Experimental charge density and electrostatic potential in nicotinamide

Miwa, Y.; Mizuno, T.; Tsuchida, K.; Taga, T.; Iwata, Y.

doi:10.1107/S0108768198007848

Experimental charge density and electrostatic potential in nicotinamide

Y. Miwa, T. Mizuno, K. Tsuchida, T. Taga and Y. Iwata

The accurate crystal structure of nicotinamide, 3-pyridinecarboxamide, was determined from X-ray and neutron diffraction experiments: C₆H₆N₂O, M_r = 122.13, monoclinic, P2₁/c, Z = 4. The electron distribution at 150 K was determined by the maximum entropy method and the electrostatic potential in the crystal was calculated by Fourier convolution of the electron distribution. The electrostatic properties of the nicotinamide molecule depend on the molecular conformation. The asymmetric electrostatic potential field observed above and below the pyridine-ring plane is related to the rotation of the carboxamide group with respect to the pyridine plane. The positive potential peak at the C4 atom of the pyridine ring extends to the C=O-group side of the plane. The asymmetry of the potential on the C4 atom is consistent with the stereospecificity of hydride transfer in NAD⁺/NADH oxidoreduction.

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Supporting information

	Crystallographic Information File (CIF) Contains datablocks text, NAD150X, NAD295X, NAD295N
	Structure factor file (CIF format) Contains datablock NAD295X
	Structure factor file (CIF format) Contains datablock NAD295N
	Structure factor file (CIF format) Contains datablock NAD150X

CCDC references: 131756; 131757; 131758

Computing details top

Data collection: Rigaku/AFC5 for NAD150X, NAD295X; 4CND for NAD295N. Cell refinement: MSC/AFC (MSC, 1988) for NAD150X, NAD295X. Data reduction: MSC/AFC (MSC, 1988) for NAD150X, NAD295X; 4CND software for NAD295N. For all compounds, program(s) used to solve structure: MULTAN88(Main et al., 1988). Program(s) used to refine structure: Full-MATRIX LEAST-SQUARE for NAD150X; Full-matrix least-squares for NAD295X, NAD295N. For all compounds, molecular graphics: KPPXRAY; software used to prepare material for publication: EDCIF-J.

Figures top

(NAD150X) top

Crystal data top

C₆H₆N₂O	F(000) = 256
M_r = 122.13	D_x = 1.446 Mg m⁻³ D_m = 1.398 (at room temp.) Mg m⁻³ D_m measured by ?
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 3.877 (4) Å	Cell parameters from 25 reflections
b = 15.60 (1) Å	θ = 8.4–13.5°
c = 9.375 (6) Å	µ = 0.10 mm⁻¹
β = 98.45 (7)°	T = 150 K
V = 560.8 Å³	, colorless
Z = 4	0.70 × 0.70 × 0.60 mm

Data collection top

Rigaku AFC5-RU200 diffractometer	R_int = 0.024
Radiation source: rotarix	θ_max = 55°, θ_min = 1°
Graphite monochromator	h = 0→8
ω/2θ scans	k = 0→35
6781 measured reflections	l = −21→21
6199 independent reflections	3 standard reflections every 150 reflections
4810 reflections with F > 3σ(F)	intensity decay: 8%

Refinement top

Refinement on F	Refxyz all from D-map
Least-squares matrix: Full-matrix least-squares	w = 1/[σ²(F) + 0.08F²]
R[F² > 2σ(F²)] = 0.054	(Δ/σ)_max = 0.01
wR(F²) = 0.056	Δρ_max = 0.47 e Å⁻³
4810 reflections	Δρ_min = −0.26 e Å⁻³
106 parameters

Crystal data top

C₆H₆N₂O	V = 560.8 Å³
M_r = 122.13	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 3.877 (4) Å	µ = 0.10 mm⁻¹
b = 15.60 (1) Å	T = 150 K
c = 9.375 (6) Å	0.70 × 0.70 × 0.60 mm
β = 98.45 (7)°

Data collection top

Rigaku AFC5-RU200 diffractometer	R_int = 0.024
6781 measured reflections	3 standard reflections every 150 reflections
6199 independent reflections	intensity decay: 8%
4810 reflections with F > 3σ(F)

Refinement top

R[F² > 2σ(F²)] = 0.054	Refxyz all from D-map
wR(F²) = 0.056	Δρ_max = 0.47 e Å⁻³
4810 reflections	Δρ_min = −0.26 e Å⁻³
106 parameters

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

	x	y	z	U_iso*/U_eq
C2	−0.0384 (2)	0.33937 (4)	0.19344 (6)	0.01989 (8)
C3	0.1528 (1)	0.35815 (4)	0.32749 (5)	0.01734 (8)
C4	0.1745 (2)	0.44285 (4)	0.37152 (6)	0.0231 (1)
C5	0.0184 (2)	0.50592 (4)	0.28065 (7)	0.0265 (2)
C6	−0.1644 (2)	0.48110 (4)	0.14914 (7)	0.0235 (2)
C7	0.3283 (2)	0.29179 (4)	0.42823 (5)	0.01934 (8)
N1	−0.1976 (1)	0.39949 (3)	0.10545 (5)	0.02188 (8)
N2	0.4058 (2)	0.21699 (4)	0.37214 (6)	0.0240 (1)
O1	0.3963 (1)	0.30857 (3)	0.55835 (4)	0.0272 (1)
HC2	−0.083 (3)	0.2843 (6)	0.158 (1)	0.029 (3)*
HC4	0.312 (3)	0.4549 (7)	0.473 (1)	0.039 (3)*
HC5	0.023 (3)	0.5620 (8)	0.314 (1)	0.043 (3)*
HC6	−0.275 (3)	0.5229 (7)	0.079 (1)	0.034 (3)*
HN2A	0.400 (3)	0.2102 (7)	0.278 (1)	0.047 (3)*
HN2B	0.511 (3)	0.1770 (7)	0.434 (1)	0.052 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C2	0.0237 (2)	0.0196 (2)	0.0143 (2)	−0.0006 (2)	−0.0033 (2)	−0.0006 (1)
C3	0.0198 (2)	0.0190 (2)	0.0127 (2)	−0.0025 (2)	−0.0015 (1)	0.0001 (1)
C4	0.0279 (3)	0.0207 (2)	0.0183 (2)	−0.0032 (2)	−0.0036 (2)	−0.0023 (1)
C5	0.0342 (3)	0.0184 (2)	0.0247 (3)	−0.0008 (2)	−0.0021 (2)	−0.0012 (2)
C6	0.0277 (3)	0.0211 (2)	0.0204 (2)	0.0020 (2)	−0.0008 (2)	0.0026 (1)
C7	0.0229 (2)	0.0205 (2)	0.0128 (2)	−0.0028 (2)	−0.0023 (1)	0.0015 (1)
N1	0.0258 (2)	0.0219 (2)	0.0156 (2)	0.0015 (2)	−0.0036 (1)	0.0010 (1)
N2	0.0331 (3)	0.0207 (2)	0.0156 (2)	0.0019 (2)	−0.0039 (2)	0.0013 (1)
O1	0.0385 (3)	0.0281 (2)	0.0123 (1)	0.0005 (2)	−0.0046 (1)	0.0004 (1)

Geometric parameters (Å, º) top

C2—C3	1.393 (1)	C7—O1	1.238 (1)
C2—N1	1.338 (1)	C2—HC2	0.928 (9)
C3—C4	1.383 (1)	C4—HC4	1.037 (9)
C3—C7	1.496 (1)	C5—HC5	0.93 (1)
C4—C5	1.381 (1)	C6—HC6	0.98 (1)
C5—C6	1.384 (1)	N2—HN2A	0.88 (1)
C6—N1	1.338 (1)	N2—HN2B	0.91 (1)
C7—N2	1.332 (1)

C3—C2—N1	123.01 (7)	C3—C2—HC2	124.3 (6)
C2—C3—C4	118.10 (5)	N1—C2—HC2	112.5 (6)
C2—C3—C7	123.81 (7)	C3—C4—HC4	116.6 (6)
C4—C3—C7	118.07 (7)	C5—C4—HC4	123.8 (6)
C3—C4—C5	119.62 (7)	C4—C5—HC5	118.6 (6)
C4—C5—C6	118.08 (8)	C6—C5—HC5	123.1 (6)
C5—C6—N1	123.55 (6)	C5—C6—HC6	121.9 (6)
C3—C7—N2	117.70 (6)	N1—C6—HC6	114.5 (6)
C3—C7—O1	119.16 (7)	C7—N2—HN2A	121.6 (7)
N2—C7—O1	123.13 (6)	C7—N2—HN2B	117.2 (6)
C2—N1—C6	117.59 (7)

C2—C3—C4—C5	−2.1 (1)	C4—C3—C7—O1	20.81 (9)
C2—C3—C7—N2	22.8 (1)	C4—C5—C6—N1	−0.0 (1)
C2—C3—C7—O1	−157.54 (6)	C5—C6—N1—C2	−1.4 (1)
C3—C2—N1—C6	1.0 (1)	C7—C3—C4—C5	179.37 (7)
C3—C4—C5—C6	1.9 (1)	N1—C2—C3—C4	0.7 (1)
C4—C3—C7—N2	−158.81 (7)	N1—C2—C3—C7	179.10 (6)

(NAD295X) top

Crystal data top

C₆H₆N₂O	F(000) = 256
M_r = 122.13	D_x = 1.403 Mg m⁻³ D_m = 1.398 Mg m⁻³ D_m measured by flotation
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 3.975 (5) Å	Cell parameters from 25 reflections
b = 15.632 (8) Å	θ = 8.1–13.5°
c = 9.422 (4) Å	µ = 0.10 mm⁻¹
β = 99.03 (7)°	T = 295 K
V = 578.2 Å³	, colorless
Z = 4	0.80 × 0.70 × 0.60 mm

Data collection top

Rigaku AFC5-RU200 diffractometer	R_int = 0.009
Radiation source: rotarix	θ_max = 52.5°, θ_min = 1°
Graphite monochromator	h = 0→8
ω/2θ scans	k = 0→33
5771 measured reflections	l = −21→20
5246 independent reflections	3 standard reflections every 150 reflections
3471 reflections with F > 3σ(F)	intensity decay: 5%

Refinement top

Refinement on F	Refxyz all from D-map
Least-squares matrix: Full-matrix least-squares	w = 1/[σ²(F) + 0.08F²]
R[F² > 2σ(F²)] = 0.057	(Δ/σ)_max = 0.01
wR(F²) = 0.066	Δρ_max = 0.49 e Å⁻³
3471 reflections	Δρ_min = −0.18 e Å⁻³
106 parameters

Crystal data top

C₆H₆N₂O	V = 578.2 Å³
M_r = 122.13	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 3.975 (5) Å	µ = 0.10 mm⁻¹
b = 15.632 (8) Å	T = 295 K
c = 9.422 (4) Å	0.80 × 0.70 × 0.60 mm
β = 99.03 (7)°

Data collection top

Rigaku AFC5-RU200 diffractometer	R_int = 0.009
5771 measured reflections	3 standard reflections every 150 reflections
5246 independent reflections	intensity decay: 5%
3471 reflections with F > 3σ(F)

Refinement top

R[F² > 2σ(F²)] = 0.057	Refxyz all from D-map
wR(F²) = 0.066	Δρ_max = 0.49 e Å⁻³
3471 reflections	Δρ_min = −0.18 e Å⁻³
106 parameters

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

	x	y	z	U_iso*/U_eq
C2	−0.0311 (2)	0.33966 (5)	0.19385 (7)	0.0373 (2)
C3	0.1575 (2)	0.35848 (5)	0.32724 (6)	0.0332 (1)
C4	0.1764 (2)	0.44290 (5)	0.37032 (8)	0.0453 (2)
C5	0.0192 (3)	0.50513 (6)	0.2801 (1)	0.0521 (2)
C6	−0.1597 (2)	0.48025 (6)	0.14974 (9)	0.0465 (2)
C7	0.3328 (2)	0.29227 (5)	0.42755 (6)	0.0369 (2)
N1	−0.1914 (2)	0.39915 (5)	0.10621 (6)	0.0427 (2)
N2	0.4104 (2)	0.21807 (5)	0.37194 (7)	0.0461 (2)
O1	0.4007 (2)	0.30880 (4)	0.55698 (5)	0.0528 (2)
HC2	−0.067 (3)	0.2827 (8)	0.168 (1)	0.054 (3)*
HC4	0.311 (3)	0.4568 (8)	0.469 (1)	0.072 (4)*
HC5	0.033 (3)	0.5624 (9)	0.305 (1)	0.068 (4)*
HC6	−0.267 (3)	0.5207 (9)	0.074 (1)	0.071 (4)*
HN2A	0.400 (3)	0.2127 (7)	0.277 (1)	0.060 (3)*
HN2B	0.521 (3)	0.1763 (7)	0.425 (1)	0.061 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C2	0.0458 (4)	0.0390 (4)	0.0251 (2)	−0.0012 (3)	−0.0032 (2)	−0.0018 (2)
C3	0.0364 (3)	0.0381 (2)	0.0232 (2)	−0.0058 (2)	0.0003 (2)	0.0001 (2)
C4	0.0545 (4)	0.0416 (4)	0.0356 (3)	−0.0074 (3)	−0.0048 (3)	−0.0059 (3)
C5	0.0683 (6)	0.0370 (4)	0.0478 (4)	−0.0018 (4)	−0.0007 (4)	−0.0030 (3)
C6	0.0547 (5)	0.0432 (4)	0.0399 (4)	0.0044 (3)	0.0020 (3)	0.0064 (3)
C7	0.0436 (4)	0.0418 (4)	0.0228 (2)	−0.0065 (3)	−0.0021 (2)	0.0023 (2)
N1	0.0509 (4)	0.0459 (4)	0.0282 (2)	0.0034 (3)	−0.0042 (2)	0.0018 (2)
N2	0.0642 (5)	0.0418 (4)	0.0280 (3)	0.0038 (3)	−0.0046 (3)	0.0030 (2)
O1	0.0754 (4)	0.0574 (4)	0.0220 (2)	0.0004 (3)	−0.0058 (2)	0.0003 (2)

Geometric parameters (Å, º) top

C2—C3	1.390 (1)	C7—O1	1.2343 (9)
C2—N1	1.337 (1)	C2—HC2	0.93 (1)
C3—C4	1.379 (1)	C4—HC4	1.02 (1)
C3—C7	1.498 (1)	C5—HC5	0.93 (1)
C4—C5	1.376 (1)	C6—HC6	1.00 (1)
C5—C6	1.375 (2)	N2—HN2A	0.89 (1)
C6—N1	1.332 (1)	N2—HN2B	0.89 (1)
C7—N2	1.329 (1)

C3—C2—N1	123.25 (8)	C3—C2—HC2	119.1 (6)
C2—C3—C4	117.73 (7)	N1—C2—HC2	117.3 (6)
C2—C3—C7	123.76 (8)	C3—C4—HC4	117.9 (7)
C4—C3—C7	118.49 (7)	C5—C4—HC4	122.4 (7)
C3—C4—C5	119.75 (8)	C4—C5—HC5	121.2 (6)
C4—C5—C6	118.22 (9)	C6—C5—HC5	120.6 (6)
C5—C6—N1	123.69 (8)	C5—C6—HC6	123.9 (7)
C3—C7—N2	117.92 (6)	N1—C6—HC6	112.3 (6)
C3—C7—O1	119.13 (8)	C7—N2—HN2A	120.1 (7)
N2—C7—O1	122.96 (7)	C7—N2—HN2B	122.5 (6)
C2—N1—C6	117.31 (7)

C2—C3—C4—C5	−1.8 (1)	C4—C3—C7—O1	21.0 (1)
C2—C3—C7—N2	23.1 (1)	C4—C5—C6—N1	0.5 (2)
C2—C3—C7—O1	−157.38 (8)	C5—C6—N1—C2	−1.9 (1)
C3—C2—N1—C6	1.4 (1)	C7—C3—C4—C5	179.69 (9)
C3—C4—C5—C6	1.4 (1)	N1—C2—C3—C4	0.4 (1)
C4—C3—C7—N2	−158.50 (8)	N1—C2—C3—C7	178.82 (8)

(NAD295N) top

Crystal data top

C₆H₆N₂O	Z = 4
M_r = 122.13	D_x = 1.403 Mg m⁻³ D_m = 1.398 Mg m⁻³ D_m measured by floatation
Monoclinic, P2₁/c	Neutron radiation, λ = 1.005 (3) Å
a = 3.975 (5) Å	µ = 0.83 mm⁻¹
b = 15.632 (8) Å	T = 295 K
c = 9.422 (4) Å	, colorless
β = 99.03 (7)°	6.0 × 4.0 × 4.0 mm
V = 578.2 Å³

Data collection top

Four-circle diffractometer	R_int = 0.022
Radiation source: KUR	θ_max = 45°, θ_min = 1°
Cu(220) monochromator	h = 0→5
ω/2θ scans	k = 0→17
1748 measured reflections	l = −10→10
1739 independent reflections	1 standard reflections every 200 reflections
1026 reflections with F > 3σ(F)	intensity decay: 1.5%

Refinement top

Refinement on F	137 parameters
Least-squares matrix: Full-matrix least-squares	All H-atom parameters refined
R[F² > 2σ(F²)] = 0.060	w = 1/[σ²(F) + 0.04F²]
wR(F²) = 0.068	(Δ/σ)_max = 0.01
1026 reflections	Extinction correction: Zachariasen (1967) approximation

Crystal data top

C₆H₆N₂O	V = 578.2 Å³
M_r = 122.13	Z = 4
Monoclinic, P2₁/c	Neutron radiation, λ = 1.005 (3) Å
a = 3.975 (5) Å	µ = 0.83 mm⁻¹
b = 15.632 (8) Å	T = 295 K
c = 9.422 (4) Å	6.0 × 4.0 × 4.0 mm
β = 99.03 (7)°

Data collection top

Four-circle diffractometer	R_int = 0.022
1748 measured reflections	1 standard reflections every 200 reflections
1739 independent reflections	intensity decay: 1.5%
1026 reflections with F > 3σ(F)

Refinement top

R[F² > 2σ(F²)] = 0.060	137 parameters
wR(F²) = 0.068	All H-atom parameters refined
1026 reflections

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

	x	y	z	U_iso*/U_eq
C2	−0.0309 (2)	0.33933 (5)	0.19415 (8)	0.0392 (2)
C3	0.1567 (2)	0.35806 (5)	0.32705 (7)	0.0335 (2)
C4	0.1769 (3)	0.44289 (5)	0.37108 (9)	0.0467 (3)
C5	0.0186 (3)	0.50563 (6)	0.2804 (1)	0.0535 (3)
C6	−0.1626 (3)	0.48076 (5)	0.14954 (9)	0.0476 (3)
C7	0.3326 (2)	0.29247 (5)	0.42746 (7)	0.0385 (2)
N1	−0.1911 (2)	0.39919 (4)	0.10646 (6)	0.0444 (2)
N2	0.4113 (2)	0.21779 (4)	0.37183 (6)	0.0474 (2)
O1	0.4022 (3)	0.30864 (7)	0.55649 (9)	0.0521 (3)
HC2	−0.0645 (6)	0.2747 (1)	0.1560 (2)	0.0653 (7)
HC4	0.3135 (8)	0.4578 (1)	0.4781 (2)	0.0833 (9)
HC5	0.0309 (9)	0.5724 (2)	0.3109 (3)	0.094 (1)
HC6	−0.2889 (8)	0.5278 (1)	0.0762 (3)	0.0798 (9)
HN2A	0.3942 (6)	0.2097 (1)	0.2656 (2)	0.0614 (6)
HN2B	0.5358 (6)	0.1733 (1)	0.4388 (2)	0.0624 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C2	0.0499 (4)	0.0371 (4)	0.0288 (4)	−0.0019 (3)	0.0002 (3)	−0.0018 (3)
C3	0.0400 (4)	0.0340 (4)	0.0257 (3)	−0.0045 (3)	0.0024 (3)	−0.0005 (2)
C4	0.0574 (5)	0.0409 (5)	0.0381 (4)	−0.0078 (4)	−0.0041 (4)	−0.0058 (3)
C5	0.0707 (6)	0.0359 (5)	0.0521 (5)	0.0021 (4)	0.0035 (4)	−0.0014 (3)
C6	0.0632 (6)	0.0369 (5)	0.0421 (4)	0.0049 (4)	0.0059 (4)	0.0025 (3)
C7	0.0488 (4)	0.0414 (4)	0.0236 (4)	−0.0034 (3)	0.0006 (3)	0.0011 (2)
N1	0.0539 (4)	0.0441 (4)	0.0321 (3)	0.0033 (2)	−0.0025 (2)	0.0015 (2)
N2	0.0663 (4)	0.0403 (2)	0.0330 (3)	0.0035 (3)	−0.0001 (2)	0.0021 (2)
O1	0.0737 (7)	0.0546 (6)	0.0256 (4)	0.0007 (5)	0.0007 (4)	0.0000 (4)
HC2	0.092 (1)	0.049 (1)	0.0477 (8)	0.0002 (9)	−0.0088 (9)	−0.0088 (7)
HC4	0.118 (2)	0.064 (1)	0.059 (1)	−0.014 (1)	−0.016 (1)	−0.0144 (9)
HC5	0.137 (2)	0.050 (1)	0.086 (2)	0.002 (1)	−0.011 (2)	−0.006 (1)
HC6	0.117 (2)	0.047 (1)	0.070 (1)	0.015 (1)	−0.001 (1)	0.0109 (8)
HN2A	0.086 (1)	0.055 (1)	0.0417 (9)	0.006 (1)	0.0080 (8)	−0.0032 (7)
HN2B	0.080 (1)	0.054 (1)	0.0491 (9)	0.0007 (9)	−0.0037 (8)	0.0079 (7)

Geometric parameters (Å, º) top

C2—C3	1.384 (1)	C7—O1	1.230 (1)
C2—N1	1.341 (1)	C2—HC2	1.074 (2)
C3—C4	1.388 (1)	C4—HC4	1.092 (2)
C3—C7	1.492 (1)	C5—HC5	1.082 (3)
C4—C5	1.385 (1)	C6—HC6	1.077 (2)
C5—C6	1.383 (1)	N2—HN2A	1.000 (2)
C6—N1	1.338 (1)	N2—HN2B	1.015 (2)
C7—N2	1.337 (1)

C3—C2—N1	123.10 (8)	C3—C2—HC2	121.51 (19)
C2—C3—C4	118.03 (9)	N1—C2—HC2	115.36 (18)
C2—C3—C7	124.08 (8)	C3—C4—HC4	118.5 (2)
C4—C3—C7	117.87 (9)	C5—C4—HC4	122.0 (2)
C3—C4—C5	119.52 (10)	C4—C5—HC5	121.5 (3)
C4—C5—C6	118.27 (9)	C6—C5—HC5	120.2 (3)
C5—C6—N1	123.10 (9)	C5—C6—HC6	120.4 (2)
C3—C7—N2	117.81 (8)	N1—C6—HC6	116.5 (2)
C3—C7—O1	119.72 (10)	C7—N2—HN2A	121.3 (2)
N2—C7—O1	122.46 (11)	C7—N2—HN2B	118.5 (2)
C2—N1—C6	117.95 (9)

C2—C3—C4—C5	−1.7 (1)	C4—C3—C7—O1	21.0 (1)
C2—C3—C7—N2	23.0 (1)	C4—C5—C6—N1	−0.2 (2)
C2—C3—C7—O1	−157.6 (1)	C5—C6—N1—C2	−1.1 (1)
C3—C2—N1—C6	1.0 (1)	C7—C3—C4—C5	179.62 (9)
C3—C4—C5—C6	1.6 (2)	N1—C2—C3—C4	0.4 (1)
C4—C3—C7—N2	−158.45 (8)	N1—C2—C3—C7	178.98 (8)

Experimental details

	(NAD150X)	(NAD295X)	(NAD295N)
Crystal data
Chemical formula	C₆H₆N₂O	C₆H₆N₂O	C₆H₆N₂O
M_r	122.13	122.13	122.13
Crystal system, space group	Monoclinic, P2₁/c	Monoclinic, P2₁/c	Monoclinic, P2₁/c
Temperature (K)	150	295	295
a, b, c (Å)	3.877 (4), 15.60 (1), 9.375 (6)	3.975 (5), 15.632 (8), 9.422 (4)	3.975 (5), 15.632 (8), 9.422 (4)
β (°)	98.45 (7)	99.03 (7)	99.03 (7)
V (Å³)	560.8	578.2	578.2
Z	4	4	4
Radiation type	Mo Kα	Mo Kα	Neutron, λ = 1.005 (3) Å
µ (mm⁻¹)	0.10	0.10	0.83
Crystal size (mm)	0.70 × 0.70 × 0.60	0.80 × 0.70 × 0.60	6.0 × 4.0 × 4.0

Data collection
Diffractometer	Rigaku AFC5-RU200 diffractometer	Rigaku AFC5-RU200 diffractometer	Four-circle diffractometer
Absorption correction	–	–	–
No. of measured, independent and observed [F > 3σ(F)] reflections	6781, 6199, 4810	5771, 5246, 3471	1748, 1739, 1026
R_int	0.024	0.009	0.022
(sin θ/λ)_max (Å⁻¹)	1.153	1.116	0.704

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.054, 0.056, ?	0.057, 0.066, ?	0.060, 0.068, ?
No. of reflections	4810	3471	1026
No. of parameters	106	106	137
No. of restraints	?	?	?
H-atom treatment	Refxyz all from D-map	Refxyz all from D-map	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.47, −0.26	0.49, −0.18	?, ?

Computer programs: Rigaku/AFC5, MSC/AFC (MSC, 1988), 4CND software, MULTAN88(Main et al., 1988), Full-MATRIX LEAST-SQUARE, Full-matrix least-squares, KPPXRAY, EDCIF-J.

Table 3. Selected bond lengths and angles (Å, ° ) top

		X-ray diffraction	neutron diffraction
	150K	295K	295K
C2—C3	1.393 (1)	1.390 (1)	1.384 (1)
C2—N1	1.338 (1)	1.337 (1)	1.341 (1)
C3—C4	1.383 (1)	1.379 (1)	1.388 (1)
C3—C7	1.496 (1)	1.498 (1)	1.492 (1)
C4—C5	1.381 (1)	1.376 (1)	1.385 (1)
C5—C6	1.384 (1)	1.375 (2)	1,383 (1)
C6—N1	1.338 (1)	1.332 (1)	1.338 (1)
C7—N2	1.332 (1)	1.329 (1)	1.337 (1)
C7—O1	1.238 (1)	1.234 (1)	1.230 (1)
C2—HC2	0.928 (9)	0.93 (1)	1.074 (2)
C4—HC4	1.037 (9)	1.02 (1)	1.092 (2)
C5—HC5	0.93 (1)	0.93 (1)	1.082 (3)
C6—HC6	0.98 (1)	1.00 (1)	1.077 (2)
N2—HN2A	0.88 (1)	0.89 (1)	1.000 (2)
N2—HN2B	0.91 (1)	0.89 (1)	1.015 (2)
C3—C2—N1	123.01 (7)	123.25 (8)	123.10 (8)
C2—C3—C4	118.10 (5)	117.73 (7)	118.03 (9)
C2—C3—C7	123.81 (7)	123.76 (8)	124.08 (8)
C4—C3—C7	118.07 (7)	118.49 (7)	117.87 (9)
C3—C4—C5	119.62 (7)	119.75 (8)	119.52 (10)
C4—C5—C6	118.08 (8)	118.22 (9)	118.27 (9)
C5—C6—N1	123.55 (6)	123.69 (8)	123.10 (9)
C3—C7—N2	117.70 (6)	117.92 (6)	117.81 (8)
C3—C7—O1	119.16 (7)	119.13 (8)	119.72 (10)
N2—C7—O1	123.13 (6)	122.96 (7)	122.46 (11)
C2—N1—C6	117.59 (7)	117.31 (7)	117.95 (9)
C3—C2—HC2	124.3 (6)	119.1 (6)	121.51 (19)
N1—C2—HC2	112.5 (6)	117.3 (6)	115.36 (18)
C3—C4—HC4	116.6 (6)	117.9 (7)	118.45 (21)
C5—C4—HC4	123.8 (6)	122.4 (7)	122.01 (24)
C4—C5—HC5	118.6 (6)	121.2 (6)	121.48 (25)
C6—C5—HC5	123.1 (6)	120.6 (6)	120.24 (25)
C5—C6—HC6	121.9 (6)	123.9 (7)	120.36 (24)
N1—C6—HC6	114.5 (6)	112.3 (6)	116.54 (21)
C7—N2—HN2A	121.6 (7)	120.1 (7)	121.25 (21)
C7—N2—HN2B	117.2 (6)	122.5 (6)	118.45 (21)

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