2-Amino-6-eth­oxy-4-methyl­pyridine-3,5-dicarbonitrile

In the title compound, C₁₀H₁₀N₄O, the crystal packing is stabilized by inter­molecular N—H...N hydrogen bonds between adjacent pyridine rings, resulting in a two-dimensional layer structure. The H atoms of the 4-methyl group are disordered [site occupation factors 0.643 (14) and 0.357 (14)].

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.035
• wR factor = 0.101
• Data-to-parameter ratio = 15.3

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    C2     -   C6      ..       8.18 su
PLAT230_ALERT_2_B Hirshfeld Test Diff for    C4     -   C7      ..       8.51 su

Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.71 mm
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)       3000 Deg.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C2     -   C6     ...       1.43 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C4     -   C7     ...       1.43 Ang.

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

In the title compound the pyridine ring is essentially planar and the ethoxy group lies within the molecule plane (C9—O1—C5—N1 2.04 (14), C5—O1—C9—C10 - 170.90 (9)°) with the methylene protons in staggered geometry with respect to the pyridine N atom (N1). The amino group is almost planar with the protons in eclipsed geometry with respect to the pyridine ring, indicating conjugation of the p-type lone-pair of N2 with the aromatic ring. The methyl group of I was found to be disordered. The H atoms were split over two positions with occupancy factors refined to 0.643 (14) and 0.357 (14) (Fig. 1).

In the crystal structure, the molecules of I are held together by the formation of four intermolecular N—H···N hydrogen bonds per molecule within the pyridine-ring plane, leading to a two-dimensional layered network. Only weak van der Waals interactions can be assumed between the adjacent layers (Fig.2).

Related literature

For an alternative preparation of the title compound, see: Uray & Kriessmann (1984); Alberola et al. (1967). For a review describing the preparation, reactions and applications of substituted pyridine derivatives, see: Spitzner (2005).

S2. Experimental

The title compound is described in the literature (Uray & Kriessmann 1984; Alberola et al., 1967) and was unintentionally obtained as a by-product of an attempted reaction of malonitrile with cyanur chloride in an ethanol/sodium ethanolate solution in 12% yield. Crystallization from a n-heptane/ethyl acetate solution at ambient temperature gave colourless X-ray quality crystals. ¹H-NMR (Acetone-d₆, 25°C): δ = 1.34 (t, 3H, OCH₂CH₃), 2.48 (s, 3H, CH₃), (q, 2H, OCH₂CH₃).

S3. Refinement

H atoms bonded to N2 were located in a difference map and refined freely. Other H atoms were positioned geometrically and refined using a riding model, with C—H = 0.98 (C8, C10)or 0.99 Å (C9) and with U_iso(H) = 1.5 times U_eq(C) (methyl groups) or with U_iso(H) = 1.2 times U_eq(C) (methylene group). Torsion angles of all methyl groups were allowed to refine. For the methyl group at C8 ideal disorder was assumed, with two positions rotated from each other by 60°. The occupancy factors of each part were refined freely (0.643 (14)/0.357 (14)).

Computing details

Data collection: APEX2 (Bruker, 2003); cell refinement: APEX2 (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. Molecular structure of (I), showing the atomic numbering scheme and displacement ellipsoids drawn at the 50% probability level. Both components of the disordered methyl group are shown.
	Fig. 2. Part of the packing diagram of (I). Unique N—H···N interactions represented by dashed lines are shown for one molecule of (I). Symmetry code: (i) -x + 2, -y + 2, -z + 1; (ii) x + 1, y - 1, z.

2-Amino-6-ethoxy-4-methylpyridine-3,5-dicarbonitrile

Crystal data

C10H10N4O	Z = 2
Mr = 202.22	F(000) = 212
Triclinic, P1	Dx = 1.364 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.5050 (11) Å	Cell parameters from 4290 reflections
b = 7.3500 (15) Å	θ = 5.6–60.3°
c = 12.385 (3) Å	µ = 0.09 mm^−1
α = 86.27 (3)°	T = 173 K
β = 81.33 (3)°	Needle, colourless
γ = 84.19 (3)°	0.71 × 0.08 × 0.06 mm
V = 492.22 (18) Å^3

Data collection

Bruker-Nonius Apex X8 CCD diffractometer	2247 independent reflections
Radiation source: sealed tube	1809 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
ω scans	θmax = 27.5°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −7→7
Tmin = 0.936, Tmax = 0.994	k = −9→9
9312 measured reflections	l = −15→16

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.101	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0579P)^2 + 0.0638P] where P = (Fo^2 + 2Fc^2)/3
2247 reflections	(Δ/σ)max < 0.001
147 parameters	Δρmax = 0.27 e Å^−3
0 restraints	Δρmin = −0.24 e Å^−3

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	Occ. (<1)
O1	−0.07335 (13)	0.94702 (10)	0.87234 (6)	0.0251 (2)
C2	0.48464 (18)	1.09638 (14)	0.64233 (8)	0.0219 (2)
C4	0.09244 (18)	1.17003 (14)	0.74881 (9)	0.0220 (2)
N1	0.30361 (15)	0.86890 (12)	0.77104 (7)	0.0224 (2)
N2	0.67687 (17)	0.78992 (13)	0.66985 (8)	0.0271 (2)
H2	0.811 (3)	0.8114 (19)	0.6238 (12)	0.035 (4)*
H1	0.674 (3)	0.686 (2)	0.7068 (12)	0.037 (4)*
N3	0.84730 (17)	1.18521 (13)	0.49830 (8)	0.0305 (2)
N4	−0.28058 (18)	1.40401 (14)	0.79863 (8)	0.0325 (2)
C1	0.48938 (18)	0.91833 (14)	0.69423 (8)	0.0214 (2)
C3	0.28386 (19)	1.22428 (14)	0.67055 (9)	0.0227 (2)
C5	0.11391 (18)	0.99004 (14)	0.79666 (8)	0.0211 (2)
C6	0.68578 (19)	1.14525 (14)	0.56238 (9)	0.0240 (2)
C7	−0.11812 (19)	1.29557 (15)	0.77955 (9)	0.0243 (2)
C8	0.2722 (2)	1.41415 (15)	0.61911 (10)	0.0311 (3)
H3A	0.1455	1.4285	0.5707	0.047*	0.643 (14)
H4A	0.4328	1.4356	0.5766	0.047*	0.643 (14)
H5A	0.2307	1.5028	0.6763	0.047*	0.643 (14)
H5B	0.3938	1.4828	0.6451	0.047*	0.357 (14)
H4B	0.1066	1.4756	0.6391	0.047*	0.357 (14)
H3B	0.3086	1.4084	0.5394	0.047*	0.357 (14)
C9	−0.0559 (2)	0.76583 (15)	0.92725 (9)	0.0273 (3)
H9	0.0733	0.7559	0.9755	0.033*
H10	−0.0137	0.6704	0.8729	0.033*
C10	−0.3038 (2)	0.74272 (17)	0.99326 (10)	0.0324 (3)
H11	−0.3475	0.8424	1.0435	0.049*
H12	−0.2976	0.6250	1.0352	0.049*
H13	−0.4281	0.7456	0.9441	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0256 (4)	0.0216 (4)	0.0255 (4)	−0.0024 (3)	0.0028 (3)	0.0048 (3)
C2	0.0232 (5)	0.0204 (5)	0.0219 (5)	−0.0042 (4)	−0.0022 (4)	0.0016 (4)
C4	0.0235 (5)	0.0195 (5)	0.0225 (5)	−0.0018 (4)	−0.0031 (4)	0.0009 (4)
N1	0.0244 (4)	0.0196 (4)	0.0224 (5)	−0.0025 (3)	−0.0019 (4)	0.0027 (3)
N2	0.0252 (5)	0.0208 (5)	0.0317 (5)	0.0012 (4)	0.0022 (4)	0.0048 (4)
N3	0.0280 (5)	0.0267 (5)	0.0331 (6)	−0.0010 (4)	0.0031 (4)	0.0055 (4)
N4	0.0318 (5)	0.0253 (5)	0.0365 (6)	0.0014 (4)	0.0028 (4)	0.0027 (4)
C1	0.0227 (5)	0.0210 (5)	0.0210 (5)	−0.0029 (4)	−0.0042 (4)	−0.0007 (4)
C3	0.0257 (5)	0.0200 (5)	0.0225 (5)	−0.0030 (4)	−0.0037 (4)	0.0013 (4)
C5	0.0222 (5)	0.0217 (5)	0.0197 (5)	−0.0043 (4)	−0.0031 (4)	0.0006 (4)
C6	0.0258 (5)	0.0199 (5)	0.0259 (6)	−0.0008 (4)	−0.0042 (4)	0.0010 (4)
C7	0.0277 (5)	0.0218 (5)	0.0229 (5)	−0.0054 (4)	−0.0014 (4)	0.0028 (4)
C8	0.0311 (5)	0.0217 (5)	0.0363 (7)	−0.0005 (4)	0.0037 (5)	0.0082 (5)
C9	0.0296 (5)	0.0225 (5)	0.0281 (6)	−0.0038 (4)	−0.0014 (4)	0.0077 (4)
C10	0.0313 (6)	0.0339 (6)	0.0302 (6)	−0.0085 (5)	0.0017 (5)	0.0071 (5)

Geometric parameters (Å, º)

O1—C5	1.3332 (13)	N4—C7	1.1435 (15)
O1—C9	1.4564 (13)	C3—C8	1.4954 (15)
C2—C3	1.3941 (15)	C8—H3A	0.9800
C2—C1	1.4195 (15)	C8—H4A	0.9800
C2—C6	1.4280 (15)	C8—H5A	0.9800
C4—C3	1.3913 (15)	C8—H5B	0.9800
C4—C5	1.4152 (15)	C8—H4B	0.9800
C4—C7	1.4269 (15)	C8—H3B	0.9800
N1—C5	1.3163 (14)	C9—C10	1.5008 (15)
N1—C1	1.3490 (14)	C9—H9	0.9900
N2—C1	1.3391 (14)	C9—H10	0.9900
N2—H2	0.883 (15)	C10—H11	0.9800
N2—H1	0.865 (16)	C10—H12	0.9800
N3—C6	1.1474 (14)	C10—H13	0.9800
C5—O1—C9	117.88 (8)	C3—C8—H3A	109.5
C3—C2—C1	119.74 (10)	C3—C8—H4A	109.5
C3—C2—C6	120.02 (10)	C3—C8—H5A	109.5
C1—C2—C6	120.23 (10)	C3—C8—H5B	109.5
C3—C4—C5	118.45 (10)	C3—C8—H4B	109.5
C3—C4—C7	119.89 (10)	H5B—C8—H4B	109.5
C5—C4—C7	121.66 (10)	C3—C8—H3B	109.5
C5—N1—C1	118.29 (9)	H5B—C8—H3B	109.5
C1—N2—H2	122.8 (9)	H4B—C8—H3B	109.5
C1—N2—H1	118.2 (10)	O1—C9—C10	106.66 (9)
H2—N2—H1	118.5 (14)	O1—C9—H9	110.4
N2—C1—N1	116.17 (10)	C10—C9—H9	110.4
N2—C1—C2	122.23 (10)	O1—C9—H10	110.4
N1—C1—C2	121.59 (10)	C10—C9—H10	110.4
C4—C3—C2	117.85 (10)	H9—C9—H10	108.6
C4—C3—C8	120.51 (10)	C9—C10—H11	109.5
C2—C3—C8	121.64 (10)	C9—C10—H12	109.5
N1—C5—O1	120.24 (10)	H11—C10—H12	109.5
N1—C5—C4	124.07 (10)	C9—C10—H13	109.5
O1—C5—C4	115.69 (9)	H11—C10—H13	109.5
N3—C6—C2	179.73 (12)	H12—C10—H13	109.5
N4—C7—C4	175.40 (11)
C5—N1—C1—N2	−179.18 (9)	C1—C2—C3—C8	179.22 (10)
C5—N1—C1—C2	0.63 (15)	C6—C2—C3—C8	−0.09 (16)
C3—C2—C1—N2	179.63 (10)	C1—N1—C5—O1	−179.82 (9)
C6—C2—C1—N2	−1.06 (16)	C1—N1—C5—C4	−0.20 (16)
C3—C2—C1—N1	−0.16 (16)	C9—O1—C5—N1	2.04 (14)
C6—C2—C1—N1	179.15 (9)	C9—O1—C5—C4	−177.61 (9)
C5—C4—C3—C2	1.12 (15)	C3—C4—C5—N1	−0.69 (16)
C7—C4—C3—C2	−179.37 (10)	C7—C4—C5—N1	179.80 (10)
C5—C4—C3—C8	−178.83 (10)	C3—C4—C5—O1	178.95 (9)
C7—C4—C3—C8	0.68 (16)	C7—C4—C5—O1	−0.56 (15)
C1—C2—C3—C4	−0.73 (16)	C5—O1—C9—C10	−170.90 (9)
C6—C2—C3—C4	179.96 (9)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···N3^i	0.883 (15)	2.230 (15)	3.1040 (17)	170.1 (13)
N2—H1···N4^ii	0.865 (16)	2.308 (16)	3.1676 (17)	172.8 (13)

Symmetry codes: (i) −x+2, −y+2, −z+1; (ii) x+1, y−1, z.