A second monoclinic polymorph of 2-amino-4,6-dichloro-pyrimidine.

The title chloro-substituted 2-amino-pyrimidine, C(4)H(3)Cl(2)N(3), is a second monoclinic polymorph of this compound which crystallizes in the space group C2/c. The structure was previously reported [Clews & Cochran (1948 ▶). Acta Cryst. 1, 4-11] in the space group P21/a. There are two crystallographically independent mol-ecules in the asymmetric unit and each mol-ecule is planar. The dihedral angle between the two pyrimidine rings is 30.71 (12)°. In the crystal structure, mol-ecules are linked via N-H⋯N inter-molecular hydrogen bonds, forming infinite one-dimensional chains along the a axis. These hydrogen bonds generate R(2) (2)(8) ring motifs. The chains are stacked along the b axis.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For details of hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For related structures, see: the polymorph reported by Clews & Cochran (1948 ▶); Low et al. (2002 ▶). For applications of pyrimidine compounds and their supra­molecular chemistry, see, for example: Blackburn & Gait (1996 ▶); Brown (1988 ▶); Hurst (1980 ▶); Goswami et al. (2008a ▶,b ▶); Ligthart et al. (2005 ▶); Sherrington & Taskinen (2001 ▶).

Experimental

Crystal data

C4H3Cl2N3

M = 163.99

Monoclinic,

a = 32.060 (4) Å

b = 3.8045 (6) Å

c = 21.302 (3) Å

β = 102.193 (7)°

V = 2539.6 (6) Å3

Z = 16

Mo Kα radiation

μ = 0.92 mm−1

T = 296 (2) K

0.57 × 0.14 × 0.02 mm

Data collection

Bruker SMART APEX2 CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T min = 0.620, T max = 0.985

12772 measured reflections

2886 independent reflections

1875 reflections with I > 2σ(I)

R int = 0.051

Refinement

R[F 2 > 2σ(F 2)] = 0.040

wR(F 2) = 0.098

S = 1.02

2886 reflections

187 parameters

All H-atom parameters refined

Δρmax = 0.22 e Å−3

Δρmin = −0.24 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808023714/sj2524sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808023714/sj2524Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C4H3Cl2N3	F000 = 1312
Mr = 163.99	Dx = 1.716 Mg m−3
Monoclinic, C2/c	Melting point = 492–494 K
Hall symbol: -C 2yc	Mo Kα radiation λ = 0.71073 Å
a = 32.060 (4) Å	Cell parameters from 2886 reflections
b = 3.8045 (6) Å	θ = 1.3–27.5º
c = 21.302 (3) Å	µ = 0.92 mm−1
β = 102.193 (7)º	T = 296 (2) K
V = 2539.6 (6) Å3	Block, colorless
Z = 16	0.57 × 0.14 × 0.02 mm

Bruker SMART APEX2 CCD area-detector diffractometer	2886 independent reflections
Radiation source: fine-focus sealed tube	1875 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.051
Detector resolution: 8.33 pixels mm-1	θmax = 27.5º
T = 296(2) K	θmin = 1.3º
ω scans	h = −40→40
Absorption correction: multi-scan(SADABS; Bruker, 2005)	k = −4→4
Tmin = 0.620, Tmax = 0.985	l = −27→27
12772 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.040	All H-atom parameters refined
wR(F2) = 0.098	w = 1/[σ2(Fo2) + (0.0403P)2] where P = (Fo2 + 2Fc2)/3
S = 1.02	(Δ/σ)max = 0.001
2886 reflections	Δρmax = 0.22 e Å−3
187 parameters	Δρmin = −0.24 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

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.

	x	y	z	Uiso*/Ueq
Cl1A	0.330814 (19)	0.45738 (18)	0.35093 (3)	0.0475 (2)
Cl2A	0.49584 (2)	0.5271 (2)	0.33992 (4)	0.0572 (2)
N1A	0.46421 (6)	0.7708 (5)	0.43348 (9)	0.0371 (5)
N2A	0.38986 (6)	0.7401 (5)	0.43849 (9)	0.0349 (5)
N3A	0.43941 (8)	0.9927 (7)	0.51907 (11)	0.0490 (6)
H2NA	0.4619 (8)	1.056 (7)	0.5293 (12)	0.033 (8)*
H1NA	0.4174 (9)	1.026 (7)	0.5366 (14)	0.057 (9)*
C1A	0.38306 (7)	0.5786 (6)	0.38271 (11)	0.0338 (6)
C2A	0.41389 (8)	0.5008 (7)	0.34867 (12)	0.0377 (6)
H2A	0.4102 (7)	0.386 (6)	0.3120 (11)	0.034 (7)*
C3A	0.45423 (7)	0.6088 (7)	0.37766 (11)	0.0353 (6)
C4A	0.43110 (7)	0.8296 (7)	0.46279 (11)	0.0350 (6)
Cl1B	0.58263 (2)	1.02542 (19)	0.31034 (3)	0.0510 (2)
Cl2B	0.73894 (2)	0.50031 (18)	0.32094 (3)	0.0474 (2)
N1B	0.71199 (6)	0.7404 (6)	0.41918 (9)	0.0389 (5)
N2B	0.64127 (6)	0.9690 (6)	0.41463 (9)	0.0406 (5)
N3B	0.69119 (9)	0.9534 (8)	0.50908 (11)	0.0589 (7)
H1NB	0.6706 (10)	1.049 (8)	0.5237 (16)	0.080 (12)*
H2NB	0.7156 (10)	0.881 (9)	0.5264 (16)	0.075 (11)*
C1B	0.63348 (7)	0.9103 (6)	0.35235 (12)	0.0364 (6)
C2B	0.66172 (7)	0.7709 (7)	0.31888 (11)	0.0374 (6)
H2B	0.6550 (7)	0.753 (7)	0.2743 (12)	0.047 (7)*
C3B	0.70066 (7)	0.6887 (7)	0.35702 (11)	0.0361 (6)
C4B	0.68134 (8)	0.8851 (7)	0.44634 (11)	0.0403 (6)

	U11	U22	U33	U12	U13	U23
Cl1A	0.0320 (3)	0.0586 (5)	0.0491 (4)	−0.0065 (3)	0.0027 (3)	−0.0029 (3)
Cl2A	0.0442 (4)	0.0698 (5)	0.0658 (5)	−0.0003 (4)	0.0298 (3)	−0.0132 (4)
N1A	0.0293 (10)	0.0422 (13)	0.0402 (11)	0.0003 (10)	0.0086 (9)	−0.0014 (11)
N2A	0.0295 (10)	0.0416 (13)	0.0339 (10)	0.0028 (10)	0.0073 (8)	−0.0013 (10)
N3A	0.0351 (14)	0.0707 (19)	0.0418 (13)	−0.0073 (14)	0.0093 (11)	−0.0161 (13)
C1A	0.0293 (12)	0.0320 (14)	0.0385 (13)	−0.0009 (11)	0.0040 (10)	0.0039 (11)
C2A	0.0378 (14)	0.0402 (16)	0.0355 (13)	−0.0012 (13)	0.0087 (11)	−0.0057 (13)
C3A	0.0338 (13)	0.0354 (14)	0.0396 (13)	0.0033 (12)	0.0141 (10)	0.0001 (12)
C4A	0.0327 (13)	0.0404 (15)	0.0315 (12)	−0.0020 (12)	0.0060 (10)	0.0013 (12)
Cl1B	0.0344 (4)	0.0669 (5)	0.0514 (4)	0.0072 (4)	0.0083 (3)	0.0056 (4)
Cl2B	0.0358 (3)	0.0566 (4)	0.0546 (4)	−0.0001 (3)	0.0204 (3)	−0.0103 (3)
N1B	0.0355 (11)	0.0438 (13)	0.0386 (11)	0.0036 (11)	0.0109 (9)	0.0016 (10)
N2B	0.0388 (12)	0.0481 (14)	0.0377 (11)	0.0044 (11)	0.0143 (9)	0.0001 (11)
N3B	0.0534 (17)	0.087 (2)	0.0368 (13)	0.0187 (16)	0.0102 (12)	−0.0034 (13)
C1B	0.0315 (13)	0.0386 (15)	0.0407 (13)	0.0001 (12)	0.0112 (10)	0.0014 (12)
C2B	0.0352 (14)	0.0465 (17)	0.0328 (13)	−0.0025 (13)	0.0123 (11)	−0.0036 (13)
C3B	0.0329 (13)	0.0369 (15)	0.0416 (14)	−0.0031 (12)	0.0151 (11)	−0.0009 (12)
C4B	0.0398 (15)	0.0477 (16)	0.0352 (13)	0.0043 (13)	0.0122 (11)	0.0023 (12)

Cl1A—C1A	1.731 (2)	Cl1B—C1B	1.742 (2)
Cl2A—C3A	1.725 (2)	Cl2B—C3B	1.735 (2)
N1A—C3A	1.317 (3)	N1B—C3B	1.312 (3)
N1A—C4A	1.359 (3)	N1B—C4B	1.358 (3)
N2A—C1A	1.314 (3)	N2B—C1B	1.316 (3)
N2A—C4A	1.357 (3)	N2B—C4B	1.357 (3)
N3A—C4A	1.326 (3)	N3B—C4B	1.332 (3)
N3A—H2NA	0.75 (2)	N3B—H1NB	0.87 (3)
N3A—H1NA	0.87 (3)	N3B—H2NB	0.84 (3)
C1A—C2A	1.376 (3)	C1B—C2B	1.372 (3)
C2A—C3A	1.373 (3)	C2B—C3B	1.374 (3)
C2A—H2A	0.88 (2)	C2B—H2B	0.93 (2)
C3A—N1A—C4A	115.3 (2)	C3B—N1B—C4B	114.8 (2)
C1A—N2A—C4A	115.11 (19)	C1B—N2B—C4B	114.9 (2)
C4A—N3A—H2NA	114 (2)	C4B—N3B—H1NB	114 (2)
C4A—N3A—H1NA	115.4 (19)	C4B—N3B—H2NB	112 (2)
H2NA—N3A—H1NA	130 (3)	H1NB—N3B—H2NB	134 (3)
N2A—C1A—C2A	125.2 (2)	N2B—C1B—C2B	125.7 (2)
N2A—C1A—Cl1A	116.12 (18)	N2B—C1B—Cl1B	115.67 (18)
C2A—C1A—Cl1A	118.68 (19)	C2B—C1B—Cl1B	118.62 (19)
C3A—C2A—C1A	114.3 (2)	C1B—C2B—C3B	113.4 (2)
C3A—C2A—H2A	118.9 (14)	C1B—C2B—H2B	121.6 (15)
C1A—C2A—H2A	126.7 (15)	C3B—C2B—H2B	124.8 (14)
N1A—C3A—C2A	124.9 (2)	N1B—C3B—C2B	125.9 (2)
N1A—C3A—Cl2A	116.14 (18)	N1B—C3B—Cl2B	115.99 (17)
C2A—C3A—Cl2A	118.95 (19)	C2B—C3B—Cl2B	118.12 (18)
N3A—C4A—N2A	117.1 (2)	N3B—C4B—N2B	116.9 (2)
N3A—C4A—N1A	117.7 (2)	N3B—C4B—N1B	117.8 (2)
N2A—C4A—N1A	125.2 (2)	N2B—C4B—N1B	125.3 (2)

D—H···A	D—H	H···A	D···A	D—H···A
N3A—H2NA···N1Ai	0.75 (3)	2.43 (3)	3.172 (3)	176 (2)
N3A—H1NA···N2Bi	0.87 (3)	2.33 (3)	3.201 (3)	172 (2)
N3B—H1NB···N2Ai	0.87 (3)	2.39 (3)	3.253 (4)	174 (3)
N3B—H2NB···N1Bii	0.84 (3)	2.41 (3)	3.242 (3)	172 (3)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3A—H2NA⋯N1Ai	0.75 (3)	2.43 (3)	3.172 (3)	176 (2)
N3A—H1NA⋯N2Bi	0.87 (3)	2.33 (3)	3.201 (3)	172 (2)
N3B—H1NB⋯N2Ai	0.87 (3)	2.39 (3)	3.253 (4)	174 (3)
N3B—H2NB⋯N1Bii	0.84 (3)	2.41 (3)	3.242 (3)	172 (3)

Symmetry codes: (i) ; (ii) .