1-[1-(2,1,3-Benzoxa­diazol-5-ylmeth­yl)-1H-1,2,3-triazol-4-yl]hexan-1-one

The title compound, C₁₅H₁₇N₅O₂, was synthesized as part of a series of benzoxadiazole analogs which were examined for fluorescent properties by Cu-catalysed azide–alkyne cyclo­addition (CuAAC) of a 4-azido­methyl-benzoxadiazole substrate. The structure shows a nearly coplanar orientation of the hexa­none keto group and the 1,2,3-triazole ring [dihedral angle = 4.3 (3)°], while the benzoxadiazole and triazole groups are much more severely inclined [dihedral angle = 70.87 (4)°]. In the crystal, weak C—H⋯N inter­actions connect translationally-related triazole rings, while another set of C—H⋯N inter­actions is formed between inversion-related benzoxadiazole units, forming a three-dimensional network. The crystal studied was a non-merohedral twin with refined value of the twin fraction of 0.2289 (16).

Related literature

For the synthesis of similar benzoxadiazole compounds, see: Key & Cairo (2011); Li et al. (2010). For two related benzoxadiazole-triazole structures, see: Key, Cairo & Ferguson (2012); Key, Cairo & McDonald (2012). For structures of 1-(ar­yl)methyl-1,2,3-triazole compounds with 4-carbonyl substituents [RC(O) or ROC(O)], see: Harju et al. (2003); Huang et al. (2010); Dong & Cheng (2011); Jia & Lu (2011); Menendez et al. (2012).

Experimental

Crystal data

• C₁₅H₁₇N₅O₂

• M_r = 299.34

• Monoclinic, P 2₁ /c

• a = 16.5752 (16) Å

• b = 5.5429 (5) Å

• c = 16.2452 (16) Å

• β = 91.3612 (13)°

• V = 1492.1 (2) ų

• Z = 4

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 173 K

• 0.74 × 0.14 × 0.06 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (TWINABS; Bruker, 2008) T_min = 0.935, T_max = 0.995

• 45733 measured reflections

• 3079 independent reflections

• 2413 reflections with I > 2σ(I)

• R_int = 0.051

Refinement

• R[F² > 2σ(F²)] = 0.040

• wR(F²) = 0.091

• S = 1.03

• 3079 reflections

• 201 parameters

• H-atom parameters constrained

• Δρ_max = 0.19 e Å⁻³

• Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯N2^i	0.95	2.58	3.475 (2)	158
C8—H8⋯N5^ii	0.95	2.41	3.350 (2)	171
Symmetry codes: (i) -x, -y+1, -z; (ii) x, y-1, z.

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXD (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Supporting information

S1. Comment

In an effort to explore benzoxadiazole derivatives with interesting spectroscopic properties, we generated the title compound, I, for comparison to its parent 4-azidomethyl-benzoxadiazole (II). Although we observed large changes in the spectra of substrates with an azido group conjugated to the chromophore, derivatives with an intervening methylene group tended to have only small changes upon triazole formation (Key & Cairo, 2011). Compound I was synthesized unintentionally through the use of an oxidized sample of n-octyne which also contained oct-1-yn-3-one as an impurity. The hexanone product was isolated by column chromatography and used for structural studies. (λ_maxABS EtOH: 278, 289 nm, Absorption coefficient: 12,300 M^-1cm^-1)

In the crystal the 1,2,3-triazole ring and hexan-1-on-1-yl groups are nearly coplanar; the angle between the ketonic fragment (O2-C10-C11) and the 1,2,3-triazole ring is 4.3 (3)°. The rings of the benzoxadiazole and triazole groups are much more severely inclined (70.87 (4)°). Weak C-H···N interactions are observed between triazole moieties related via translation parallel to the b axis (2.41 Å for H8···N5[x, -1+y, z]). A further set of weak C-H···N interactions is seen between benzoxadiazole groups related by the inversion center (0, ¹/₂, 0) (2.58 Å for H3···N2[-x, 1-y, -z]). A parallel-stacking interaction is observed between benzoxadiazole rings related by inversion through the origin (interplanar spacing = 3.328 Å).

Related literature

For the synthesis of similar benzoxadiazole compounds, see: Key & Cairo (2011); Li et al. (2010). For two related benzoxadiazole-triazole structures, see: Key, Cairo & Ferguson (2012); Key, Cairo & McDonald (2012). For structures of 1-(aryl)methyl-1,2,3-triazole compounds with 4-carbonyl substituents [RC(O) or ROC(O)], see: Harju et al. (2003); Huang et al. (2010); Dong & Cheng (2011); Jia & Lu (2011); Menendez et al. (2012). Scheme: N═N double bond very short

S2. Experimental

4-(Azidomethyl)benz-[2,1,3-d]-oxadiazole (II) (40 mg, 0.23 mmol, 1 equiv) was dissolved in 1:1 water/methanol (5 mL). To this solution was added n-octyne (0.17 mL, 1.14 mmol, 5 equiv), which also contained oct-1-yn-3-one as an impurity. Copper sulfate (7 mg, 0.046 mmol, 0.2 equiv) and ascorbic acid (12 mg, 0.068 mmol, 0.3 equiv) were then added to the solution. The reaction mixture was allowed to stir at room temperature for approximately 1 h, forming a red precipitate. The precipitate was filtered off and the product was obtained after purification by column chromatography (EtOAc/hexanes) (35 mg, 51% yield). ¹H NMR (400 MHz, CDCl₃): δ 8.16 (s, 1H), 7.89 (d, 1H, ³J = 9.2 Hz), 7.51 (s, 1H), 7.32 (dd, 1H, ⁴J = 1.2 Hz, ³J = 9.2 Hz), 5.70 (s, 2H), 3.11(t, 2H, ³J = 7.2 Hz), 1.74 (m, 2H), 1.36 (m, 4H), 0.89 (m, 3H); ¹³C NMR (100 MHz, CDCl₃): δ 195.5, 149.1, 148.9, 148.8, 138.1, 131.1, 126.0, 118.5, 116.0, 54.1, 39.8, 31.6, 23.8, 22.7, 14.2; IR (microscope): ν = 3098, 2954, 2930, 1691, 1531 cm^-1; ES-HRMS calculated for C₁₅H₁₇N₅O₂Na [M+Na]⁺: 322.1279; observed: 322.1279. R_f = 0.45 (1:1 EtOAc/hexanes).

S3. Refinement

The crystal used for data collection was found to display non-merohedral twinning. Both components of the twin were indexed with the program CELL_NOW (Bruker, 2008). The second twin component can be related to the first component by 180° rotation about the [-1 0 2] axis in both real and reciprocal space. A raw data file was produced by the data integration program SAINT (Bruker, 2008), using the two-component orientation matrix file that had been produced by CELL_NOW. Integrated intensities for the reflections from the two components were written into a SHELXL-97 HKLF 5 reflection file with the program TWINABS (Bruker, 2008), using all reflection data (exactly overlapped, partially overlapped and non-overlapped). The reflection (1 0 0) was found to have an excessively high disagreement between F_o and F_c, and was omitted from the refinement. The refined value of the twin fraction (SHELXL-97 BASF parameter) was 0.2289 (16). All H atoms were generated in idealized positions and refined using a riding model with fixed C-H distances (C-H_aromatic = 0.95 Å, C-H_methylene = 0.99 Å, C-H_methyl = 0.98 Å) and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXD (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. View of I. Non-hydrogen atoms are represented by Gaussian ellipsoids at the 50% probability level. Hydrogen atoms are represented with artificially small thermal parameters.
	Fig. 2. Illustration of crystal packing as viewed parallel to the crystal b axis. Nonbonded C-H···N interactions are shown with dashed lines (see Table 1).
	Fig. 3. Compounds used in this study.

1-[1-(2,1,3-Benzoxadiazol-5-ylmethyl)-1H-1,2,3-triazol-4-yl]hexan-1-one

Crystal data

C15H17N5O2	F(000) = 632
Mr = 299.34	Dx = 1.333 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5974 reflections
a = 16.5752 (16) Å	θ = 2.5–24.3°
b = 5.5429 (5) Å	µ = 0.09 mm^−1
c = 16.2452 (16) Å	T = 173 K
β = 91.3612 (13)°	Rod, colourless
V = 1492.1 (2) Å^3	0.74 × 0.14 × 0.06 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	3079 independent reflections
Radiation source: fine-focus sealed tube	2413 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.051
Detector resolution: 8.26 pixels mm^-1	θmax = 26.5°, θmin = 1.2°
ω scans	h = −20→20
Absorption correction: multi-scan (TWINABS; Bruker, 2008)	k = −6→6
Tmin = 0.935, Tmax = 0.995	l = −20→20
45733 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)] = 0.040	H-atom parameters constrained
wR(F^2) = 0.091	w = 1/[σ^2(Fo^2) + (0.0331P)^2 + 0.4646P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
3079 reflections	Δρmax = 0.19 e Å^−3
201 parameters	Δρmin = −0.17 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0114 (15)

Special details

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
O1	−0.07380 (7)	0.1919 (2)	0.16041 (7)	0.0409 (3)
O2	0.51268 (8)	0.0088 (2)	0.11538 (10)	0.0593 (4)
N1	−0.03444 (8)	−0.0165 (3)	0.18558 (9)	0.0382 (4)
N2	−0.03404 (8)	0.3110 (3)	0.09850 (9)	0.0363 (3)
N3	0.29027 (7)	0.1559 (2)	0.00229 (8)	0.0272 (3)
N4	0.29675 (8)	0.3994 (2)	0.00904 (9)	0.0317 (3)
N5	0.36597 (7)	0.4428 (2)	0.04758 (9)	0.0309 (3)
C1	0.02958 (9)	−0.0270 (3)	0.13892 (9)	0.0287 (4)
C2	0.02964 (8)	0.1752 (3)	0.08476 (9)	0.0272 (3)
C3	0.09143 (9)	0.2061 (3)	0.02610 (9)	0.0278 (3)
H3	0.0918	0.3406	−0.0101	0.033*
C4	0.14968 (9)	0.0339 (3)	0.02451 (9)	0.0256 (3)
C5	0.14964 (9)	−0.1700 (3)	0.07982 (10)	0.0289 (3)
H5	0.1919	−0.2850	0.0766	0.035*
C6	0.09180 (9)	−0.2039 (3)	0.13617 (10)	0.0311 (4)
H6	0.0927	−0.3392	0.1721	0.037*
C7	0.21712 (9)	0.0526 (3)	−0.03636 (10)	0.0314 (4)
H7A	0.2294	−0.1098	−0.0580	0.038*
H7B	0.1994	0.1553	−0.0833	0.038*
C8	0.35461 (9)	0.0453 (3)	0.03618 (10)	0.0293 (4)
H8	0.3646	−0.1233	0.0395	0.035*
C9	0.40295 (9)	0.2287 (3)	0.06506 (10)	0.0288 (4)
C10	0.48268 (9)	0.2074 (3)	0.10742 (10)	0.0330 (4)
C11	0.52284 (9)	0.4320 (3)	0.13876 (11)	0.0331 (4)
H11A	0.4886	0.5057	0.1811	0.040*
H11B	0.5268	0.5484	0.0928	0.040*
C12	0.60693 (9)	0.3892 (3)	0.17585 (11)	0.0349 (4)
H12A	0.6029	0.2767	0.2229	0.042*
H12B	0.6409	0.3117	0.1341	0.042*
C13	0.64772 (9)	0.6203 (3)	0.20530 (10)	0.0320 (4)
H13A	0.6496	0.7355	0.1588	0.038*
H13B	0.6149	0.6941	0.2488	0.038*
C14	0.73289 (10)	0.5801 (3)	0.23904 (12)	0.0422 (4)
H14A	0.7665	0.5154	0.1946	0.051*
H14B	0.7315	0.4576	0.2833	0.051*
C15	0.77195 (11)	0.8090 (4)	0.27312 (11)	0.0450 (5)
H15A	0.8265	0.7723	0.2939	0.054*
H15B	0.7397	0.8722	0.3180	0.054*
H15C	0.7748	0.9300	0.2293	0.054*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0309 (6)	0.0481 (8)	0.0440 (7)	0.0059 (6)	0.0048 (5)	−0.0042 (6)
O2	0.0466 (8)	0.0264 (7)	0.1034 (13)	0.0055 (6)	−0.0278 (8)	−0.0033 (7)
N1	0.0341 (7)	0.0428 (9)	0.0379 (8)	0.0016 (7)	0.0028 (6)	−0.0012 (7)
N2	0.0316 (7)	0.0373 (8)	0.0400 (8)	0.0036 (6)	−0.0019 (6)	−0.0019 (7)
N3	0.0270 (6)	0.0249 (7)	0.0297 (7)	−0.0020 (5)	0.0035 (5)	−0.0010 (6)
N4	0.0301 (7)	0.0256 (7)	0.0395 (8)	−0.0010 (6)	0.0011 (6)	0.0004 (6)
N5	0.0277 (7)	0.0242 (7)	0.0409 (8)	−0.0001 (5)	0.0004 (6)	0.0006 (6)
C1	0.0264 (8)	0.0317 (9)	0.0279 (8)	−0.0042 (7)	−0.0016 (6)	−0.0018 (7)
C2	0.0244 (7)	0.0258 (8)	0.0310 (8)	−0.0003 (6)	−0.0061 (6)	−0.0037 (7)
C3	0.0304 (8)	0.0248 (8)	0.0281 (8)	−0.0035 (7)	−0.0041 (6)	0.0008 (7)
C4	0.0254 (7)	0.0259 (8)	0.0254 (8)	−0.0039 (6)	−0.0045 (6)	−0.0033 (6)
C5	0.0281 (8)	0.0250 (8)	0.0334 (8)	0.0024 (6)	−0.0024 (6)	−0.0016 (7)
C6	0.0354 (8)	0.0256 (8)	0.0323 (9)	−0.0004 (7)	−0.0019 (7)	0.0037 (7)
C7	0.0311 (8)	0.0339 (9)	0.0292 (9)	−0.0043 (7)	−0.0012 (6)	−0.0042 (7)
C8	0.0288 (8)	0.0235 (8)	0.0359 (9)	0.0006 (6)	0.0040 (6)	0.0007 (7)
C9	0.0277 (8)	0.0228 (8)	0.0359 (9)	0.0004 (6)	0.0036 (6)	−0.0001 (7)
C10	0.0290 (8)	0.0258 (9)	0.0442 (10)	0.0011 (7)	−0.0009 (7)	0.0014 (8)
C11	0.0287 (8)	0.0285 (9)	0.0422 (10)	−0.0003 (7)	−0.0007 (7)	−0.0011 (7)
C12	0.0323 (8)	0.0312 (9)	0.0410 (10)	−0.0020 (7)	−0.0037 (7)	0.0050 (8)
C13	0.0295 (8)	0.0344 (9)	0.0321 (9)	−0.0017 (7)	−0.0005 (7)	0.0001 (7)
C14	0.0370 (9)	0.0402 (11)	0.0488 (11)	−0.0043 (8)	−0.0115 (8)	0.0055 (9)
C15	0.0410 (10)	0.0518 (12)	0.0418 (11)	−0.0113 (9)	−0.0077 (8)	0.0025 (9)

Geometric parameters (Å, º)

O1—N2	1.3831 (18)	C7—H7B	0.9900
O1—N1	1.3835 (18)	C8—C9	1.370 (2)
O2—C10	1.214 (2)	C8—H8	0.9500
N1—C1	1.320 (2)	C9—C10	1.480 (2)
N2—C2	1.320 (2)	C10—C11	1.495 (2)
N3—C8	1.3376 (19)	C11—C12	1.524 (2)
N3—N4	1.3581 (18)	C11—H11A	0.9900
N3—C7	1.4682 (19)	C11—H11B	0.9900
N4—N5	1.3160 (17)	C12—C13	1.520 (2)
N5—C9	1.3627 (19)	C12—H12A	0.9900
C1—C2	1.425 (2)	C12—H12B	0.9900
C1—C6	1.425 (2)	C13—C14	1.519 (2)
C2—C3	1.426 (2)	C13—H13A	0.9900
C3—C4	1.358 (2)	C13—H13B	0.9900
C3—H3	0.9500	C14—C15	1.523 (2)
C4—C5	1.444 (2)	C14—H14A	0.9900
C4—C7	1.513 (2)	C14—H14B	0.9900
C5—C6	1.354 (2)	C15—H15A	0.9800
C5—H5	0.9500	C15—H15B	0.9800
C6—H6	0.9500	C15—H15C	0.9800
C7—H7A	0.9900
N2—O1—N1	112.57 (11)	N5—C9—C10	123.94 (14)
C1—N1—O1	104.30 (13)	C8—C9—C10	127.49 (14)
C2—N2—O1	104.33 (13)	O2—C10—C9	118.73 (15)
C8—N3—N4	111.20 (12)	O2—C10—C11	122.74 (14)
C8—N3—C7	129.75 (13)	C9—C10—C11	118.53 (14)
N4—N3—C7	119.02 (13)	C10—C11—C12	113.64 (14)
N5—N4—N3	106.65 (12)	C10—C11—H11A	108.8
N4—N5—C9	108.83 (12)	C12—C11—H11A	108.8
N1—C1—C2	109.40 (14)	C10—C11—H11B	108.8
N1—C1—C6	129.85 (15)	C12—C11—H11B	108.8
C2—C1—C6	120.73 (14)	H11A—C11—H11B	107.7
N2—C2—C1	109.39 (14)	C13—C12—C11	112.92 (14)
N2—C2—C3	129.38 (15)	C13—C12—H12A	109.0
C1—C2—C3	121.22 (14)	C11—C12—H12A	109.0
C4—C3—C2	116.78 (14)	C13—C12—H12B	109.0
C4—C3—H3	121.6	C11—C12—H12B	109.0
C2—C3—H3	121.6	H12A—C12—H12B	107.8
C3—C4—C5	121.82 (14)	C14—C13—C12	113.13 (14)
C3—C4—C7	120.05 (14)	C14—C13—H13A	109.0
C5—C4—C7	118.13 (14)	C12—C13—H13A	109.0
C6—C5—C4	122.70 (15)	C14—C13—H13B	109.0
C6—C5—H5	118.6	C12—C13—H13B	109.0
C4—C5—H5	118.6	H13A—C13—H13B	107.8
C5—C6—C1	116.74 (15)	C13—C14—C15	113.11 (15)
C5—C6—H6	121.6	C13—C14—H14A	109.0
C1—C6—H6	121.6	C15—C14—H14A	109.0
N3—C7—C4	111.25 (12)	C13—C14—H14B	109.0
N3—C7—H7A	109.4	C15—C14—H14B	109.0
C4—C7—H7A	109.4	H14A—C14—H14B	107.8
N3—C7—H7B	109.4	C14—C15—H15A	109.5
C4—C7—H7B	109.4	C14—C15—H15B	109.5
H7A—C7—H7B	108.0	H15A—C15—H15B	109.5
N3—C8—C9	104.76 (14)	C14—C15—H15C	109.5
N3—C8—H8	127.6	H15A—C15—H15C	109.5
C9—C8—H8	127.6	H15B—C15—H15C	109.5
N5—C9—C8	108.57 (13)
N2—O1—N1—C1	−0.28 (17)	C2—C1—C6—C5	−0.3 (2)
N1—O1—N2—C2	0.55 (16)	C8—N3—C7—C4	94.95 (19)
C8—N3—N4—N5	0.04 (18)	N4—N3—C7—C4	−82.78 (18)
C7—N3—N4—N5	178.17 (12)	C3—C4—C7—N3	98.31 (16)
N3—N4—N5—C9	0.00 (17)	C5—C4—C7—N3	−81.66 (17)
O1—N1—C1—C2	−0.09 (16)	N4—N3—C8—C9	−0.05 (17)
O1—N1—C1—C6	−178.92 (15)	C7—N3—C8—C9	−177.93 (14)
O1—N2—C2—C1	−0.58 (16)	N4—N5—C9—C8	−0.03 (18)
O1—N2—C2—C3	178.43 (14)	N4—N5—C9—C10	179.26 (15)
N1—C1—C2—N2	0.45 (18)	N3—C8—C9—N5	0.05 (17)
C6—C1—C2—N2	179.40 (14)	N3—C8—C9—C10	−179.21 (15)
N1—C1—C2—C3	−178.66 (14)	N5—C9—C10—O2	−175.34 (17)
C6—C1—C2—C3	0.3 (2)	C8—C9—C10—O2	3.8 (3)
N2—C2—C3—C4	−178.81 (15)	N5—C9—C10—C11	4.8 (2)
C1—C2—C3—C4	0.1 (2)	C8—C9—C10—C11	−176.09 (16)
C2—C3—C4—C5	−0.4 (2)	O2—C10—C11—C12	4.1 (3)
C2—C3—C4—C7	179.59 (13)	C9—C10—C11—C12	−176.03 (15)
C3—C4—C5—C6	0.4 (2)	C10—C11—C12—C13	178.46 (14)
C7—C4—C5—C6	−179.61 (14)	C11—C12—C13—C14	−177.59 (15)
C4—C5—C6—C1	0.0 (2)	C12—C13—C14—C15	−176.65 (15)
N1—C1—C6—C5	178.39 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···N2^i	0.95	2.58	3.475 (2)	158
C8—H8···N5^ii	0.95	2.41	3.350 (2)	171

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