = 0.768	l = −1→32
4236 measured reflections	3 standard reflections every 100 reflections
3218 independent reflections	intensity decay: 2.6%

Refinement

Refinement on F	0 restraints
Least-squares matrix: full	0 constraints
R[F^2 > 2σ(F^2)] = 0.041	H-atom parameters not refined
wR(F^2) = 0.033	Weighting scheme based on measured s.u.'s w = 1/[σ^2(Fo) + 0.00002|Fo|^2]
S = 1.60	(Δ/σ)max = 0.001
1918 reflections	Δρmax = 0.82 e Å^−3
154 parameters	Δρmin = −0.86 e Å^−3

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

	x	y	z	Uiso*/Ueq
I1	−0.11874 (9)	0.2624 (1)	0.47403 (3)	0.0638 (3)
I2	0.01726 (9)	0.39447 (9)	0.38661 (3)	0.0540 (2)
I3	0.1433 (1)	0.5323 (1)	0.29796 (3)	0.0779 (3)
S1	0.4436 (4)	0.0882 (4)	0.3916 (1)	0.069 (1)
S2	0.3792 (3)	−0.1334 (4)	0.4146 (1)	0.075 (1)
N1	0.8474 (10)	−0.1786 (10)	0.4202 (3)	0.050 (3)
N2	0.6997 (9)	−0.1354 (10)	0.3544 (3)	0.043 (3)
C1	0.702 (1)	−0.185 (1)	0.4010 (4)	0.038 (3)
C2	0.965 (1)	−0.122 (1)	0.3877 (4)	0.050 (3)
C3	0.866 (1)	−0.091 (1)	0.3409 (4)	0.063 (4)
C4	0.561 (1)	−0.110 (1)	0.3210 (4)	0.047 (3)
C5	0.473 (1)	0.052 (1)	0.3264 (4)	0.045 (3)
C6	0.564 (1)	−0.251 (1)	0.4288 (4)	0.045 (3)
C7	0.526 (1)	−0.427 (1)	0.4110 (5)	0.088 (5)
C8	0.607 (1)	−0.246 (2)	0.4835 (5)	0.073 (4)
C9	0.570 (1)	0.202 (1)	0.3125 (5)	0.071 (4)
C10	0.313 (1)	0.039 (1)	0.2948 (5)	0.079 (5)
H1Na	0.8770	−0.2866	0.4312	0.060*
H1Nb	0.8491	−0.1057	0.4476	0.060*
H2a	1.0464	−0.2061	0.3833	0.060*
H2b	1.0171	−0.0212	0.3998	0.060*
H3a	0.9004	−0.1618	0.3146	0.076*
H3b	0.8724	0.0235	0.3309	0.076*
H4a	0.4862	−0.1995	0.3258	0.057*
H4b	0.5969	−0.1149	0.2878	0.057*
H7b	0.4142	−0.4532	0.4162	0.105*
H7c	0.5434	−0.4359	0.3763	0.105*
H7a	0.5951	−0.5052	0.4292	0.105*
H8b	0.6918	−0.3247	0.4917	0.088*
H8c	0.5128	−0.2738	0.5011	0.088*
H8a	0.6429	−0.1354	0.4927	0.088*
H9b	0.5220	0.3008	0.3252	0.085*
H9c	0.6792	0.1905	0.3263	0.085*
H9a	0.5699	0.2090	0.2770	0.085*
H10b	0.2460	0.1339	0.3012	0.095*
H10c	0.2572	−0.0617	0.3031	0.095*
H10a	0.3349	0.0368	0.2603	0.095*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0557 (5)	0.0717 (6)	0.0633 (6)	−0.0001 (4)	−0.0016 (4)	0.0127 (5)
I2	0.0532 (4)	0.0457 (4)	0.0628 (5)	0.0049 (4)	0.0029 (4)	−0.0048 (4)
I3	0.1032 (7)	0.0692 (6)	0.0640 (6)	0.0076 (5)	0.0267 (6)	−0.0036 (5)
S1	0.075 (2)	0.066 (2)	0.067 (2)	0.026 (2)	0.007 (2)	−0.009 (2)
S2	0.040 (2)	0.101 (3)	0.088 (3)	0.017 (2)	0.018 (2)	0.029 (2)
N1	0.043 (5)	0.054 (6)	0.054 (6)	0.002 (5)	−0.004 (5)	−0.007 (5)
N2	0.039 (5)	0.048 (6)	0.041 (6)	0.012 (4)	0.000 (5)	0.001 (5)
C1	0.031 (6)	0.045 (6)	0.036 (7)	0.011 (5)	−0.010 (5)	−0.011 (6)
C2	0.039 (6)	0.044 (7)	0.068 (8)	0.003 (5)	0.015 (6)	−0.005 (6)
C3	0.042 (6)	0.085 (9)	0.065 (9)	0.012 (7)	0.016 (6)	0.019 (8)
C4	0.042 (6)	0.064 (7)	0.034 (6)	0.008 (6)	−0.012 (5)	−0.004 (6)
C5	0.042 (6)	0.045 (7)	0.048 (7)	0.012 (5)	0.000 (6)	−0.007 (6)
C6	0.032 (6)	0.056 (7)	0.049 (7)	0.003 (5)	0.005 (5)	0.009 (6)
C7	0.079 (9)	0.067 (10)	0.12 (1)	−0.025 (7)	−0.012 (9)	0.021 (9)
C8	0.052 (7)	0.11 (1)	0.059 (9)	−0.005 (7)	0.015 (7)	0.015 (9)
C9	0.071 (8)	0.058 (8)	0.083 (10)	0.010 (7)	−0.011 (7)	0.015 (7)
C10	0.052 (7)	0.071 (9)	0.11 (1)	0.012 (7)	−0.006 (8)	0.000 (8)

Geometric parameters (Å, º)

I1—I2	2.906 (1)	C4—H4a	0.97
I2—I3	2.916 (1)	C4—H4b	0.97
S1—S2	1.983 (4)	C5—C9	1.52 (1)
S1—C5	1.83 (1)	C5—C10	1.54 (1)
S2—C6	1.830 (10)	C6—C7	1.53 (1)
N1—C1	1.29 (1)	C6—C8	1.51 (1)
N1—C2	1.44 (1)	C7—H7b	0.97
N1—H1Na	0.95	C7—H7c	0.97
N1—H1Nb	0.95	C7—H7a	0.97
N2—C1	1.33 (1)	C8—H8b	0.97
N2—C3	1.50 (1)	C8—H8c	0.97
N2—C4	1.44 (1)	C8—H8a	0.97
C1—C6	1.51 (1)	C9—H9b	0.97
C2—C3	1.50 (1)	C9—H9c	0.97
C2—H2a	0.97	C9—H9a	0.97
C2—H2b	0.97	C10—H10b	0.97
C3—H3a	0.97	C10—H10c	0.97
C3—H3b	0.97	C10—H10a	0.97
C4—C5	1.51 (1)
S2···C2^i	3.481 (10)	I1···S2^iii	3.981 (3)
I1···N1^ii	3.617 (8)	I2···N1^iv	3.861 (8)
I1···N1^i	3.858 (8)	I2···C2^iv	3.931 (8)
I1···C2^i	3.985 (9)	I3···C3^v	3.912 (10)
I1—I2—I3	178.05 (4)	S1—C5—C10	113.0 (8)
S2—S1—C5	102.5 (4)	C4—C5—C9	113.1 (8)
S1—S2—C6	107.2 (4)	C4—C5—C10	107.4 (8)
C1—N1—C2	115.0 (9)	C9—C5—C10	111.6 (9)
C1—N1—H1Na	108.1	S2—C6—C1	111.3 (7)
C1—N1—H1Nb	108.1	S2—C6—C7	105.2 (7)
C2—N1—H1Na	108.1	S2—C6—C8	109.7 (8)
C2—N1—H1Nb	108.1	C1—C6—C7	108.7 (9)
H1Na—N1—H1Nb	109.5	C1—C6—C8	110.1 (9)
C1—N2—C3	110.4 (9)	C7—C6—C8	111.8 (10)
C1—N2—C4	127.6 (9)	C6—C7—H7b	109.5
C3—N2—C4	121.8 (9)	C6—C7—H7c	109.5
N1—C1—N2	109.4 (9)	C6—C7—H7a	109.5
N1—C1—C6	122.2 (10)	H7b—C7—H7c	109.5
N2—C1—C6	128.3 (9)	H7b—C7—H7a	109.4
N1—C2—C3	102.5 (8)	H7c—C7—H7a	109.4
N1—C2—H2a	111.2	C6—C8—H8b	109.5
N1—C2—H2b	111.2	C6—C8—H8c	109.5
C3—C2—H2a	111.2	C6—C8—H8a	109.5
C3—C2—H2b	111.2	H8b—C8—H8c	109.5
H2a—C2—H2b	109.5	H8b—C8—H8a	109.4
N2—C3—C2	102.7 (8)	H8c—C8—H8a	109.4
N2—C3—H3a	111.1	C5—C9—H9b	109.5
N2—C3—H3b	111.2	C5—C9—H9c	109.5
C2—C3—H3a	111.1	C5—C9—H9a	109.5
C2—C3—H3b	111.1	H9b—C9—H9c	109.5
H3a—C3—H3b	109.5	H9b—C9—H9a	109.5
N2—C4—C5	116.0 (9)	H9c—C9—H9a	109.5
N2—C4—H4a	107.8	C5—C10—H10b	109.4
N2—C4—H4b	107.8	C5—C10—H10c	109.4
C5—C4—H4a	107.8	C5—C10—H10a	109.5
C5—C4—H4b	107.8	H10b—C10—H10c	109.4
H4a—C4—H4b	109.5	H10b—C10—H10a	109.5
S1—C5—C4	109.2 (7)	H10c—C10—H10a	109.5
S1—C5—C9	102.6 (8)
S1—S2—C6—C1	−23.5 (8)	N2—C1—N1—C2	0 (1)
S1—S2—C6—C7	−141.0 (7)	N2—C1—C6—C7	73 (1)
S1—S2—C6—C8	98.6 (8)	N2—C1—C6—C8	−163 (1)
S1—C5—C4—N2	−46 (1)	N2—C4—C5—C9	67 (1)
S2—S1—C5—C4	−42.9 (7)	N2—C4—C5—C10	−169.1 (9)
S2—S1—C5—C9	−163.1 (6)	C1—N1—C2—C3	0 (1)
S2—S1—C5—C10	76.6 (8)	C1—N2—C3—C2	0 (1)
S2—C6—C1—N1	142.7 (8)	C1—N2—C4—C5	79 (1)
S2—C6—C1—N2	−42 (1)	C2—N1—C1—C6	176.1 (9)
N1—C1—N2—C3	0 (1)	C2—C3—N2—C4	174.4 (9)
N1—C1—N2—C4	−174.2 (9)	C3—N2—C1—C6	−175.4 (9)
N1—C1—C6—C7	−101 (1)	C3—N2—C4—C5	−94 (1)
N1—C1—C6—C8	20 (1)	C4—N2—C1—C6	10 (1)
N1—C2—C3—N2	0 (1)	C5—S1—S2—C6	83.7 (5)

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