4H,5H,6H,7H,8H,9H-Cyclo­octa­[d][1,2,3]selenadiazol-7-one

Detert, H.; Schollmeyer, D.

doi:10.1107/S2414314626011387

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 11| Part 11| November 2026| x261138

https://doi.org/10.1107/S2414314626011387

Open

access

4H,5H,6H,7H,8H,9H-Cycloocta[d][1,2,3]selenadiazol-7-one

Heiner Detert ^a ^* and Dieter Schollmeyer ^a

^aUniversity of Mainz, Department of Chemistry, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: [email protected]

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 28 October 2026; accepted 2 November 2026; online 6 November 2026)

In the title compound, C₈H₁₀N₂OSe, an almost planar 1,2,3-selenadiazole ring is annulated to a cyclooctenone ring with a twist-boat conformation. The heterocycle and C—C(=O)—C carbonyl moieties subtend a dihedral angle of 54.25 (11)°. In the extended structure, weak C—H⋯O and C—H⋯N interactions link the molecules into double layers lying parallel to the bc plane.

Keywords: crystal structure; selenium; Se-NMR; heterocycle; medium sized ring.

CCDC reference: 2599832

Structure description

The title compound, C₈H₁₀N₂OSe (I) (Fig. 1), was prepared in a project on medium sized rings with geometrical strain (Bissinger et al. 1988 ; Detert & Meier, 1997a ,b ). 1,2,3-Selenadiazoles are important precursors for the synthesis of strained cycloalkynes (Yalpani et al. 1971 ; Meier & Voigt,1972 ). The title compound had been prepared for the first synthesis of cyclooctynone (Meier & Petersen, 1978 ). The crystal structures of related cycloocteno-1,2,3-selanadiazoles have been reported recently (Schollmeyer & Detert, 2020 , 2025 ). The C4/C8/N7/N6/Se5 selenadiazole ring in (I) is planar to within 0.0044 (2) Å and the C2—C1(=O12)—C11 carbonyl moiety to within 0.004 (2) Å at C1; these planes subtend a dihedral angle of 54.25 (11)°. Further characteristics are a dihedral angle of 3.51 (19)° for the selenadiazole C4/C8 fragment and its adjacent methylene C atoms (C3—C4—C8—C9) and a twist-boat conformation of the cyclooctene ring.

Figure 1
The molecular structure of (I) with displacement ellipsoids drawn at the 50% probability level.

In the extended structure of (I), the molecules are connected via weak C—H⋯O and C—H⋯N hydrogen bonds with H⋯X (X = O, N) lengths of 2.58 to 2.68 Å (Table 1, Fig. 2). These bridges connect the molecules into a double-layer system with the layers lying parallel to the bc plane. Within one layer, the molecules are related by translation symmetry along the b axis and a c glide plane; a centre of inversion connects molecules of both layers, as centrosymmetric dimers are formed. While the C—H⋯O and C—H⋯N hydrogen bonds are within a layer and connect the double layer, the selenadiazole rings are on both surfaces of this subsystem.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2B⋯O12ⁱ	0.99	2.58	3.339 (3)	133
C3—H3A⋯N7ⁱⁱ	0.99	2.68	3.473 (3)	138
C9—H9A⋯O12ⁱⁱⁱ	0.99	2.65	3.608 (3)	162
C9—H9B⋯N7ⁱⁱ	0.99	2.64	3.547 (3)	152
C10—H10B⋯O12^iv	0.99	2.63	3.461 (3)	142
C11—H11A⋯O12ⁱ	0.99	2.63	3.467 (3)	143
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (iii) ; (iv) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 2
Partial packing diagram of (I) viewed along the b-axis direction. Hydrogen bonds are shown as dashed lines.

Synthesis and crystallization

The synthesis of the title compound was performed according to the literature (Meier & Petersen, 1978) from cyclooctadiene-1,5 via hydroboration/oxidation, partial oxidation of the diol, transformation of the ketone to a 1,2,3-selenadiazole and oxidation of the remaining alcohol group. After recrystallization from the mixed solvents of chloroform and propanol-2-ol, colourless blocks with m.p. 371 K were formed. Analytical data are given by Meier and Petersen (1978), ¹H-NMR (400 MHz, CDCl₂): δ = 3.45 (m, 2 H), 3.26 (m, 2 H), 2.73 (m, 2 H), 2.47 (m, 2 H), 1.98 (qui, 2 H). ⁷⁷Se-NMR (73 MHz, CDCl₃, SeO₂/D₂O as reference): δ = 223.7.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₈H₁₀N₂OSe
M_r	229.14
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	120
a, b, c (Å)	12.7015 (6), 7.2450 (2), 9.7070 (5)
β (°)	90.288 (4)
V (Å³)	893.25 (7)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	4.16
Crystal size (mm)	0.95 × 0.53 × 0.21

Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Integration
T_min, T_max	0.071, 0.405
No. of measured, independent and observed [I > 2σ(I)] reflections	4432, 2134, 2070
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.661

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.084, 1.14
No. of reflections	2134
No. of parameters	109
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.47, −0.89
Computer programs: X-AREA WinXpose, X-AREA Recipe and X-AREA Integrate (Stoe, 2020 ), SHELXT2014 (Sheldrick, 2015a ), SHELXL2019/2 (Sheldrick, 2015b ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 2599832

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314626011387/hb4580sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314626011387/hb4580Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314626011387/hb4580Isup3.cml

checkCIF report

Computing details top

4H,5H,6H,7H,8H,9H-Cycloocta[d][1,2,3]selenadiazol-7-one top

Crystal data top

C₈H₁₀N₂OSe	D_x = 1.704 Mg m⁻³
M_r = 229.14	Melting point: 371 K
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.7015 (6) Å	Cell parameters from 8908 reflections
b = 7.2450 (2) Å	θ = 2.6–28.6°
c = 9.7070 (5) Å	µ = 4.16 mm⁻¹
β = 90.288 (4)°	T = 120 K
V = 893.25 (7) Å³	Block, colorless
Z = 4	0.95 × 0.53 × 0.21 mm
F(000) = 456

Data collection top

Stoe IPDS 2T diffractometer	2070 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	R_int = 0.027
rotation method, ω scans	θ_max = 28.0°, θ_min = 3.2°
Absorption correction: integration	h = −16→16
T_min = 0.071, T_max = 0.405	k = −9→9
4432 measured reflections	l = −11→12
2134 independent reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.031	H-atom parameters constrained
wR(F²) = 0.084	w = 1/[σ²(F_o²) + (0.0513P)² + 0.6455P] where P = (F_o² + 2F_c²)/3
S = 1.14	(Δ/σ)_max = 0.001
2134 reflections	Δρ_max = 0.47 e Å⁻³
109 parameters	Δρ_min = −0.89 e Å⁻³
0 restraints

Special details top

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.

Refinement. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with C—H = 0.99 Å, and with U_iso(H) = 1.2 U_eq(C).

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

	x	y	z	U_iso*/U_eq
C1	0.17825 (15)	0.2685 (3)	0.3378 (2)	0.0186 (4)
C2	0.27398 (16)	0.2237 (3)	0.4249 (2)	0.0185 (4)
H2A	0.317187	0.129893	0.377209	0.022*
H2B	0.251056	0.170810	0.513922	0.022*
C3	0.34108 (16)	0.3969 (3)	0.4520 (2)	0.0179 (4)
H3A	0.303370	0.480159	0.515785	0.022*
H3B	0.408426	0.360662	0.496112	0.022*
C4	0.36298 (15)	0.4966 (3)	0.3194 (2)	0.0162 (4)
Se5	0.47241 (2)	0.43962 (3)	0.20325 (2)	0.01750 (10)
N6	0.41692 (15)	0.6158 (3)	0.08121 (18)	0.0211 (4)
N7	0.33379 (14)	0.6881 (2)	0.13071 (18)	0.0204 (3)
C8	0.30090 (16)	0.6286 (3)	0.2587 (2)	0.0177 (4)
C9	0.20190 (17)	0.7117 (3)	0.3166 (2)	0.0208 (4)
H9A	0.189133	0.831963	0.271053	0.025*
H9B	0.212906	0.735749	0.416032	0.025*
C10	0.10337 (17)	0.5907 (3)	0.2989 (2)	0.0222 (4)
H10A	0.097547	0.553333	0.201022	0.027*
H10B	0.040500	0.665579	0.321089	0.027*
C11	0.10277 (17)	0.4157 (3)	0.3892 (2)	0.0204 (4)
H11A	0.122305	0.449694	0.484777	0.024*
H11B	0.030593	0.364205	0.390915	0.024*
O12	0.16234 (13)	0.1908 (2)	0.22902 (17)	0.0251 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0176 (9)	0.0184 (9)	0.0198 (9)	−0.0023 (7)	0.0034 (7)	0.0011 (7)
C2	0.0202 (9)	0.0165 (9)	0.0188 (9)	0.0017 (7)	0.0022 (7)	0.0028 (7)
C3	0.0184 (9)	0.0207 (9)	0.0147 (8)	0.0011 (7)	−0.0005 (7)	0.0003 (7)
C4	0.0163 (9)	0.0163 (9)	0.0159 (8)	−0.0007 (7)	−0.0016 (7)	−0.0001 (7)
Se5	0.01565 (14)	0.01792 (15)	0.01893 (14)	−0.00037 (6)	0.00089 (9)	0.00129 (6)
N6	0.0239 (9)	0.0198 (8)	0.0195 (8)	−0.0040 (7)	−0.0010 (7)	0.0037 (7)
N7	0.0231 (8)	0.0181 (8)	0.0200 (8)	−0.0025 (6)	−0.0021 (7)	0.0037 (6)
C8	0.0203 (9)	0.0152 (9)	0.0176 (9)	−0.0014 (7)	−0.0028 (7)	0.0010 (7)
C9	0.0215 (10)	0.0173 (9)	0.0237 (9)	0.0059 (7)	−0.0026 (8)	−0.0003 (8)
C10	0.0170 (10)	0.0250 (9)	0.0245 (10)	0.0058 (8)	−0.0007 (8)	0.0002 (8)
C11	0.0152 (9)	0.0247 (10)	0.0212 (10)	0.0030 (7)	0.0019 (7)	−0.0004 (7)
O12	0.0256 (8)	0.0265 (8)	0.0232 (7)	−0.0025 (6)	0.0001 (6)	−0.0048 (6)

Geometric parameters (Å, º) top

C1—O12	1.213 (3)	N6—N7	1.275 (3)
C1—C2	1.513 (3)	N7—C8	1.381 (3)
C1—C11	1.520 (3)	C8—C9	1.506 (3)
C2—C3	1.539 (3)	C9—C10	1.537 (3)
C2—H2A	0.9900	C9—H9A	0.9900
C2—H2B	0.9900	C9—H9B	0.9900
C3—C4	1.503 (3)	C10—C11	1.542 (3)
C3—H3A	0.9900	C10—H10A	0.9900
C3—H3B	0.9900	C10—H10B	0.9900
C4—C8	1.371 (3)	C11—H11A	0.9900
C4—Se5	1.8410 (19)	C11—H11B	0.9900
Se5—N6	1.8766 (19)

O12—C1—C2	121.13 (19)	C4—C8—N7	115.38 (18)
O12—C1—C11	120.60 (19)	C4—C8—C9	126.73 (18)
C2—C1—C11	118.27 (17)	N7—C8—C9	117.89 (18)
C1—C2—C3	111.31 (16)	C8—C9—C10	114.28 (17)
C1—C2—H2A	109.4	C8—C9—H9A	108.7
C3—C2—H2A	109.4	C10—C9—H9A	108.7
C1—C2—H2B	109.4	C8—C9—H9B	108.7
C3—C2—H2B	109.4	C10—C9—H9B	108.7
H2A—C2—H2B	108.0	H9A—C9—H9B	107.6
C4—C3—C2	110.52 (17)	C9—C10—C11	114.31 (18)
C4—C3—H3A	109.5	C9—C10—H10A	108.7
C2—C3—H3A	109.5	C11—C10—H10A	108.7
C4—C3—H3B	109.5	C9—C10—H10B	108.7
C2—C3—H3B	109.5	C11—C10—H10B	108.7
H3A—C3—H3B	108.1	H10A—C10—H10B	107.6
C8—C4—C3	126.52 (18)	C1—C11—C10	112.67 (17)
C8—C4—Se5	109.12 (14)	C1—C11—H11A	109.1
C3—C4—Se5	124.05 (14)	C10—C11—H11A	109.1
C4—Se5—N6	87.23 (8)	C1—C11—H11B	109.1
N7—N6—Se5	110.53 (14)	C10—C11—H11B	109.1
N6—N7—C8	117.74 (18)	H11A—C11—H11B	107.8

O12—C1—C2—C3	122.5 (2)	C3—C4—C8—C9	4.8 (3)
C11—C1—C2—C3	−56.7 (2)	Se5—C4—C8—C9	178.63 (17)
C1—C2—C3—C4	−50.3 (2)	N6—N7—C8—C4	0.3 (3)
C2—C3—C4—C8	87.7 (2)	N6—N7—C8—C9	−179.16 (19)
C2—C3—C4—Se5	−85.2 (2)	C4—C8—C9—C10	−79.8 (3)
C8—C4—Se5—N6	0.78 (15)	N7—C8—C9—C10	99.6 (2)
C3—C4—Se5—N6	174.77 (17)	C8—C9—C10—C11	70.4 (2)
C4—Se5—N6—N7	−0.63 (15)	O12—C1—C11—C10	−67.1 (3)
Se5—N6—N7—C8	0.3 (2)	C2—C1—C11—C10	112.1 (2)
C3—C4—C8—N7	−174.62 (19)	C9—C10—C11—C1	−73.7 (2)
Se5—C4—C8—N7	−0.8 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···Se5ⁱ	0.99	3.11	4.025 (2)	154
C2—H2B···O12ⁱⁱ	0.99	2.58	3.339 (3)	133
C3—H3A···N7ⁱⁱⁱ	0.99	2.68	3.473 (3)	138
C3—H3B···Se5ⁱⁱ	0.99	3.07	3.825 (2)	134
C9—H9A···O12^iv	0.99	2.65	3.608 (3)	162
C9—H9B···N7ⁱⁱⁱ	0.99	2.64	3.547 (3)	152
C10—H10B···O12^v	0.99	2.63	3.461 (3)	142
C11—H11A···O12ⁱⁱ	0.99	2.63	3.467 (3)	143

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, −y+1/2, z+1/2; (iii) x, −y+3/2, z+1/2; (iv) x, y+1, z; (v) −x, y+1/2, −z+1/2.

References

Bissinger, H.-J., Detert, H. & Meier, H. (1988). Liebigs Ann. Chem. pp. 221–224. CrossRef Google Scholar
Detert, H. & Meier, H. (1997a). Liebigs Ann. Recl 1997, 1557–1563. CrossRef Google Scholar
Detert, H. & Meier, H. (1997b). Liebigs Ann. Recl 1997, 1565–1570. CrossRef Google Scholar
Meier, H. & Petersen, H. (1978). Synthesis pp. 596–598. Google Scholar
Meier, H. & Voigt, E. (1972). Tetrahedron 28, 187–198. CrossRef CAS Google Scholar
Schollmeyer, D. & Detert, H. (2020). IUCRData 5, x201585 Google Scholar
Schollmeyer, D. & Detert, H. (2025). IUCRData 10, x250324. Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stoe (2020). X-AREA WinXpose, X-AREA Recipe and X-AREA Integrate. Stoe & Cie, Darmstadt, Germany. Google Scholar
Yalpani, M., Lalezari, I. & Shafiee, A. (1971). J. Org. Chem. 36, 2836–2838. CrossRef CAS Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.