Irreversible single-crystal to polycrystal and ­reversible single-crystal to single-crystal phase transformations in cyanurates

4,6-Dimethoxy-3-methyldihydrotriazine-2-one (1) undergoes a single-crystal to single-crystal reversible phase transformation at 319 K. The low-temperature phase crystallizes in monoclinic space group P2₁/n with two crystallographically independent molecules in the asymmetric unit. The high-temperature phase is obtained by heating a single crystal of the low-temperature phase. This phase is orthorhombic, space group Pnma, with the molecules occupying a crystallographic mirror plane. The enthalpy of the transformation is 1.34 kJ mol^-1. The small energy difference between the two phases and the minimal atomic movement facilitate the single-crystal to single-crystal reversible phase transformation with no destruction of the crystal lattice. On further heating, the high-temperature phase undergoes methyl rearrangement in the solid state. 2,4,6-Trimethoxy-1,3,5-triazine (3), on the other hand, undergoes an irreversible phase transformation from single-crystal to polycrystalline material at 340 K with an enthalpy of 3.9 kJ mol^-1; upon further heating it melts and methyl rearrangement takes place.

Computing details

Data collection: KappaCCD (Nonius,2000) for LTP, HTP; SMART V.4.209 (Siemens, 1995) for HTP(359K). Cell refinement: DENZO SMN (Otwinowski & Minor,1997) for LTP, HTP; SAINT V.4.209 (Siemens, 1995) for HTP(359K). Data reduction: DENZO SMN (Otwinowski & Minor,1997) for LTP, HTP; SAINT V.4.209 (Siemens, 1995) for HTP(359K). Program(s) used to solve structure: SHELXS97 (Sheldrick, 1990) for LTP, HTP; SHELXS97 (Sheldrick, 1997) for HTP(359K). For all compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 1997). Molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) for LTP, HTP; ORTEP-3 (Farrugia, 1997) for HTP(359K).

Figures

(LTP) 4,6-Dimethoxy-3-methyl-dihydro-triazine-2-one

Crystal data

C6H9N3O3	F(000) = 720
Mr = 171.16	Dx = 1.412 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71070 Å
a = 13.480 (2) Å	Cell parameters from 3758 reflections
b = 14.172 (2) Å	θ = 1.0–28.2°
c = 8.433 (1) Å	µ = 0.12 mm^−1
β = 92.07 (2)°	T = 298 K
V = 1610.0 (2) Å^3	Prism, colorless
Z = 8	0.35 × 0.3 × 0.3 mm

Data collection

Nonius KappaCCD diffractometer	2273 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.046
Graphite monochromator	θmax = 28.3°, θmin = 2.1°
phi–scan	h = −17→17
3758 measured reflections	k = −18→0
3758 independent reflections	l = 0→10

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.056	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.180	w = 1/[σ^2(Fo^2) + (0.0773P)^2 + 0.7666P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.158
3758 reflections	Δρmax = 0.22 e Å^−3
224 parameters	Δρmin = −0.18 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.046 (7)

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
O11	0.11930 (16)	−0.09655 (14)	0.7723 (2)	0.0723 (6)
O12	0.12214 (13)	−0.03273 (13)	0.24944 (19)	0.0576 (5)
O13	0.15749 (13)	0.20508 (12)	0.6010 (2)	0.0542 (5)
N11	0.13655 (14)	0.05751 (13)	0.7000 (2)	0.0441 (5)
N12	0.11726 (13)	−0.06465 (13)	0.5092 (2)	0.0420 (5)
N13	0.14134 (14)	0.09077 (14)	0.4230 (2)	0.0439 (5)
C11	0.12442 (17)	−0.03665 (17)	0.6687 (3)	0.0446 (5)
C12	0.12741 (14)	0.00114 (17)	0.3955 (2)	0.0407 (5)
C13	0.14419 (15)	0.11299 (16)	0.5788 (3)	0.0389 (5)
C14	0.1049 (2)	−0.16529 (17)	0.4719 (4)	0.0593 (7)
H14A	0.0650	−0.1720	0.3759	0.089*
H14B	0.0727	−0.1962	0.5573	0.089*
H14C	0.1688	−0.1934	0.4581	0.089*
C15	0.1289 (2)	0.0353 (2)	0.1206 (3)	0.0720 (9)
H15A	0.0754	0.0797	0.1255	0.108*
H15B	0.1248	0.0027	0.0207	0.108*
H15C	0.1911	0.0681	0.1306	0.108*
C16	0.1601 (2)	0.2405 (2)	0.7618 (3)	0.0701 (8)
H16A	0.0962	0.2321	0.8064	0.105*
H16B	0.1767	0.3063	0.7615	0.105*
H16C	0.2092	0.2065	0.8242	0.105*
O21	0.09978 (19)	0.65764 (14)	1.2798 (2)	0.0806 (7)
O22	0.11168 (12)	0.59344 (13)	0.75859 (18)	0.0521 (5)
O23	0.14528 (13)	0.35632 (11)	1.1130 (2)	0.0534 (5)
N21	0.12268 (14)	0.50404 (13)	1.2092 (2)	0.0440 (5)
N22	0.10644 (13)	0.62603 (13)	1.0175 (2)	0.0406 (5)
N23	0.12913 (13)	0.46987 (13)	0.9328 (2)	0.0407 (5)
C21	0.10944 (18)	0.59785 (17)	1.1775 (3)	0.0459 (6)
C22	0.11627 (14)	0.55969 (16)	0.9045 (2)	0.0375 (5)
C23	0.13180 (15)	0.44823 (15)	1.0888 (3)	0.0376 (5)
C24	0.0944 (2)	0.72659 (17)	0.9794 (3)	0.0563 (7)
H24A	0.1569	0.7521	0.9490	0.084*
H24B	0.0721	0.7597	1.0708	0.084*
H24C	0.0464	0.7337	0.8934	0.084*
C25	0.1210 (2)	0.5256 (2)	0.6301 (3)	0.0648 (8)
H25A	0.1838	0.4940	0.6414	0.097*
H25B	0.1168	0.5580	0.5301	0.097*
H25C	0.0684	0.4800	0.6343	0.097*
C26	0.1506 (2)	0.3232 (2)	1.2754 (3)	0.0665 (8)
H26A	0.2017	0.3569	1.3338	0.100*
H26B	0.1655	0.2569	1.2770	0.100*
H26C	0.0880	0.3337	1.3232	0.100*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O11	0.1178 (17)	0.0489 (12)	0.0504 (12)	−0.0053 (11)	0.0054 (10)	0.0144 (10)
O12	0.0698 (11)	0.0662 (13)	0.0369 (9)	−0.0008 (9)	0.0015 (7)	−0.0144 (8)
O13	0.0736 (11)	0.0344 (10)	0.0546 (11)	−0.0034 (8)	0.0033 (8)	−0.0070 (8)
N11	0.0577 (11)	0.0414 (11)	0.0333 (10)	0.0003 (9)	0.0028 (8)	−0.0024 (8)
N12	0.0475 (10)	0.0352 (11)	0.0432 (11)	−0.0018 (8)	0.0012 (8)	−0.0065 (8)
N13	0.0552 (11)	0.0402 (12)	0.0363 (10)	0.0005 (8)	0.0023 (8)	−0.0008 (8)
C11	0.0544 (13)	0.0402 (14)	0.0392 (13)	−0.0002 (10)	0.0022 (9)	0.0034 (10)
C12	0.0392 (11)	0.0480 (14)	0.0347 (12)	0.0018 (9)	0.0004 (8)	−0.0068 (10)
C13	0.0413 (11)	0.0354 (13)	0.0398 (12)	0.0014 (9)	0.0019 (8)	−0.0029 (10)
C14	0.0654 (16)	0.0384 (15)	0.0739 (19)	−0.0042 (11)	0.0021 (13)	−0.0123 (13)
C15	0.090 (2)	0.093 (2)	0.0334 (14)	0.0019 (17)	0.0034 (12)	−0.0005 (14)
C16	0.091 (2)	0.0542 (18)	0.0657 (19)	−0.0028 (14)	0.0043 (14)	−0.0282 (15)
O21	0.150 (2)	0.0465 (11)	0.0453 (11)	0.0054 (12)	0.0063 (11)	−0.0125 (9)
O22	0.0644 (10)	0.0589 (11)	0.0328 (9)	−0.0021 (8)	0.0005 (7)	0.0116 (8)
O23	0.0754 (11)	0.0334 (10)	0.0512 (10)	0.0030 (8)	0.0006 (8)	0.0064 (8)
N21	0.0606 (12)	0.0376 (11)	0.0337 (10)	−0.0008 (9)	0.0011 (8)	0.0032 (8)
N22	0.0510 (10)	0.0324 (10)	0.0385 (10)	−0.0021 (8)	0.0020 (7)	0.0046 (8)
N23	0.0517 (11)	0.0378 (11)	0.0326 (10)	0.0000 (8)	0.0002 (7)	−0.0009 (8)
C21	0.0670 (15)	0.0376 (13)	0.0332 (12)	−0.0020 (11)	0.0017 (10)	0.0008 (10)
C22	0.0380 (11)	0.0441 (13)	0.0302 (11)	−0.0040 (9)	0.0007 (8)	0.0065 (9)
C23	0.0404 (11)	0.0347 (12)	0.0377 (12)	−0.0008 (8)	0.0002 (8)	0.0036 (9)
C24	0.0737 (16)	0.0330 (13)	0.0624 (17)	0.0023 (11)	0.0042 (12)	0.0101 (12)
C25	0.0781 (18)	0.088 (2)	0.0285 (13)	−0.0035 (15)	−0.0003 (11)	0.0008 (13)
C26	0.092 (2)	0.0480 (16)	0.0585 (17)	0.0026 (14)	−0.0034 (14)	0.0225 (13)

Geometric parameters (Å, º)

O11—C11	1.221 (3)	O21—C21	1.220 (3)
O12—C12	1.321 (3)	O22—C22	1.319 (2)
O12—C15	1.458 (3)	O22—C25	1.457 (3)
O13—C13	1.330 (3)	O23—C23	1.330 (3)
O13—C16	1.445 (3)	O23—C26	1.447 (3)
N11—C13	1.297 (3)	N21—C23	1.297 (3)
N11—C11	1.369 (3)	N21—C21	1.367 (3)
N12—C12	1.348 (3)	N22—C22	1.349 (3)
N12—C11	1.402 (3)	N22—C21	1.406 (3)
N12—C14	1.469 (3)	N22—C24	1.469 (3)
N13—C12	1.304 (3)	N23—C22	1.306 (3)
N13—C13	1.350 (3)	N23—C23	1.350 (3)
C14—H14A	0.9600	C24—H24A	0.9600
C14—H14B	0.9600	C24—H24B	0.9600
C14—H14C	0.9600	C24—H24C	0.9600
C15—H15A	0.9600	C25—H25A	0.9600
C15—H15B	0.9600	C25—H25B	0.9600
C15—H15C	0.9600	C25—H25C	0.9600
C16—H16A	0.9600	C26—H26A	0.9600
C16—H16B	0.9600	C26—H26B	0.9600
C16—H16C	0.9600	C26—H26C	0.9600
C12—O12—C15	116.9 (2)	C22—O22—C25	116.8 (2)
C13—O13—C16	118.1 (2)	C23—O23—C26	117.7 (2)
C13—N11—C11	116.83 (19)	C23—N21—C21	117.08 (19)
C12—N12—C11	118.79 (19)	C22—N22—C21	118.69 (19)
C12—N12—C14	122.2 (2)	C22—N22—C24	122.30 (19)
C11—N12—C14	118.9 (2)	C21—N22—C24	119.0 (2)
C12—N13—C13	113.55 (19)	C22—N23—C23	113.50 (18)
O11—C11—N11	123.3 (2)	O21—C21—N21	123.6 (2)
O11—C11—N12	119.0 (2)	O21—C21—N22	118.8 (2)
N11—C11—N12	117.7 (2)	N21—C21—N22	117.6 (2)
N13—C12—O12	121.5 (2)	N23—C22—O22	121.7 (2)
N13—C12—N12	124.4 (2)	N23—C22—N22	124.45 (19)
O12—C12—N12	114.1 (2)	O22—C22—N22	113.8 (2)
N11—C13—O13	119.9 (2)	N21—C23—O23	119.6 (2)
N11—C13—N13	128.7 (2)	N21—C23—N23	128.7 (2)
O13—C13—N13	111.4 (2)	O23—C23—N23	111.76 (19)
N12—C14—H14A	109.5	N22—C24—H24A	109.5
N12—C14—H14B	109.5	N22—C24—H24B	109.5
H14A—C14—H14B	109.5	H24A—C24—H24B	109.5
N12—C14—H14C	109.5	N22—C24—H24C	109.5
H14A—C14—H14C	109.5	H24A—C24—H24C	109.5
H14B—C14—H14C	109.5	H24B—C24—H24C	109.5
O12—C15—H15A	109.5	O22—C25—H25A	109.5
O12—C15—H15B	109.5	O22—C25—H25B	109.5
H15A—C15—H15B	109.5	H25A—C25—H25B	109.5
O12—C15—H15C	109.5	O22—C25—H25C	109.5
H15A—C15—H15C	109.5	H25A—C25—H25C	109.5
H15B—C15—H15C	109.5	H25B—C25—H25C	109.5
O13—C16—H16A	109.5	O23—C26—H26A	109.5
O13—C16—H16B	109.5	O23—C26—H26B	109.5
H16A—C16—H16B	109.5	H26A—C26—H26B	109.5
O13—C16—H16C	109.5	O23—C26—H26C	109.5
H16A—C16—H16C	109.5	H26A—C26—H26C	109.5
H16B—C16—H16C	109.5	H26B—C26—H26C	109.5
C13—N11—C11—O11	177.7 (2)	C23—N21—C21—O21	179.9 (2)
C13—N11—C11—N12	−2.5 (3)	C23—N21—C21—N22	0.2 (3)
C12—N12—C11—O11	−177.1 (2)	C22—N22—C21—O21	−179.4 (2)
C14—N12—C11—O11	−0.6 (3)	C24—N22—C21—O21	1.6 (3)
C12—N12—C11—N11	3.2 (3)	C22—N22—C21—N21	0.3 (3)
C14—N12—C11—N11	179.6 (2)	C24—N22—C21—N21	−178.7 (2)
C13—N13—C12—O12	179.63 (18)	C23—N23—C22—O22	−179.90 (17)
C13—N13—C12—N12	−0.4 (3)	C23—N23—C22—N22	0.0 (3)
C15—O12—C12—N13	−2.2 (3)	C25—O22—C22—N23	0.4 (3)
C15—O12—C12—N12	177.8 (2)	C25—O22—C22—N22	−179.53 (19)
C11—N12—C12—N13	−1.7 (3)	C21—N22—C22—N23	−0.4 (3)
C14—N12—C12—N13	−178.0 (2)	C24—N22—C22—N23	178.5 (2)
C11—N12—C12—O12	178.26 (18)	C21—N22—C22—O22	179.53 (18)
C14—N12—C12—O12	1.9 (3)	C24—N22—C22—O22	−1.5 (3)
C11—N11—C13—O13	−179.06 (19)	C21—N21—C23—O23	179.70 (19)
C11—N11—C13—N13	0.4 (3)	C21—N21—C23—N23	−0.7 (3)
C16—O13—C13—N11	−1.7 (3)	C26—O23—C23—N21	−0.9 (3)
C16—O13—C13—N13	178.72 (19)	C26—O23—C23—N23	179.4 (2)
C12—N13—C13—N11	1.2 (3)	C22—N23—C23—N21	0.6 (3)
C12—N13—C13—O13	−179.36 (18)	C22—N23—C23—O23	−179.80 (18)

(HTP) 4,6-Dimethoxy-3-methyl-dihydro-triazine-2-one

Crystal data

C6H9N3O3	Dx = 1.393 Mg m^−3
Mr = 171.16	Mo Kα radiation, λ = 0.71070 Å
Orthorhombic, Pnma	Cell parameters from 2809 reflections
a = 8.465 (1) Å	θ = 1.0–25.9°
b = 6.749 (1) Å	µ = 0.11 mm^−1
c = 14.284 (2) Å	T = 320 K
V = 816.0 (2) Å^3	Prism, colorless
Z = 4	0.35 × 0.3 × 0.3 mm
F(000) = 360

Data collection

Nonius KappaCCD diffractometer	487 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.053
Graphite monochromator	θmax = 25.9°, θmin = 3.3°
phi–scan	h = −10→10
2809 measured reflections	k = 0→8
854 independent reflections	l = −17→16

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.046	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.147	w = 1/[σ^2(Fo^2) + (0.0911P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.98	(Δ/σ)max = 0.117
854 reflections	Δρmax = 0.15 e Å^−3
102 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.12 (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	0.7802 (3)	0.2500	−0.12775 (17)	0.1135 (11)
O2	0.2604 (2)	0.2500	−0.06743 (17)	0.0800 (8)
O3	0.6065 (2)	0.2500	0.17215 (15)	0.0831 (8)
N1	0.7064 (3)	0.2500	0.02428 (18)	0.0680 (8)
N2	0.5189 (3)	0.2500	−0.09802 (18)	0.0643 (8)
N3	0.4308 (3)	0.2500	0.05727 (18)	0.0662 (8)
C1	0.6763 (4)	0.2500	−0.0694 (2)	0.0714 (9)
C2	0.4045 (3)	0.2500	−0.0326 (2)	0.0600 (8)
C3	0.5849 (3)	0.2500	0.0793 (2)	0.0610 (8)
C4	0.4847 (6)	0.2500	−0.1997 (3)	0.0875 (12)
C5	0.1303 (5)	0.2500	−0.0008 (5)	0.1011 (15)
C6	0.7687 (6)	0.2500	0.2058 (4)	0.1032 (15)
H4A	0.368 (11)	0.2500	−0.205 (5)	0.09 (2)*	0.50
H4B	0.595 (11)	0.2500	−0.222 (6)	0.11 (3)*	0.50
H4C	0.419 (7)	0.129 (9)	−0.212 (3)	0.098 (17)*	0.50
H4D	0.538 (8)	0.116 (10)	−0.222 (4)	0.12 (2)*	0.50
H5A	0.135 (4)	0.130 (5)	0.041 (2)	0.131 (12)*
H5B	0.055 (8)	0.2500	−0.039 (4)	0.16 (2)*
H6A	0.816 (4)	0.127 (5)	0.184 (2)	0.139 (12)*
H6B	0.744 (6)	0.2500	0.270 (4)	0.142 (19)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0681 (18)	0.198 (3)	0.0740 (18)	0.000	0.0150 (13)	0.000
O2	0.0506 (12)	0.0957 (16)	0.0937 (18)	0.000	−0.0162 (12)	0.000
O3	0.0756 (16)	0.1125 (18)	0.0612 (16)	0.000	−0.0091 (12)	0.000
N1	0.0511 (15)	0.0905 (19)	0.0623 (17)	0.000	−0.0050 (12)	0.000
N2	0.0591 (16)	0.0743 (16)	0.0595 (16)	0.000	−0.0077 (12)	0.000
N3	0.0519 (14)	0.0819 (18)	0.0648 (18)	0.000	0.0004 (12)	0.000
C1	0.0547 (18)	0.092 (2)	0.068 (2)	0.000	0.0032 (17)	0.000
C2	0.0481 (17)	0.0610 (18)	0.071 (2)	0.000	−0.0043 (14)	0.000
C3	0.0595 (19)	0.0673 (19)	0.056 (2)	0.000	−0.0054 (15)	0.000
C4	0.091 (3)	0.107 (4)	0.064 (2)	0.000	−0.017 (2)	0.000
C5	0.051 (2)	0.118 (4)	0.134 (4)	0.000	−0.002 (2)	0.000
C6	0.091 (3)	0.135 (4)	0.083 (3)	0.000	−0.029 (2)	0.000

Geometric parameters (Å, º)

O1—C1	1.212 (4)	N3—C2	1.303 (4)
O2—C2	1.317 (3)	N3—C3	1.342 (4)
O2—C5	1.456 (5)	C4—H4A	0.99 (9)
O3—C3	1.338 (4)	C4—H4B	0.99 (9)
O3—C6	1.454 (5)	C4—H4C	1.00 (6)
N1—C3	1.295 (4)	C4—H4D	1.06 (6)
N1—C1	1.362 (4)	C5—H5A	1.01 (3)
N2—C2	1.346 (4)	C5—H5B	0.84 (6)
N2—C1	1.393 (4)	C6—H6A	0.98 (3)
N2—C4	1.480 (4)	C6—H6B	0.93 (6)
C2—O2—C5	117.0 (3)	N2—C4—H4A	106 (4)
C3—O3—C6	117.1 (3)	N2—C4—H4B	98 (5)
C3—N1—C1	116.7 (2)	H4A—C4—H4B	156 (6)
C2—N2—C1	119.0 (3)	N2—C4—H4C	106 (3)
C2—N2—C4	122.7 (3)	H4A—C4—H4C	55 (3)
C1—N2—C4	118.3 (3)	H4B—C4—H4C	118 (4)
C2—N3—C3	113.4 (3)	N2—C4—H4D	102 (3)
O1—C1—N1	122.7 (3)	H4A—C4—H4D	114 (4)
O1—C1—N2	119.5 (3)	H4B—C4—H4D	60 (4)
N1—C1—N2	117.8 (3)	H4C—C4—H4D	60 (4)
N3—C2—O2	122.0 (3)	O2—C5—H5A	111.0 (19)
N3—C2—N2	124.1 (3)	O2—C5—H5B	98 (4)
O2—C2—N2	113.9 (3)	H5A—C5—H5B	115 (2)
N1—C3—O3	119.6 (3)	O3—C6—H6A	106 (2)
N1—C3—N3	129.0 (3)	O3—C6—H6B	96 (3)
O3—C3—N3	111.4 (3)	H6A—C6—H6B	114 (2)
C3—N1—C1—O1	180.0	C1—N2—C2—N3	0.0
C3—N1—C1—N2	0.0	C4—N2—C2—N3	180.0
C2—N2—C1—O1	180.0	C1—N2—C2—O2	180.0
C4—N2—C1—O1	0.0	C4—N2—C2—O2	0.0
C2—N2—C1—N1	0.0	C1—N1—C3—O3	180.0
C4—N2—C1—N1	180.0	C1—N1—C3—N3	0.0
C3—N3—C2—O2	180.0	C6—O3—C3—N1	0.0
C3—N3—C2—N2	0.0	C6—O3—C3—N3	180.0
C5—O2—C2—N3	0.0	C2—N3—C3—N1	0.0
C5—O2—C2—N2	180.0	C2—N3—C3—O3	180.0

HTP(359K) 4,6-Dimethoxy-3-methyl-dihydro-triazine-2-one

Crystal data

C6H9N3O3	Dx = 1.384 Mg m^−3
Mr = 171.16	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 1789 reflections
a = 8.481 (1) Å	θ = 3.7–21.8°
b = 6.780 (1) Å	µ = 0.11 mm^−1
c = 14.284 (2) Å	T = 359 K
V = 821.2 (2) Å^3	Prism, colourless
Z = 4	0.35 × 0.30 × 0.30 mm
F(000) = 360

Data collection

Siemens SMART diffractometer	559 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.030
Graphite monochromator	θmax = 28.3°, θmin = 3.7°
ω scans	h = −11→11
8424 measured reflections	k = −4→5
820 independent reflections	l = −19→8

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.166	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.1167P)^2 + 0.0022P] where P = (Fo^2 + 2Fc^2)/3
820 reflections	(Δ/σ)max = 0.023
73 parameters	Δρmax = 0.25 e Å^−3
0 restraints	Δρmin = −0.18 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	0.7813 (2)	0.2500	−0.12774 (14)	0.1212 (10)
O2	0.26221 (19)	0.2500	−0.06828 (14)	0.0857 (8)
O3	0.60604 (19)	0.2500	0.17173 (12)	0.0899 (8)
N1	0.7066 (2)	0.2500	0.02448 (14)	0.0720 (8)
N2	0.5205 (2)	0.2500	−0.09817 (14)	0.0674 (7)
N3	0.4309 (2)	0.2500	0.05635 (14)	0.0682 (7)
C1	0.6784 (3)	0.2500	−0.06886 (18)	0.0757 (9)
C2	0.4063 (2)	0.2500	−0.03326 (17)	0.0623 (8)
C3	0.5861 (3)	0.2500	0.07951 (16)	0.0639 (8)
C4	0.4864 (4)	0.2500	−0.19964 (18)	0.0929 (10)
H4A	0.5679	0.1790	−0.2321	0.139*	0.50
H4B	0.4828	0.3839	−0.2221	0.139*	0.50
H4C	0.3865	0.1871	−0.2107	0.139*	0.50
C5	0.1321 (3)	0.2500	−0.0014 (3)	0.1072 (12)
H5A	0.1320	0.3726	0.0327	0.161*	0.50
H5B	0.1451	0.1419	0.0416	0.161*	0.50
H5C	0.0338	0.2500	−0.0341	0.161*
C6	0.7664 (4)	0.2500	0.2067 (2)	0.1134 (14)
H6A	0.8290	0.3395	0.1700	0.170*	0.50
H6B	0.8094	0.1189	0.2021	0.170*	0.50
H6C	0.7673	0.2916	0.2710	0.170*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0665 (13)	0.217 (3)	0.0801 (13)	0.000	0.0158 (10)	0.000
O2	0.0508 (9)	0.105 (2)	0.1011 (14)	0.000	−0.0198 (8)	0.000
O3	0.0757 (12)	0.127 (2)	0.0664 (12)	0.000	−0.0059 (9)	0.000
N1	0.0466 (9)	0.100 (2)	0.0693 (13)	0.000	−0.0059 (8)	0.000
N2	0.0586 (11)	0.0793 (19)	0.0642 (12)	0.000	−0.0078 (9)	0.000
N3	0.0506 (10)	0.085 (2)	0.0691 (12)	0.000	0.0004 (8)	0.000
C1	0.0535 (12)	0.099 (3)	0.0749 (17)	0.000	0.0009 (11)	0.000
C2	0.0474 (11)	0.063 (2)	0.0767 (16)	0.000	−0.0086 (10)	0.000
C3	0.0570 (13)	0.070 (2)	0.0642 (14)	0.000	−0.0078 (10)	0.000
C4	0.093 (2)	0.122 (3)	0.0642 (15)	0.000	−0.0131 (13)	0.000
C5	0.0427 (11)	0.136 (3)	0.143 (3)	0.000	0.0001 (14)	0.000
C6	0.094 (2)	0.157 (4)	0.089 (2)	0.000	−0.0413 (17)	0.000

Geometric parameters (Å, º)

O1—C1	1.212 (3)	N3—C3	1.357 (3)
O2—C2	1.320 (2)	C4—H4A	0.9616
O2—C5	1.460 (3)	C4—H4B	0.9633
O3—C3	1.328 (3)	C4—H4C	0.9615
O3—C6	1.449 (3)	C5—H5A	0.9629
N1—C3	1.289 (3)	C5—H5B	0.9624
N1—C1	1.354 (3)	C5—H5C	0.9560
N2—C2	1.341 (3)	C6—H6A	0.9620
N2—C1	1.403 (3)	C6—H6B	0.9632
N2—C4	1.478 (3)	C6—H6C	0.9610
N3—C2	1.297 (3)
C2—O2—C5	116.8 (2)	N2—C4—H4B	109.4
C3—O3—C6	117.5 (2)	H4A—C4—H4B	109.6
C3—N1—C1	117.40 (19)	N2—C4—H4C	109.5
C2—N2—C1	118.9 (2)	H4A—C4—H4C	109.4
C2—N2—C4	122.5 (2)	H4B—C4—H4C	109.6
C1—N2—C4	118.6 (2)	O2—C5—H5A	109.3
C2—N3—C3	113.4 (2)	O2—C5—H5B	109.3
O1—C1—N1	123.8 (2)	H5A—C5—H5B	109.6
O1—C1—N2	118.7 (2)	O2—C5—H5C	109.8
N1—C1—N2	117.5 (2)	H5A—C5—H5C	104.3
N3—C2—O2	121.5 (2)	H5B—C5—H5C	114.3
N3—C2—N2	124.5 (2)	O3—C6—H6A	109.3
O2—C2—N2	114.0 (2)	O3—C6—H6B	109.4
N1—C3—O3	120.2 (2)	H6A—C6—H6B	109.6
N1—C3—N3	128.3 (2)	O3—C6—H6C	109.7
O3—C3—N3	111.4 (2)	H6A—C6—H6C	109.4
N2—C4—H4A	109.4	H6B—C6—H6C	109.5