2,3,4,5-Tetra­hydro-1,3-thia­zepino­[3,2-a][1,3]­benz­imidazole

The structure of the title compound, C₁₁H₁₂N₂S, established by an X-ray crystallographic study, shows that the mol­ecule is composed of three cycles: bicyclic benz­imidazole and the thia­zepine ring which is bent.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.001 Å
• R factor = 0.052
• wR factor = 0.091
• Data-to-parameter ratio = 11.6

checkCIF results

No syntax errors found



ADDSYM reports no extra symmetry


 Alert Level B:



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           25.16
         From the CIF: _reflns_number_total               1573
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         1795
         Completeness (_total/calc)             87.63%
          Alert B: < 90% complete (theta max?)


 Alert Level C:



PLAT_732  Alert C Angle   Calc  100.35(10), Rep   100.36(4) ....       2.50 s.u-Ratio
                     C2   -S1   -C14     1.555   1.555   1.555


 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

Thiazepinobenzimidazole derivatives constituted an interesting series of heterocyclic compounds, particularly for their biological activities (Nawrocka & Zimecki, 1998; Taniguchi et al., 1993; Kuehler et al., 1998; Tabata et al., 1995; Pedini et al., 1994; Piras et al., 1993; Nukaya et al., 1991). We report here the preparation and crystal structure determination of the title compound, (I).

Selected bond distances and angles are given in Table 1. The molecule is composed of three cycles, i.e. the benzimidazole system and a thiazepine ring. The benzimidazole system is planar (r.m.s. deviation: 0.0136 Å) and the thiazepine seven-membered ring is composed of three planar fragments: S1/C2/N10/C11, which is coplanar with the benzimidazole and at an angle of 118.9 (5)° to the S1/C11/C12/C14 fragment, which is, in turn, at an angle of 121.1 (4)° to the C12/C13/C14 triangle. According to Cremer & Pople (1975), the seven-membered ring conformation can be described on the basis of the total puckering amplitude Q_T = 0.872 (1) Å and the asymetry parameters that are indicative of a local pseudo-twofold axis running along C13 and the midpoint of the C2—N10 bond.

S2. Experimental

A solution of benzimidazole-2-thione (0.007 mol) and 1,4-dibromobutane (0.014 mol) in 50 ml of saturated aqueous solution of sodium bicarbonate and 50 ml of 2-propanol, was heated under reflux for 1 h. After isolation of 1,4-bis(2-mercaptobenzimidazolyl)butane, the reaction product was obtained by removing the 2-propanol and then extracting the residue with chloroform. Removal of chloroform gave the title compound, yield: 40%, m.p. 403–407 K. Crystals were obtained by evaporation of an ethanol solution at room temperature.

Computing details

Data collection: KappaCCD Reference Manual (Nonius, 1998); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: maXus (Mackay et al., 1999); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: maXus.

Figures

Fig. 1. Perspective view of the title molecule showing the labelling of the atoms, with displacement ellipsoids at the 50% probability level.

(global)

Crystal data

C11H12N2S	Z = 2
Mr = 204.29	F(000) = 186
Triclinic, P1	Dx = 1.352 Mg m^−3
a = 6.6159 (7) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.507 (1) Å	Cell parameters from 2941 reflections
c = 9.468 (1) Å	θ = 1–25.1°
α = 88.57 (6)°	µ = 0.28 mm^−1
β = 72.53 (9)°	T = 298 K
γ = 80.89 (4)°	Prism, colourless
V = 501.7 (1) Å^3	0.45 × 0.30 × 0.15 mm

Data collection

KappaCCD diffractometer	Rint = 0.037
Radiation source: fine-focus sealed tube	θmax = 25.2°
ϕ scans	h = −7→0
1581 measured reflections	k = −10→10
1573 independent reflections	l = −11→11
1476 reflections with I > 3σ(I)

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: geom, diff
R[F^2 > 2σ(F^2)] = 0.052	H-atom parameters constrained
wR(F^2) = 0.091	Weighting scheme based on measured s.u.'s w = 1/[s^2(Fo^2) + 0.03Fo^2]
S = 1.01	(Δ/σ)max = 0.028
1476 reflections	Δρmax = 0.15 e Å^−3
127 parameters	Δρmin = −0.17 e Å^−3
Primary atom site location: structure-invariant direct methods

Special details

Geometry. All standard uncertainties (except dihedral angles between l.s. planes) are estimated using the full covariance matrix. The standard uncertainties in cell dimensions are are used in calculating the standard uncertainties of bond distances, angles and torsion angles. Angles between l.s. planes have standard uncertainties calculated from atomic positional standard uncertainties; the errors in cell dimensions are not used in this case.

Refinement. Refinement on F².

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

	x	y	z	Uiso*/Ueq
S1	1.24260 (3)	0.22405 (2)	0.79212 (2)	0.04973 (9)
N3	1.14387 (11)	0.18114 (7)	1.08865 (7)	0.0457 (3)
N10	0.85830 (10)	0.21690 (6)	1.00161 (6)	0.0403 (3)
C2	1.07490 (13)	0.20699 (7)	0.97136 (8)	0.0415 (3)
C4	0.95771 (13)	0.17408 (7)	1.20354 (8)	0.0420 (3)
C5	0.93098 (15)	0.15167 (9)	1.35532 (9)	0.0521 (4)
C6	0.72519 (17)	0.15675 (10)	1.44690 (9)	0.0569 (4)
C7	0.54882 (15)	0.17977 (9)	1.39352 (9)	0.0547 (4)
C8	0.56951 (13)	0.20047 (8)	1.24454 (9)	0.0475 (4)
C9	0.77886 (12)	0.19723 (7)	1.15226 (7)	0.0396 (3)
C11	0.73328 (14)	0.24006 (8)	0.89663 (8)	0.0480 (4)
C12	0.72632 (15)	0.40543 (9)	0.83061 (9)	0.0525 (4)
C13	0.92451 (16)	0.43009 (9)	0.70569 (9)	0.0567 (4)
C14	1.12830 (15)	0.42160 (9)	0.74748 (9)	0.0538 (4)
H5	1.04877	0.13307	1.39552	0.07072*
H6	0.69849	0.14565	1.55169	0.07505*
H7	0.40582	0.18047	1.45991	0.07157*
H8	0.45061	0.21586	1.20334	0.06535*
H11A	0.79497	0.16456	0.81563	0.06715*
H11B	0.58697	0.22456	0.94573	0.06715*
H12A	0.70261	0.47913	0.91070	0.07075*
H12B	0.60001	0.42303	0.79550	0.07075*
H13A	0.88790	0.53358	0.67129	0.07390*
H13B	0.99080	0.34858	0.61179	0.07390*
H14A	1.24482	0.44740	0.66246	0.07142*
H14B	1.10546	0.49409	0.84231	0.07142*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.04547 (14)	0.04663 (12)	0.04777 (12)	−0.00441 (8)	−0.00527 (9)	0.00188 (8)
N3	0.0418 (4)	0.0401 (3)	0.0509 (4)	−0.0051 (2)	−0.0195 (3)	0.0039 (2)
N10	0.0370 (4)	0.0380 (3)	0.0422 (3)	−0.0077 (2)	−0.0151 (3)	0.0069 (2)
C2	0.0398 (4)	0.0332 (3)	0.0463 (4)	−0.0064 (3)	−0.0125 (3)	0.0044 (3)
C4	0.0449 (5)	0.0313 (3)	0.0454 (4)	−0.0061 (3)	−0.0173 (3)	0.0036 (3)
C5	0.0605 (6)	0.0438 (4)	0.0487 (4)	−0.0104 (3)	−0.0262 (4)	0.0063 (3)
C6	0.0699 (7)	0.0527 (4)	0.0415 (4)	−0.0124 (4)	−0.0170 (4)	0.0054 (3)
C7	0.0544 (6)	0.0527 (4)	0.0477 (4)	−0.0114 (4)	−0.0060 (4)	0.0065 (3)
C8	0.0423 (5)	0.0428 (4)	0.0512 (4)	−0.0068 (3)	−0.0132 (3)	0.0077 (3)
C9	0.0420 (4)	0.0301 (3)	0.0419 (4)	−0.0061 (3)	−0.0139 (3)	0.0047 (3)
C11	0.0505 (5)	0.0446 (4)	0.0465 (4)	−0.0130 (3)	−0.0234 (3)	0.0103 (3)
C12	0.0533 (5)	0.0454 (4)	0.0535 (4)	−0.0066 (3)	−0.0212 (4)	0.0120 (3)
C13	0.0671 (6)	0.0459 (4)	0.0500 (4)	−0.0113 (4)	−0.0185 (4)	0.0130 (3)
C14	0.0579 (6)	0.0438 (4)	0.0519 (4)	−0.0162 (3)	−0.0104 (4)	0.0087 (3)

Geometric parameters (Å, º)

S1—C2	1.7437 (7)	C4—C9	1.3932 (11)
S1—C14	1.8245 (8)	C5—C6	1.3718 (13)
N3—C2	1.3228 (10)	C6—C7	1.3900 (13)
N3—C4	1.3855 (10)	C7—C8	1.3851 (11)
N10—C2	1.3635 (11)	C8—C9	1.3947 (11)
N10—C9	1.3801 (8)	C11—C12	1.5248 (10)
N10—C11	1.4640 (9)	C12—C13	1.5185 (12)
C4—C5	1.4062 (10)	C13—C14	1.5058 (14)
C2—S1—C14	100.36 (4)	C4—C5—C6	117.23 (8)
C2—N3—C4	103.52 (7)	C5—C6—C7	122.17 (7)
C2—N10—C9	106.09 (6)	C6—C7—C8	122.11 (8)
C2—N10—C11	127.57 (6)	C7—C8—C9	115.44 (7)
C9—N10—C11	126.32 (6)	N10—C9—C4	105.37 (6)
S1—C2—N3	123.93 (6)	N10—C9—C8	131.31 (7)
S1—C2—N10	121.98 (6)	C4—C9—C8	123.32 (7)
N3—C2—N10	114.08 (6)	N10—C11—C12	113.27 (6)
N3—C4—C5	129.34 (8)	C11—C12—C13	115.32 (7)
N3—C4—C9	110.93 (6)	C12—C13—C14	115.82 (7)
C5—C4—C9	119.72 (8)	S1—C14—C13	115.53 (6)