Hydrogen-bonded networks in 1H-indazoles: the case of 7-methyl-1H-indazole

The secondary structure in the title compound, C₈H₈N₂, consists of infinite helical chains formed by molecules linked by N—H...N hydrogen bonds. Neighbouring chains are connected by C—H...π(azole) contacts.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.039
• wR factor = 0.115
• Data-to-parameter ratio = 8.3

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT035_ALERT_1_A No _chemical_absolute_configuration info given .          ?

Author Response: Compound (I) is achiral but crystallizes in a chiral space group. Although it does not contain heavier atoms than N, all the Friedel pairs were collected using Cu radiation. Refinement of the Flack parameter (Flack, 1983) led to a meaningless value of 0.1(10) and, therefore, Friedel pairs were merged prior to the final refinement.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           66.96
           From the CIF: _reflns_number_total                759
           Count of symmetry unique reflns          761
           Completeness (_total/calc)             99.74%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

   1 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: XRD3000-S software (Seifert, 1996); cell refinement: LSUCRE (Appleman, 1984); data reduction: Xtal3.6 (Hall et al., 1999); program(s) used to solve structure: Sir97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Xtal3.6; software used to prepare material for publication: SHELXL97 and WinGX (Farrugia, 1999).

7-Methyl-1H-indazole

Crystal data

C8H8N2	Dx = 1.254 Mg m^−3
Mr = 132.16	Melting point: 411 K
Orthorhombic, P212121	Cu Kα radiation, λ = 1.54180 Å
Hall symbol: P 2ac 2ab	Cell parameters from 47 reflections
a = 12.0013 (11) Å	θ = 2–45°
b = 11.1465 (11) Å	µ = 0.61 mm^−1
c = 5.2327 (4) Å	T = 295 K
V = 699.99 (11) Å^3	Prism, colourless
Z = 4	0.50 × 0.20 × 0.13 mm
F(000) = 280

Data collection

Manufacturer? Model? four-circle diffractometer	Rint = 0.047
Radiation source: fine-focus sealed tube	θmax = 67.0°, θmin = 5.4°
Graphite monochromator	h = −14→14
ω/2θ scans	k = −13→13
1504 measured reflections	l = −6→6
759 independent reflections	2 standard reflections every 100 min
692 reflections with I > 2σ(I)	intensity decay: 5.5%

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.039	w = 1/[σ^2(Fo^2) + (0.0704P)^2 + 0.0866P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.115	(Δ/σ)max < 0.001
S = 1.04	Δρmax = 0.15 e Å^−3
759 reflections	Δρmin = −0.12 e Å^−3
92 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.070 (7)
Primary atom site location: structure-invariant direct methods	Absolute structure: see experimental
Secondary atom site location: difference Fourier map

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. 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
N1	0.34780 (16)	0.4508 (2)	0.0148 (4)	0.0459 (6)
H1	0.2862	0.4350	−0.0620	0.055*
N2	0.35709 (18)	0.52842 (19)	0.2133 (5)	0.0503 (6)
C3	0.4632 (2)	0.5275 (2)	0.2801 (6)	0.0497 (7)
H3	0.4929	0.5720	0.4142	0.060*
C3A	0.5261 (2)	0.4497 (2)	0.1203 (5)	0.0439 (6)
C4	0.6392 (2)	0.4142 (3)	0.1034 (6)	0.0549 (8)
H4	0.6928	0.4445	0.2143	0.066*
C5	0.6660 (2)	0.3335 (3)	−0.0827 (7)	0.0597 (8)
H5	0.7398	0.3096	−0.1000	0.072*
C6	0.5856 (2)	0.2853 (2)	−0.2496 (6)	0.0559 (8)
H6	0.6084	0.2305	−0.3729	0.067*
C7	0.4747 (2)	0.3162 (2)	−0.2375 (5)	0.0449 (6)
C7A	0.4479 (2)	0.4007 (2)	−0.0487 (5)	0.0405 (6)
C8	0.3878 (2)	0.2636 (3)	−0.4089 (6)	0.0589 (8)
H8A	0.3386	0.3259	−0.4665	0.071*
H8B	0.3459	0.2044	−0.3167	0.071*
H8C	0.4230	0.2267	−0.5536	0.071*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0351 (10)	0.0531 (11)	0.0495 (13)	0.0048 (9)	−0.0007 (10)	−0.0025 (10)
N2	0.0466 (12)	0.0534 (12)	0.0510 (13)	0.0060 (10)	0.0065 (12)	−0.0055 (11)
C3	0.0460 (14)	0.0554 (14)	0.0476 (14)	−0.0011 (11)	−0.0012 (13)	−0.0056 (13)
C3A	0.0394 (12)	0.0477 (12)	0.0447 (13)	0.0007 (10)	0.0004 (12)	0.0061 (12)
C4	0.0362 (12)	0.0683 (17)	0.0604 (17)	0.0025 (12)	−0.0021 (14)	0.0028 (15)
C5	0.0403 (13)	0.0714 (18)	0.067 (2)	0.0146 (13)	0.0066 (14)	0.0048 (17)
C6	0.0570 (16)	0.0562 (14)	0.0545 (18)	0.0118 (13)	0.0086 (15)	0.0002 (15)
C7	0.0521 (14)	0.0433 (12)	0.0393 (13)	0.0033 (11)	0.0057 (13)	0.0079 (11)
C7A	0.0392 (11)	0.0446 (11)	0.0376 (12)	0.0046 (9)	0.0031 (11)	0.0103 (11)
C8	0.0629 (16)	0.0583 (15)	0.0554 (17)	−0.0015 (13)	0.0029 (15)	−0.0034 (15)

Geometric parameters (Å, º)

N1—N2	1.356 (3)	C5—C6	1.408 (4)
N1—C7A	1.366 (3)	C5—H5	0.9300
N1—H1	0.8600	C6—C7	1.376 (4)
N2—C3	1.320 (4)	C6—H6	0.9300
C3—C3A	1.422 (4)	C7—C7A	1.402 (3)
C3—H3	0.9300	C7—C8	1.496 (4)
C3A—C7A	1.400 (4)	C8—H8A	0.9600
C3A—C4	1.417 (3)	C8—H8B	0.9600
C4—C5	1.364 (4)	C8—H8C	0.9600
C4—H4	0.9300
N2—N1—C7A	112.00 (19)	C7—C6—C5	122.6 (3)
N2—N1—H1	124.0	C7—C6—H6	118.7
C7A—N1—H1	124.0	C5—C6—H6	118.7
C3—N2—N1	106.1 (2)	C6—C7—C7A	115.0 (3)
N2—C3—C3A	111.1 (2)	C6—C7—C8	123.3 (3)
N2—C3—H3	124.4	C7A—C7—C8	121.8 (2)
C3A—C3—H3	124.4	N1—C7A—C3A	106.0 (2)
C7A—C3A—C4	119.5 (3)	N1—C7A—C7	130.3 (2)
C7A—C3A—C3	104.7 (2)	C3A—C7A—C7	123.6 (2)
C4—C3A—C3	135.7 (3)	C7—C8—H8A	109.5
C5—C4—C3A	117.0 (3)	C7—C8—H8B	109.5
C5—C4—H4	121.5	H8A—C8—H8B	109.5
C3A—C4—H4	121.5	C7—C8—H8C	109.5
C4—C5—C6	122.2 (2)	H8A—C8—H8C	109.5
C4—C5—H5	118.9	H8B—C8—H8C	109.5
C6—C5—H5	118.9
C7A—N1—N2—C3	−0.7 (3)	N2—N1—C7A—C3A	−0.1 (3)
N1—N2—C3—C3A	1.1 (3)	N2—N1—C7A—C7	179.2 (2)
N2—C3—C3A—C7A	−1.2 (3)	C4—C3A—C7A—N1	179.6 (2)
N2—C3—C3A—C4	−179.8 (3)	C3—C3A—C7A—N1	0.7 (3)
C7A—C3A—C4—C5	0.8 (4)	C4—C3A—C7A—C7	0.3 (4)
C3—C3A—C4—C5	179.2 (3)	C3—C3A—C7A—C7	−178.6 (2)
C3A—C4—C5—C6	−1.0 (4)	C6—C7—C7A—N1	179.8 (3)
C4—C5—C6—C7	0.2 (4)	C8—C7—C7A—N1	−0.9 (4)
C5—C6—C7—C7A	0.9 (4)	C6—C7—C7A—C3A	−1.1 (3)
C5—C6—C7—C8	−178.4 (2)	C8—C7—C7A—C3A	178.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···N2^i	0.86	2.12	2.931 (3)	156

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