Crystal structure of 3-bromo-4-di­methyl­amino-1-methyl-1,2,4-triazol-5(4H)-one

The title compound, C₅H₉BrN₄O, was obtained as a minor by-product in the synthesis of 4-di­methyl­amino-1-methyl-1,2,4-triazolin-5-one. Except for the methyl groups of the 4-dimethylamino moiety, all the non-H atoms lie on a crystallographic mirror plane." In the crystal, the mol­ecules are linked by C—Br...O=C inter­actions [Br...O = 2.877 (2) Å, C—Br...O = 174.6 (1)°] into infinite chains in the c-axis direction.

Key indicators

• Single-crystal X-ray study
• T = 233 K
• Mean [sigma](N-C) = 0.005 Å
• R factor = 0.028
• wR factor = 0.065
• Data-to-parameter ratio = 10.7

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT431_ALERT_2_B Short Inter HL..A  Contact Br1    ..  O1      ..       2.88 Ang.

Alert level C
PLAT019_ALERT_1_C  _diffrn_measured_fraction_theta_full/_max < 1.0      0.984 Report

Alert level G
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          4 Note
PLAT164_ALERT_4_G Nr. of Refined C-H H-Atoms in Heavy-Atom Struct.          3 Note
PLAT172_ALERT_4_G The CIF-Embedded .res File Contains DFIX Records          2 Report
PLAT860_ALERT_3_G Number of Least-Squares Restraints .............          6 Note
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          79 %

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   1 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

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

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S1. Comment

Triazolinones are of relevance due to their wide range of pesticidal activities. The molecular structure of 3-bromo-4-(dimethylamino)-1-methyl-1,2,4-triazolin-5-one is shown in Figure 1. The triazole rings are located in the crystallographic mirror plane (Figure 2), whereas the C4 methyl groups are situated out of this plane. The molecules are linked by short intermolecular C—Br···O=C contacts into infinite chains in the direction of the c axis (Figure 3). The Br···O distance of 2.877 (2) Å is significantly shorter than the sum of van der Waals radii. Theoretical calculations predicted negative ring and positive end cap domains of halogen atoms due to their polarizability (Awwadi et al., 2006). The almost linear C—Br···O angle of 174.6 (1)° indicates an interaction involving the positive end cap of the Br atom. Thus, the Br atom acts as an electron-acceptor (X-bond donor) in this case.

Related literature

For synthesis of related 4-amino-1-methyl-1,2,4-triazolin-5-ones, see: Kröger et al. (1965). For related structures with Br···O═C interactions, see: 5-bromopyrimidin-2-one (Yathirajan et al., 2007); 3,5-dibromopyran-2-one (Reus et al., 2012); N-bromosaccharin (Dolenc & Modec, 2009); N-bromosuccinimide (Jabay et al., 1977); dibromantin (Kruszynski, 2007). For the theory of halogen interactions, see: Awwadi et al. (2006). For details of the synthesis, see: Schwärzler et al. (2009).

S2. Experimental

The title compound was obtained as a minor by-product in the synthesis of 4-(dimethylamino)-1-methyl-1,2,4-triazolin-5-one by hydrolysis of 5-bromo-4-(dimethylamino)-1-methyl-1,2,4-triazolium hexafluorophosphate (Schwärzler et al., 2009) in MeOH/H₂O. It is assumed that the 5-bromo compound was contaminated with a trace of the corresponding 3,5-dibromo compound which resulted in the formation of the present 3-bromo-1,2,4-triazolin-5-one.

S3. Refinement

The H atoms were identified in a difference map and those of the C4 methyl group were idealized and included as rigid groups, allowed to rotate but not tip (C—H = 0.97 Å). The C3 methyl group was found to be disordered over two orientations related by mirror symmetry. Its H positions were refined with restrained C—H and H···H distances of 0.97 (1) Å and 1.58 (2) Å, respectively. The U_iso parameters of all H atoms were set to 1.5 U_eq(C) of the parent carbon atom.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006) and ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms. One component of the disordered C3 methyl group has been omitted for clarity. Symmetry code (i): x, -y, z.
	Fig. 2. Arrangement of the triazole rings parallel to the ac plane. One component of the disordered C3 methyl group has been omitted for clarity.
	Fig. 3. Infinite chains of molecules linked by Br···O interactions. One component of the disordered C3 methyl group has been omitted for clarity. Symmetry code (ii): x, y, 1 + z; (iii): x, y, -1 + z.

3-Bromo-4-dimethylamino-1-methyl-1,2,4-triazol-5(4H)-one

Crystal data

C5H9BrN4O	F(000) = 440
Mr = 221.07	Dx = 1.772 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
a = 15.1993 (6) Å	Cell parameters from 3066 reflections
b = 6.9377 (4) Å	θ = 1.0–25.0°
c = 7.8771 (7) Å	µ = 4.91 mm^−1
β = 93.869 (3)°	T = 233 K
V = 828.73 (9) Å^3	Prism, colorless
Z = 4	0.09 × 0.08 × 0.07 mm

Data collection

Nonius KappaCCD diffractometer	734 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.034
Graphite monochromator	θmax = 25.1°, θmin = 2.6°
phi and ω scans	h = −13→18
2310 measured reflections	k = −8→8
806 independent reflections	l = −9→8

Refinement

Refinement on F^2	6 restraints
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.065	w = 1/[σ^2(Fo^2) + (0.033P)^2 + 0.5344P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
806 reflections	Δρmax = 0.50 e Å^−3
75 parameters	Δρmin = −0.44 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Br1	0.22218 (3)	0.0000	0.18788 (4)	0.03459 (19)
O1	0.17449 (19)	0.0000	−0.4649 (3)	0.0426 (8)
N1	0.3186 (2)	0.0000	−0.1029 (4)	0.0319 (8)
N2	0.2997 (2)	0.0000	−0.2784 (4)	0.0302 (8)
N3	0.1742 (2)	0.0000	−0.1669 (4)	0.0282 (7)
N4	0.0841 (2)	0.0000	−0.1382 (4)	0.0329 (8)
C1	0.2418 (3)	0.0000	−0.0415 (4)	0.0269 (9)
C2	0.2125 (3)	0.0000	−0.3221 (4)	0.0322 (10)
C3	0.3694 (3)	0.0000	−0.3938 (6)	0.0445 (11)
H3A	0.352 (3)	−0.069 (5)	−0.497 (4)	0.067*	0.5
H3B	0.4248 (19)	−0.047 (6)	−0.343 (6)	0.067*	0.5
H3C	0.375 (3)	0.136 (2)	−0.420 (6)	0.067*	0.5
C4	0.04175 (19)	0.1766 (5)	−0.2044 (4)	0.0478 (8)
H4A	0.0726	0.2877	−0.1550	0.072*
H4B	−0.0192	0.1791	−0.1750	0.072*
H4C	0.0438	0.1801	−0.3272	0.072*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0454 (3)	0.0368 (3)	0.0211 (3)	0.000	−0.00047 (17)	0.000
O1	0.0429 (17)	0.067 (2)	0.0181 (14)	0.000	0.0024 (12)	0.000
N1	0.037 (2)	0.0330 (19)	0.0255 (17)	0.000	−0.0004 (14)	0.000
N2	0.0279 (19)	0.0367 (19)	0.0261 (17)	0.000	0.0020 (13)	0.000
N3	0.0257 (17)	0.0392 (19)	0.0197 (16)	0.000	0.0019 (12)	0.000
N4	0.0290 (18)	0.044 (2)	0.0252 (17)	0.000	0.0013 (13)	0.000
C1	0.035 (2)	0.027 (2)	0.019 (2)	0.000	−0.0026 (16)	0.000
C2	0.040 (3)	0.032 (2)	0.025 (2)	0.000	0.0051 (18)	0.000
C3	0.036 (3)	0.063 (3)	0.036 (2)	0.000	0.0124 (19)	0.000
C4	0.0402 (19)	0.059 (2)	0.0445 (18)	0.0125 (15)	0.0051 (14)	0.0066 (17)

Geometric parameters (Å, º)

Br1—C1	1.851 (4)	N4—C4	1.464 (4)
O1—C2	1.230 (4)	N4—C4^i	1.464 (4)
N1—C1	1.292 (5)	C3—H3A	0.967 (10)
N1—N2	1.392 (5)	C3—H3B	0.965 (10)
N2—C2	1.346 (5)	C3—H3C	0.969 (10)
N2—C3	1.442 (5)	C4—H4A	0.9700
N3—C1	1.377 (4)	C4—H4B	0.9700
N3—C2	1.389 (5)	C4—H4C	0.9700
N3—N4	1.403 (4)
Br1···O1^ii	2.876 (3)
C1—N1—N2	103.9 (3)	O1—C2—N3	127.3 (4)
C2—N2—N1	112.8 (3)	N2—C2—N3	103.8 (3)
C2—N2—C3	126.2 (3)	N2—C3—H3A	111 (4)
N1—N2—C3	121.0 (3)	N2—C3—H3B	113 (3)
C1—N3—C2	107.1 (3)	H3A—C3—H3B	111 (2)
C1—N3—N4	125.0 (3)	N2—C3—H3C	102 (4)
C2—N3—N4	127.9 (3)	H3A—C3—H3C	109 (2)
N3—N4—C4	110.6 (2)	H3B—C3—H3C	110 (2)
N3—N4—C4^i	110.6 (2)	N4—C4—H4A	109.5
C4—N4—C4^i	113.7 (3)	N4—C4—H4B	109.5
N1—C1—N3	112.4 (3)	H4A—C4—H4B	109.5
N1—C1—Br1	125.0 (3)	N4—C4—H4C	109.5
N3—C1—Br1	122.6 (3)	H4A—C4—H4C	109.5
O1—C2—N2	128.9 (4)	H4B—C4—H4C	109.5

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