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The title compound, C9H12N2O, crystallizes in a triclinic unit cell, with two crystallographically independent mol­ecules in the asymmetric unit. The two independent mol­ecules adopt different modes of packing. One type of mol­ecule is arranged in infinite columns, while the other type packs as dimers, forming spacers between the parallel columns. Each type of mol­ecule is arranged in pairs related by inversion centers. The distances between potential reaction centers are 3.395 (2), 3.457 (2) and 3.522 (2) Å. As a result of the symmetry of the pairs and the close distances between the potential photoreactive centers, it is expected that the dimer will be the anti-trans isomer.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102001087/oa1127sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270102001087/oa1127Isup2.hkl
Contains datablock I

CCDC reference: 182998

Comment top

There is confusion regarding the solid-state photodimerization of some pyrazin-2(1H)-ones. The present study intends to clear up some of the missinterpratations regarding the photochemical product. It was reported (Nishio et al., 1980) that 1-methyl-5,6-diphenylpyrazin-2-one and 1-methyl-5,6,7,8-tetrahydro-2(1H)-quinoxalinone [(Ia) and (Ib), respectively] were inert to photolysis in benzene or methanol solution; however, irradiation of the methyl derivative (Ia) in the solid state gave the [4 + 4] dimer. In principle, four different cyclodimers may be anticipated, as shown in the Scheme below. The solid-state photoreaction however, led to a single isomer, assigned by the authors as the anti–trans dimer. The solid-state photochemical dimerization of 1-methyl-5,6-diphenylpyrazin-2-one, (I), was discussed in a publication by Kaftoy (1984). The compound crystallizes in two different polymorphic forms, viz. a light-sensitive and a light-stable form. The crystal of the light-sensitive modification is chiral (space group P21), with two crystallographically independent molecules in the asymmetric unit. The two molecules related by pseudo-twofold symmetry. The mutual orientation and the short distances between the two molecules suggest that the irradiation of the crystal will lead to the formation of the syn–trans isomer. The crystal structure of the product proves that the expectation was correct. These results led Nishio et al. (Nishio, Nakajima, Kondo, Omote & Kaftory, 1984; Nishio, Nakajima, Kondo & Omote, 1984) to publish a paper with a structural revision of the photoproduct of (Ia). Unfortunately, Nishio et al. also revised the structure of the photoproduct of (Ib) and suggested that it should also be the syn–trans isomer. The crystal structure of (Ib), which is described here, shows undoubtedly that irradiation of the crystalline material should lead to the anti–trans isomer.

The title compound crystallizes in the triclinic unit cell (space group P1), with two crystallographically independent molecules. The packing of the molecules in the unit cell is very special (see Fig. 1). Molecules of A are packed in columns running along the a axis, while molecules of B are arranged in pairs inclined by 62.8 (1)° to the columns and blocked by them. As a result, there are three different pairs that may be photochemically dimerized. The two B molecules are related by an inversion center (see Fig. 2), with distances between the reaction centers (C2a···C4a) of 3.395 (2) Å. The molecules of type A that are arranged in infinite columns show two different pairs (see Fig. 3). In each pair, the molecules are related by inversion centers and therefore the photodeimer is expected to be the anti–trans isomer. The distances between the reacting centers of the two different pairs are 3.457 (2) and 3.522 (2) Å. In all the pairs mentioned above, the distances between the reacting centers are much smaller than the upper limit of the distances between potential photoreactive centers that enable the execution of solid-state photodimerization, discussed by Schmidt (1971). In Table 1, the bond lengths and angles of the pyrazinone ring of the present work are compared with those found in 1-methyl-, (Ia), and 1-ethyl-5,6-diphenylpyrazin-2(1H)-one, (Ic), in 1-(2-hydroxyethyl)-5,6-diphenylpyrazin-2(1H)-one (TANNEB; Mori et al. 1992), in 1-(3-hydroxpropyl)-5,6-diphenylpyrazin-2(1H)-one (TANNIF; Kaftory, 1984) [the codes are Cambridge Structural Database (2001) refcodes]. Some bond angles should be noted. The inner-ring bond angle at the carbonyl C atom (C1) is significantly smaller (113.7–114.9°) than that expected for a Csp2 atom. The calculated average value obtained from 141 compounds possessing the pyridone moiety taken from the Cambridge Structural Database (2001) is 115.3(1.3)°. Also, to be noted is the significantly larger inner-ring bond angle at C4 (124.5–126.2°) compared with that at C3 (120.8–122.8°). The calculated average values for the same bond angles in pyridones are 121.0 (14) and 118.9 (13)°, respectively. There is a significant difference between the outer-ring bond angles at C1 (120.6–122.2° for O1—C1—N1 compared with 123.5–124.9° for O1—C1—C4). Similar differences were found in the geometry of pyridones where the average of the comparable bond angles are 119.6(1.2) and 125.1(1.3)°.

Experimental top

The title compound was synthesized according to the procedure of Nishio (1985).

Refinement top

The H atoms were located in a difference Fourier map. The coordinates and isotropic displacement parameters were refined [C—H = 0.96 (3)–1.05 (3) Å].

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997).

Figures top
[Figure 1] Fig. 1. View of the packing of (Ib) in the unit cell (ORTEP-3; Farrugia, 1997).
[Figure 2] Fig. 2. The dimer formed by molecules of A (ORTEP-3; Farrugia, 1997).
[Figure 3] Fig. 3. The two possible dimers formed by molecules of B (ORTEP-3; Farrugia, 1997).
(I) top
Crystal data top
C9H12N2OZ = 4
Mr = 164.21F(000) = 352
Triclinic, P1Dx = 1.326 Mg m3
a = 6.791 (1) ÅMo Kα radiation, λ = 0.71073 Å
b = 11.170 (2) ÅCell parameters from 3833 reflections
c = 11.246 (2) Åθ = 1.7–26.4°
α = 93.75 (3)°µ = 0.09 mm1
β = 97.13 (3)°T = 140 K
γ = 102.56 (2)°Plate, colorless
V = 822.4 (3) Å30.20 × 0.15 × 0.08 mm
Data collection top
Nonius KappaCCD
diffractometer
2056 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.055
Graphite monochromatorθmax = 27.8°, θmin = 1.8°
ϕ and ω scansh = 08
8459 measured reflectionsk = 1414
3751 independent reflectionsl = 1414
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.055All H-atom parameters refined
wR(F2) = 0.169 w = 1/[σ2(Fo2) + (0.1P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.91(Δ/σ)max = 0.002
3751 reflectionsΔρmax = 0.27 e Å3
314 parametersΔρmin = 0.25 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.060 (9)
Crystal data top
C9H12N2Oγ = 102.56 (2)°
Mr = 164.21V = 822.4 (3) Å3
Triclinic, P1Z = 4
a = 6.791 (1) ÅMo Kα radiation
b = 11.170 (2) ŵ = 0.09 mm1
c = 11.246 (2) ÅT = 140 K
α = 93.75 (3)°0.20 × 0.15 × 0.08 mm
β = 97.13 (3)°
Data collection top
Nonius KappaCCD
diffractometer
2056 reflections with I > 2σ(I)
8459 measured reflectionsRint = 0.055
3751 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0550 restraints
wR(F2) = 0.169All H-atom parameters refined
S = 0.91Δρmax = 0.27 e Å3
3751 reflectionsΔρmin = 0.25 e Å3
314 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
O1A0.2239 (3)0.17856 (15)1.11151 (15)0.0375 (5)
N1A0.2699 (3)0.02797 (17)1.08888 (15)0.0252 (5)
N2A0.2279 (3)0.02539 (18)0.84358 (17)0.0309 (5)
C1A0.2356 (3)0.0945 (2)1.0443 (2)0.0270 (5)
C2A0.2766 (3)0.12215 (19)1.01429 (19)0.0240 (5)
C3A0.2582 (3)0.0945 (2)0.89320 (19)0.0268 (5)
C4A0.2171 (4)0.1128 (2)0.9151 (2)0.0293 (6)
C5A0.3014 (5)0.0536 (3)1.2208 (2)0.0382 (7)
C6A0.2737 (4)0.1916 (2)0.8069 (2)0.0369 (6)
C7A0.3755 (5)0.3187 (2)0.8697 (3)0.0424 (7)
C8A0.2731 (4)0.3420 (2)0.9791 (3)0.0405 (7)
C9A0.3055 (4)0.2518 (2)1.0712 (2)0.0334 (6)
O1B0.2489 (3)0.63679 (14)0.74832 (15)0.0386 (5)
N1B0.0070 (3)0.45958 (16)0.68387 (15)0.0251 (5)
N2B0.2531 (3)0.39788 (17)0.52403 (16)0.0291 (5)
C1B0.1914 (3)0.5396 (2)0.6813 (2)0.0275 (5)
C2B0.0592 (3)0.35216 (19)0.60677 (19)0.0253 (5)
C3B0.0674 (3)0.3220 (2)0.53033 (19)0.0265 (5)
C4B0.3102 (4)0.5000 (2)0.5948 (2)0.0301 (6)
C5B0.1193 (4)0.4905 (3)0.7740 (3)0.0371 (6)
C6B0.0132 (4)0.2033 (2)0.4490 (2)0.0323 (6)
C7B0.1658 (4)0.1123 (2)0.4837 (2)0.0359 (6)
C8B0.3362 (4)0.1764 (2)0.5046 (2)0.0344 (6)
C9B0.2681 (4)0.2749 (2)0.6111 (2)0.0295 (6)
H4A10.204 (4)0.197 (2)0.882 (2)0.041 (7)*
H5A10.164 (5)0.055 (3)1.252 (3)0.074 (10)*
H5A20.346 (4)0.015 (2)1.255 (2)0.045 (8)*
H5A30.395 (5)0.132 (3)1.245 (3)0.062 (9)*
H6A10.134 (4)0.189 (2)0.768 (2)0.050 (8)*
H6A20.351 (4)0.171 (2)0.742 (2)0.045 (7)*
H7A10.525 (5)0.319 (2)0.902 (3)0.059 (9)*
H7A20.367 (5)0.384 (3)0.814 (3)0.062 (9)*
H8A10.117 (5)0.329 (2)0.955 (2)0.048 (8)*
H8A20.325 (4)0.427 (3)1.016 (2)0.051 (8)*
H9A10.212 (4)0.251 (2)1.137 (2)0.046 (7)*
H9A20.439 (4)0.273 (2)1.117 (2)0.040 (7)*
H4B10.447 (5)0.558 (3)0.590 (2)0.058 (9)*
H5B10.020 (5)0.553 (3)0.831 (3)0.058 (9)*
H5B20.229 (5)0.524 (3)0.733 (3)0.062 (9)*
H5B30.173 (5)0.416 (3)0.812 (3)0.069 (10)*
H6B10.145 (4)0.170 (2)0.4508 (19)0.027 (6)*
H6B20.014 (4)0.226 (2)0.368 (2)0.042 (7)*
H7B10.212 (4)0.042 (2)0.418 (2)0.042 (7)*
H7B20.123 (4)0.071 (2)0.561 (2)0.039 (7)*
H8B10.372 (4)0.215 (2)0.431 (2)0.043 (7)*
H8B20.463 (4)0.119 (2)0.522 (2)0.046 (7)*
H9B10.363 (4)0.331 (2)0.611 (2)0.034 (7)*
H9B20.259 (3)0.241 (2)0.689 (2)0.028 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O1A0.0346 (10)0.0372 (10)0.0454 (10)0.0118 (8)0.0099 (8)0.0178 (8)
N1A0.0229 (10)0.0304 (10)0.0220 (9)0.0047 (8)0.0054 (7)0.0017 (8)
N2A0.0277 (12)0.0358 (11)0.0291 (10)0.0083 (9)0.0045 (8)0.0022 (9)
C1A0.0171 (12)0.0301 (12)0.0346 (13)0.0068 (10)0.0039 (9)0.0045 (10)
C2A0.0184 (12)0.0262 (12)0.0269 (11)0.0048 (9)0.0020 (9)0.0017 (9)
C3A0.0219 (12)0.0314 (13)0.0281 (12)0.0080 (10)0.0029 (9)0.0040 (10)
C4A0.0242 (13)0.0308 (13)0.0337 (13)0.0094 (10)0.0046 (10)0.0023 (11)
C5A0.0438 (17)0.0495 (17)0.0202 (12)0.0106 (14)0.0011 (11)0.0024 (12)
C6A0.0377 (16)0.0421 (15)0.0337 (14)0.0120 (13)0.0063 (12)0.0127 (11)
C7A0.0408 (18)0.0367 (15)0.0552 (17)0.0127 (13)0.0114 (13)0.0218 (13)
C8A0.0334 (16)0.0296 (14)0.0600 (18)0.0070 (12)0.0119 (13)0.0067 (13)
C9A0.0294 (15)0.0309 (13)0.0387 (14)0.0057 (11)0.0060 (12)0.0029 (11)
O1B0.0393 (11)0.0296 (9)0.0413 (10)0.0023 (8)0.0005 (8)0.0063 (8)
N1B0.0266 (11)0.0237 (10)0.0253 (10)0.0064 (8)0.0050 (8)0.0005 (8)
N2B0.0282 (11)0.0296 (10)0.0302 (10)0.0056 (9)0.0083 (8)0.0026 (8)
C1B0.0244 (13)0.0262 (12)0.0307 (12)0.0059 (10)0.0006 (9)0.0014 (10)
C2B0.0267 (13)0.0245 (11)0.0247 (11)0.0062 (10)0.0028 (9)0.0037 (9)
C3B0.0283 (13)0.0254 (12)0.0269 (12)0.0063 (10)0.0063 (9)0.0049 (9)
C4B0.0261 (14)0.0295 (13)0.0351 (13)0.0058 (11)0.0057 (10)0.0054 (11)
C5B0.0367 (16)0.0384 (15)0.0372 (14)0.0101 (13)0.0114 (12)0.0062 (13)
C6B0.0423 (16)0.0300 (13)0.0257 (13)0.0095 (11)0.0076 (11)0.0005 (10)
C7B0.0469 (17)0.0256 (13)0.0323 (13)0.0046 (12)0.0046 (11)0.0031 (11)
C8B0.0321 (15)0.0300 (13)0.0363 (14)0.0011 (11)0.0023 (11)0.0005 (11)
C9B0.0288 (14)0.0301 (13)0.0298 (13)0.0058 (11)0.0043 (10)0.0068 (10)
Geometric parameters (Å, º) top
O1A—C1A1.239 (3)O1B—C1B1.239 (2)
N1A—C2A1.384 (3)N1B—C1B1.376 (3)
N1A—C1A1.386 (3)N1B—C2B1.388 (3)
N1A—C5A1.472 (3)N1B—C5B1.477 (3)
N2A—C4A1.301 (3)N2B—C4B1.303 (3)
N2A—C3A1.379 (3)N2B—C3B1.371 (3)
C1A—C4A1.440 (3)C1B—C4B1.444 (3)
C2A—C3A1.361 (3)C2B—C3B1.365 (3)
C2A—C9A1.507 (3)C2B—C9B1.500 (3)
C3A—C6A1.497 (3)C3B—C6B1.508 (3)
C4A—H4A10.97 (2)C4B—H4B11.02 (3)
C5A—H5A11.04 (4)C5B—H5B10.99 (3)
C5A—H5A20.97 (3)C5B—H5B20.98 (3)
C5A—H5A30.96 (3)C5B—H5B30.99 (3)
C6A—C7A1.520 (4)C6B—C7B1.515 (4)
C6A—H6A10.99 (3)C6B—H6B11.04 (2)
C6A—H6A21.00 (3)C6B—H6B20.97 (3)
C7A—C8A1.522 (4)C7B—C8B1.521 (4)
C7A—H7A11.03 (3)C7B—H7B11.01 (3)
C7A—H7A21.00 (3)C7B—H7B21.05 (3)
C8A—C9A1.520 (4)C8B—C9B1.526 (3)
C8A—H8A11.04 (3)C8B—H8B10.99 (3)
C8A—H8A20.98 (3)C8B—H8B21.01 (3)
C9A—H9A11.04 (3)C9B—H9B11.00 (3)
C9A—H9A20.96 (3)C9B—H9B20.98 (2)
C2A—N1A—C1A122.27 (17)C1B—N1B—C2B122.10 (19)
C2A—N1A—C5A121.24 (19)C1B—N1B—C5B117.58 (19)
C1A—N1A—C5A116.5 (2)C2B—N1B—C5B120.3 (2)
C4A—N2A—C3A118.63 (19)C4B—N2B—C3B118.6 (2)
O1A—C1A—N1A121.9 (2)O1B—C1B—N1B122.2 (2)
O1A—C1A—C4A124.4 (2)O1B—C1B—C4B123.5 (2)
N1A—C1A—C4A113.7 (2)N1B—C1B—C4B114.28 (19)
C3A—C2A—N1A119.07 (19)C3B—C2B—N1B118.8 (2)
C3A—C2A—C9A122.6 (2)C3B—C2B—C9B123.1 (2)
N1A—C2A—C9A118.29 (19)N1B—C2B—C9B118.1 (2)
C2A—C3A—N2A121.3 (2)C2B—C3B—N2B121.7 (2)
C2A—C3A—C6A122.3 (2)C2B—C3B—C6B122.3 (2)
N2A—C3A—C6A116.35 (19)N2B—C3B—C6B116.0 (2)
N2A—C4A—C1A124.9 (2)N2B—C4B—C1B124.5 (2)
N2A—C4A—H4A1119.5 (15)N2B—C4B—H4B1119.6 (15)
C1A—C4A—H4A1115.4 (15)C1B—C4B—H4B1115.9 (15)
N1A—C5A—H5A1110.8 (17)N1B—C5B—H5B1102.2 (17)
N1A—C5A—H5A2107.9 (15)N1B—C5B—H5B2108.5 (18)
H5A1—C5A—H5A2105 (2)H5B1—C5B—H5B2112 (2)
N1A—C5A—H5A3110.2 (19)N1B—C5B—H5B3108.7 (17)
H5A1—C5A—H5A3109 (2)H5B1—C5B—H5B3112 (2)
H5A2—C5A—H5A3114 (2)H5B2—C5B—H5B3112 (3)
C3A—C6A—C7A111.8 (2)C3B—C6B—C7B112.1 (2)
C3A—C6A—H6A1107.3 (16)C3B—C6B—H6B1106.9 (12)
C7A—C6A—H6A1111.2 (15)C7B—C6B—H6B1113.6 (13)
C3A—C6A—H6A2109.7 (15)C3B—C6B—H6B2105.8 (14)
C7A—C6A—H6A2110.0 (15)C7B—C6B—H6B2112.3 (15)
H6A1—C6A—H6A2107 (2)H6B1—C6B—H6B2105 (2)
C6A—C7A—C8A109.2 (2)C6B—C7B—C8B110.1 (2)
C6A—C7A—H7A1108.1 (15)C6B—C7B—H7B1108.6 (15)
C8A—C7A—H7A1106.5 (16)C8B—C7B—H7B1112.1 (15)
C6A—C7A—H7A2110.9 (16)C6B—C7B—H7B2111.4 (14)
C8A—C7A—H7A2110.2 (17)C8B—C7B—H7B2109.8 (14)
H7A1—C7A—H7A2112 (3)H7B1—C7B—H7B2104.7 (19)
C9A—C8A—C7A110.6 (2)C7B—C8B—C9B110.8 (2)
C9A—C8A—H8A1106.9 (15)C7B—C8B—H8B1107.9 (15)
C7A—C8A—H8A1110.7 (14)C9B—C8B—H8B1109.5 (14)
C9A—C8A—H8A2109.6 (16)C7B—C8B—H8B2113.5 (15)
C7A—C8A—H8A2111.2 (17)C9B—C8B—H8B2107.0 (14)
H8A1—C8A—H8A2108 (2)H8B1—C8B—H8B2108 (2)
C2A—C9A—C8A112.5 (2)C2B—C9B—C8B111.7 (2)
C2A—C9A—H9A1108.9 (14)C2B—C9B—H9B1107.6 (14)
C8A—C9A—H9A1112.6 (15)C8B—C9B—H9B1110.6 (13)
C2A—C9A—H9A2106.3 (15)C2B—C9B—H9B2105.0 (14)
C8A—C9A—H9A2113.1 (16)C8B—C9B—H9B2113.4 (13)
H9A1—C9A—H9A2103 (2)H9B1—C9B—H9B2108.3 (19)
C2A—N1A—C1A—O1A177.8 (2)C2B—N1B—C1B—O1B178.5 (2)
C5A—N1A—C1A—O1A2.8 (3)C5B—N1B—C1B—O1B2.6 (3)
C2A—N1A—C1A—C4A2.6 (3)C2B—N1B—C1B—C4B1.7 (3)
C5A—N1A—C1A—C4A176.8 (2)C5B—N1B—C1B—C4B177.2 (2)
C1A—N1A—C2A—C3A3.1 (3)C1B—N1B—C2B—C3B3.4 (3)
C5A—N1A—C2A—C3A176.3 (2)C5B—N1B—C2B—C3B175.5 (2)
C1A—N1A—C2A—C9A177.3 (2)C1B—N1B—C2B—C9B176.2 (2)
C5A—N1A—C2A—C9A3.3 (3)C5B—N1B—C2B—C9B4.9 (3)
N1A—C2A—C3A—N2A1.7 (3)N1B—C2B—C3B—N2B3.1 (3)
C9A—C2A—C3A—N2A178.7 (2)C9B—C2B—C3B—N2B176.5 (2)
N1A—C2A—C3A—C6A177.1 (2)N1B—C2B—C3B—C6B176.2 (2)
C9A—C2A—C3A—C6A2.5 (3)C9B—C2B—C3B—C6B4.2 (4)
C4A—N2A—C3A—C2A0.0 (3)C4B—N2B—C3B—C2B1.2 (3)
C4A—N2A—C3A—C6A178.8 (2)C4B—N2B—C3B—C6B178.1 (2)
C3A—N2A—C4A—C1A0.4 (3)C3B—N2B—C4B—C1B0.5 (3)
O1A—C1A—C4A—N2A179.6 (2)O1B—C1B—C4B—N2B179.6 (2)
N1A—C1A—C4A—N2A0.9 (3)N1B—C1B—C4B—N2B0.2 (3)
C2A—C3A—C6A—C7A18.0 (3)C2B—C3B—C6B—C7B13.7 (3)
N2A—C3A—C6A—C7A160.8 (2)N2B—C3B—C6B—C7B165.6 (2)
C3A—C6A—C7A—C8A50.3 (3)C3B—C6B—C7B—C8B46.6 (3)
C6A—C7A—C8A—C9A64.2 (3)C6B—C7B—C8B—C9B63.9 (3)
C3A—C2A—C9A—C8A10.4 (3)C3B—C2B—C9B—C8B11.8 (3)
N1A—C2A—C9A—C8A170.0 (2)N1B—C2B—C9B—C8B167.8 (2)
C7A—C8A—C9A—C2A43.3 (3)C7B—C8B—C9B—C2B45.0 (3)

Experimental details

Crystal data
Chemical formulaC9H12N2O
Mr164.21
Crystal system, space groupTriclinic, P1
Temperature (K)140
a, b, c (Å)6.791 (1), 11.170 (2), 11.246 (2)
α, β, γ (°)93.75 (3), 97.13 (3), 102.56 (2)
V3)822.4 (3)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.20 × 0.15 × 0.08
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
8459, 3751, 2056
Rint0.055
(sin θ/λ)max1)0.657
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.169, 0.91
No. of reflections3751
No. of parameters314
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.27, 0.25

Computer programs: COLLECT (Nonius, 1998), DENZO-SMN (Otwinowski & Minor, 1997), DENZO-SMN, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997).

Comparison of bond lengths (Å) and angles (°) in pyrazinones top
(Ib)a(Ib)(Ia)b(Ia)(Ic)cTANNEBdTANNIFe
Molecule AMolecule BMolecule AMolecule B
O1—C11.239 (3)1.239 (2)1.228 (4)1.235 (3)1.233 (4)1.2391.226
N1—C11.386 (3)1.376 (3)1.393 (4)1.389 (4)1.385 (4)1.3861.391
N1—C21.384 (3)1.388 (3)1.391 (4)1.391 (3)1.378 (3)1.3831.386
N2—C41.301 (3)1.303 (3)1.291 (4)1.297 (4)1.299 (4)1.2901.297
N2—C31.379 (3)1.371 (3)1.361 (3)1.362 (4)1.372 (4)1.3841.375
C1—C41.440 (3)1.444 (3)1.437 (4)1.440 (4)1.437 (4)1.4281.439
C2—C31.361 (3)1.365 (3)1.361 (3)1.362 (4)1.372 (4)1.3611.380
C1A—N1A—C2A122.3 (2)122.1 (2)121.2 (3)121.9 (3)121.9 (2)120.8121.6
C4A—N2A—C3A118.6 (2)118.6 (2)117.6 (3)118.3 (3)118.0 (2)118.6118.9
O1A—C1A—N1A121.9 (2)122.2 (2)121.8 (3)122.2 (3)121.4 (3)120.6121.8
O1A—C1A—C4A124.4 (2)123.5 (2)124.5 (3)124.1 (3)124.6 (3)124.6124.3
N1A—C1A—C4A113.7 (2)114.3 (2)113.7 (3)113.8 (3)114.0 (2)114.9113.8
C3A—C2A—N1A119.1 (2)118.8 (2)119.4 (2)118.8 (2)119.2 (2)119.9119.4
C2A—C3A—N2A121.3 (2)121.7 (2)121.7 (2)121.7 (3)121.4 (2)120.8120.6
N2A—C4A—C1A124.9 (2)124.5 (2)126.2 (2)125.3 (2)125.4 (3)125.0125.4
Notes: (a) present work; (b) (Ia) is 1-methyl-5,6-diphenylpyrazin-2(1H)-one; (c) (Ic) is 1-ethyl-5,6-diphenylpyrazin-2(1H)-one; (d) Mori et al. (1992); (e) Kaftory (1984).
 

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