3,14-Diselena-4,5,12,13-tetra­aza­tri­cyclo­[9.3.0.0^2,6]tetra­deca-1(11),2(6),4,12-tetra­ene

A third isomer of cyclooctenobis-1,2,3-selenadiazoles is reported. The mol­ecule is located on a twofold rotation axis and the eight-membered ring adopts a twist-chair conformation with planar heterocycles.

Abstract

The crystal structure of the third isomer of cyclooctenobis-1,2,3-selenadiazoles, C₈H₈N₄Se₂, is reported. The mol­ecule is located on a twofold rotation axis. The eight-membered ring adopts a twist-chair conformation with planar heterocycles. C—H⋯N hy­dro­gen bonds connect the mol­ecules into layers parallel to (101).

Structure description

The title com­pound, C₈H₈N₄Se₂ (Fig. 1 ▸), is the third isomer in the series of cyclo­octenobis-1,2,3-selena­diazo­les (Detert & Schollmeyer, 2020 ▸; Schollmeyer & Detert, 2025 ▸). These were prepared as part of a project on medium-sized cyclo­alkynes with functional and sterically demanding groups (Bissinger et al., 1988 ▸; Detert et al., 1994 ▸; Detert & Meier, 1997 ▸). Bis-1,2,3-selena­diazo­les are anti­microbial agents (Al-Smadi et al., 2008 ▸) and important sources for medium-sized cyclo­alkadiynes (Gleiter et al., 1988 ▸; Morales & Fronczek, 1994 ▸). The mol­ecule is C₂-symmetric, having the eight-membered ring in a nearly twist-chair conformation with staggered C—H bonds. Both selena­diazole rings are planar within 0.02 (6) Å at atom C5 and the torsion angle between the heterocycles is 55.5 (3)°. This is significantly larger than the torsion angle [−43.5 (11)°] between the selena­diazole rings in the isomeric mol­ecule with an inverted orientation of the annulated heterocycles (Detert & Schollmeyer, 2020 ▸), probably due to the large atomic radii of the vicinal Se atoms in the title com­pound. The unit cell contains four mol­ecules connected via four hy­dro­gen bonds [C7—H7b⋯N2ⁱ; symmetry code: (i) −x, y + , −z + ]. The hy­dro­gen bonds (Table 1 ▸, Fig. 2 ▸) connect the mol­ecules to form layers parallel to (01).

Figure 1.

The mol­ecular structure of the title com­pound. Displacement ellipsoids are drawn at the 50% probability level.

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7B⋯N2i	0.99	2.61	3.466 (9)	144

Symmetry code: (i) .

Figure 2.

Part of the packing diagram, viewed along the c-axis direction.

Synthesis and crystallization

The title com­pound appeared in the synthesis of its homo-conjugated isomer (Schollmeyer & Detert, 2025 ▸) from 1,4-cyclo­octa­nedione bis­semicarbazone and selenium dioxide in 1,4-dioxane in 12% yield. Recrystallization from a solution in chloro­form/ligroin gave brownish crystals (m.p. 393 K). IR (KBr): 2900, 2840, 1515, 1460, 1440, 1430, 1340, 1295, 1275, 1250, 1215, 945, 880, 850 cm⁻¹. ¹H NMR (400 MHz, CDCl₃): δ 3.20 (bs, 4H), 1.90 (bs, 4H); ¹³C NMR (100 MHz, CDCl₃): δ 158.8, 144.9 (C-1,2,7,10), 27.4, 25.1 (C-6,7,8,9); ⁷⁷Se NMR (73 MHz, CDCl₃, SeO₂/D₂O as reference): δ 295.9; ¹⁵N NMR (40,5 MHz, CDCl₃, HC₃NO₂ as reference = 0): δ 93.9, 93.1; UV (EtOH, λ, logɛ): 207 (3.85), 220 (3.86), 261 (3.57), 302 (sh, 3.33), 339 nm (sh, 3.12); MS (FD): 290 (M – N₂^+.).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms were placed at calculated positions and refined in the riding-model approximation, with C—H = 0.99 Å and U_iso(H) = 1.2U_eq(C).

Table 2. Experimental details.

Crystal data
Chemical formula	C8H8N4Se2
M r	318.10
Crystal system, space group	Monoclinic, I2/a
Temperature (K)	120
a, b, c (Å)	11.746 (2), 8.1617 (10), 10.0922 (15)
β (°)	97.121 (14)
V (Å3)	960.1 (3)
Z	4
Radiation type	Mo Kα
μ (mm−1)	7.66
Crystal size (mm)	0.48 × 0.09 × 0.04
Data collection
Diffractometer	STOE IPDS 2T
Absorption correction	Integration
Tmin, Tmax	0.468, 0.893
No. of measured, independent and observed [I > 2σ(I)] reflections	2481, 1144, 930
R int	0.037
(sin θ/λ)max (Å−1)	0.663
Refinement
R[F2 > 2σ(F2)], wR(F2), S	0.056, 0.148, 1.10
No. of reflections	1144
No. of parameters	64
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	1.04, −1.75

Computer programs: X-AREAWinXpose (Stoe & Cie, 2020 ▸), X-AREARecipe (Stoe & Cie, 2020 ▸), X-AREAIntegrate (Stoe & Cie, 2020 ▸), SHELXT2014 (Sheldrick, 2015a ▸), SHELXL2019 (Sheldrick, 2015b ▸) and PLATON (Spek, 2020 ▸).

Supplementary Material

CCDC reference: 2524974

Additional supporting information: crystallographic information; 3D view; checkCIF report

full crystallographic data

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Crystal data

C8H8N4Se2	F(000) = 608
Mr = 318.10	Dx = 2.201 Mg m−3
Monoclinic, I2/a	Mo Kα radiation, λ = 0.71073 Å
a = 11.746 (2) Å	Cell parameters from 5444 reflections
b = 8.1617 (10) Å	θ = 3.1–28.2°
c = 10.0922 (15) Å	µ = 7.66 mm−1
β = 97.121 (14)°	T = 120 K
V = 960.1 (3) Å3	Plate, colorless
Z = 4	0.48 × 0.09 × 0.04 mm

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Data collection

STOE IPDS 2T diffractometer	930 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1	Rint = 0.037
rotation method, ω scans	θmax = 28.1°, θmin = 3.1°
Absorption correction: integration	h = −15→13
Tmin = 0.468, Tmax = 0.893	k = −10→10
2481 measured reflections	l = −13→13
1144 independent reflections

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Refinement

Refinement on F2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.056	H-atom parameters constrained
wR(F2) = 0.148	w = 1/[σ2(Fo2) + (0.0748P)2 + 11.7676P] where P = (Fo2 + 2Fc2)/3
S = 1.10	(Δ/σ)max < 0.001
1144 reflections	Δρmax = 1.04 e Å−3
64 parameters	Δρmin = −1.75 e Å−3
0 restraints

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Se1	0.14172 (6)	0.61729 (7)	0.33965 (6)	0.0274 (3)
N2	0.0080 (5)	0.4890 (7)	0.3007 (5)	0.0291 (12)
N3	0.0157 (5)	0.3578 (7)	0.3698 (5)	0.0289 (12)
C4	0.1149 (6)	0.3307 (8)	0.4573 (6)	0.0259 (13)
C5	0.1943 (5)	0.4546 (8)	0.4581 (6)	0.0269 (13)
C6	0.1228 (6)	0.1830 (8)	0.5420 (6)	0.0254 (12)
H6A	0.044169	0.148577	0.555241	0.031*
H6B	0.163678	0.211823	0.630606	0.031*
C7	0.1843 (6)	0.0368 (8)	0.4861 (6)	0.0284 (13)
H7A	0.155565	−0.065021	0.523630	0.034*
H7B	0.162450	0.033262	0.388198	0.034*

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Se1	0.0327 (4)	0.0269 (4)	0.0241 (4)	0.0027 (3)	0.0096 (3)	0.0013 (2)
N2	0.031 (3)	0.033 (3)	0.024 (2)	0.001 (2)	0.007 (2)	−0.001 (2)
N3	0.030 (3)	0.031 (3)	0.028 (3)	0.003 (2)	0.011 (2)	0.000 (2)
C4	0.027 (3)	0.027 (3)	0.026 (3)	−0.003 (3)	0.012 (2)	−0.003 (2)
C5	0.027 (3)	0.029 (3)	0.027 (3)	−0.001 (3)	0.011 (2)	−0.006 (2)
C6	0.029 (3)	0.024 (3)	0.025 (3)	−0.006 (3)	0.010 (2)	−0.002 (2)
C7	0.034 (3)	0.027 (3)	0.026 (3)	0.001 (3)	0.008 (3)	0.002 (3)

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Geometric parameters (Å, º)

Se1—C5	1.841 (7)	C6—C7	1.538 (9)
Se1—N2	1.888 (6)	C6—H6A	0.9900
N2—N3	1.275 (8)	C6—H6B	0.9900
N3—C4	1.390 (9)	C7—C7i	1.534 (13)
C4—C5	1.375 (9)	C7—H7A	0.9900
C4—C6	1.474 (9)	C7—H7B	0.9900
C5—C5i	1.467 (13)
C5—Se1—N2	86.5 (3)	C7—C6—H6A	108.5
N3—N2—Se1	110.6 (5)	C4—C6—H6B	108.5
N2—N3—C4	118.6 (6)	C7—C6—H6B	108.5
C5—C4—N3	113.7 (6)	H6A—C6—H6B	107.5
C5—C4—C6	127.2 (6)	C7i—C7—C6	116.2 (5)
N3—C4—C6	119.1 (6)	C7i—C7—H7A	108.2
C4—C5—C5i	124.0 (5)	C6—C7—H7A	108.2
C4—C5—Se1	110.7 (5)	C7i—C7—H7B	108.2
C5i—C5—Se1	125.3 (3)	C6—C7—H7B	108.2
C4—C6—C7	114.9 (5)	H7A—C7—H7B	107.4
C4—C6—H6A	108.5
C5—Se1—N2—N3	−0.1 (4)	C6—C4—C5—Se1	−177.1 (5)
Se1—N2—N3—C4	−0.1 (7)	N2—Se1—C5—C4	0.2 (4)
N2—N3—C4—C5	0.3 (8)	N2—Se1—C5—C5i	179.9 (6)
N2—N3—C4—C6	177.4 (5)	C5—C4—C6—C7	−87.5 (8)
N3—C4—C5—C5i	180.0 (6)	N3—C4—C6—C7	95.9 (7)
C6—C4—C5—C5i	3.2 (11)	C4—C6—C7—C7i	83.7 (8)
N3—C4—C5—Se1	−0.4 (7)

Symmetry code: (i) −x+1/2, y, −z+1.

3,14-Diselena-4,5,12,13-tetraazatricyclo[9.3.0.0^2,6]tetradeca-1(11),2(6),4,12-tetraene . Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7B···N2ii	0.99	2.61	3.466 (9)	144

Symmetry code: (ii) −x, y−1/2, −z+1/2.