An ortho­rhom­bic polymorph of melaminium chloride hemihydrate

Crystals of an ortho­rhom­bic polymorph of 2,4,6-triamino-1,3,5-triazin-1-ium chloride hemihydrate, C₃H₇N₆⁺·Cl⁻·0.5H₂O, were obtained by cocrystallization experiments under aqueous acidic conditions (HCl, pH = 2). In the crystal structure, the melaminium ions, chloride anions and water mol­ecules are linked via hydrogen bonds. All H atoms of the melaminium cation are involved in hydrogen bonds. The chloride anions and the water mol­ecules lie on mirror planes. In the c direction, the melaminium ions are stacked by π–π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 210 K
• Mean [sigma](N-C) = 0.003 Å
• R factor = 0.030
• wR factor = 0.063
• Data-to-parameter ratio = 12.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT027_ALERT_3_B _diffrn_reflns_theta_full (too) Low ............      24.99 Deg.

Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.50 Ratio
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H4     ..  CL1     ..       3.02 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           24.99
           From the CIF: _reflns_number_total               1317
           Count of symmetry unique reflns          722
           Completeness (_total/calc)            182.41%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       595
           Fraction of Friedel pairs measured     0.824
           Are heavy atom types Z>Si present        yes

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

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
   3 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: X-AREA (Stoe & Cie, 2004); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2004); 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); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2001).

2,4,6-triamino-1,3,5-triazin-1-ium chloride hemihydrate

Crystal data

C3H7N6^+·Cl^−·0.5H2O	Dx = 1.576 Mg m^−3
Mr = 171.60	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmc21	Cell parameters from 12019 reflections
a = 16.827 (3) Å	θ = 4.1–58.8°
b = 12.300 (2) Å	µ = 0.47 mm^−1
c = 6.9898 (14) Å	T = 210 K
V = 1446.6 (5) Å^3	Prism, colourless
Z = 8	0.20 × 0.18 × 0.15 mm
F(000) = 712

Data collection

Stoe IPDS-II diffractometer	1186 reflections with I > 2σ(I)
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	Rint = 0.056
Plane graphite monochromator	θmax = 25.0°, θmin = 2.1°
Detector resolution: 6.67 pixels mm^-1	h = −20→20
ω scans	k = −14→14
8913 measured reflections	l = −8→8
1317 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.030	w = 1/[σ^2(Fo^2) + (0.0359P)^2 + 0.2877P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.063	(Δ/σ)max < 0.001
S = 1.04	Δρmax = 0.20 e Å^−3
1317 reflections	Δρmin = −0.21 e Å^−3
105 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.0050 (6)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), with 595 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.11 (8)

Special details

Experimental. The crystal was embedded in perfluoropolyalkylether oil (viscosity 80 cSt.).

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

	x	y	z	Uiso*/Ueq
C1	0.30394 (13)	0.48482 (19)	0.5262 (3)	0.0139 (5)
C2	0.19279 (18)	0.5791 (2)	0.4349 (3)	0.0159 (6)
C3	0.19558 (19)	0.3860 (2)	0.4311 (3)	0.0155 (6)
N1	0.37848 (12)	0.48652 (17)	0.5895 (3)	0.0192 (5)
H11	0.4017	0.5476	0.6112	0.023*
H12	0.4035	0.4265	0.6087	0.023*
N2	0.26773 (12)	0.58257 (14)	0.4987 (3)	0.0163 (4)
N3	0.15133 (14)	0.66879 (18)	0.4087 (3)	0.0232 (5)
H31	0.1724	0.7310	0.4327	0.028*
H32	0.1032	0.6651	0.3676	0.028*
N4	0.15667 (12)	0.48158 (18)	0.3933 (3)	0.0171 (5)
H4	0.1099	0.4806	0.3439	0.020*
N5	0.15709 (15)	0.29388 (18)	0.3989 (3)	0.0231 (5)
H51	0.1800	0.2326	0.4207	0.028*
H52	0.1092	0.2953	0.3562	0.028*
N6	0.26980 (12)	0.38524 (15)	0.4972 (3)	0.0168 (4)
Cl1	0.0000	0.42814 (7)	0.67372 (13)	0.0223 (2)
Cl2	0.0000	0.21806 (7)	0.16106 (14)	0.0243 (2)
O1	0.0000	0.1586 (2)	0.7008 (5)	0.0353 (7)
H1	0.0000	0.171 (4)	0.826 (8)	0.042*
H2	0.0000	0.216 (4)	0.645 (8)	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0115 (10)	0.0164 (11)	0.0138 (11)	−0.0009 (9)	0.0009 (9)	−0.0001 (9)
C2	0.0155 (14)	0.0149 (13)	0.0173 (11)	−0.0005 (11)	0.0028 (9)	−0.0015 (11)
C3	0.0162 (14)	0.0156 (13)	0.0148 (11)	0.0007 (10)	−0.0004 (9)	−0.0017 (10)
N1	0.0132 (10)	0.0132 (10)	0.0312 (11)	0.0015 (8)	−0.0050 (8)	0.0001 (8)
N2	0.0144 (10)	0.0131 (10)	0.0214 (10)	−0.0002 (8)	−0.0002 (8)	−0.0016 (9)
N3	0.0135 (12)	0.0156 (11)	0.0405 (13)	0.0021 (9)	−0.0038 (10)	−0.0045 (10)
N4	0.0117 (10)	0.0175 (12)	0.0220 (12)	0.0005 (9)	−0.0032 (8)	−0.0020 (11)
N5	0.0165 (13)	0.0174 (12)	0.0356 (13)	0.0005 (9)	−0.0048 (9)	0.0006 (11)
N6	0.0140 (10)	0.0159 (10)	0.0207 (10)	−0.0001 (9)	−0.0019 (8)	−0.0017 (9)
Cl1	0.0149 (4)	0.0277 (5)	0.0242 (4)	0.000	0.000	0.0019 (5)
Cl2	0.0138 (4)	0.0221 (4)	0.0369 (5)	0.000	0.000	−0.0084 (4)
O1	0.0415 (16)	0.0221 (15)	0.042 (2)	0.000	0.000	−0.0007 (15)

Geometric parameters (Å, º)

C1—N1	1.330 (3)	N1—H11	0.8600
C1—N2	1.361 (3)	N1—H12	0.8600
C1—N6	1.368 (3)	N3—H31	0.8600
C2—N3	1.318 (4)	N3—H32	0.8600
C2—N2	1.338 (4)	N4—H4	0.8600
C2—N4	1.375 (4)	N5—H51	0.8600
C3—N5	1.325 (4)	N5—H52	0.8600
C3—N6	1.332 (4)	O1—H1	0.89 (5)
C3—N4	1.371 (3)	O1—H2	0.81 (6)
N1—C1—N2	117.1 (2)	C2—N2—C1	116.1 (2)
N1—C1—N6	117.3 (2)	C2—N3—H31	120.0
N2—C1—N6	125.59 (19)	C2—N3—H32	120.0
N3—C2—N2	121.2 (3)	H31—N3—H32	120.0
N3—C2—N4	117.8 (2)	C2—N4—C3	119.7 (2)
N2—C2—N4	121.0 (2)	C2—N4—H4	120.1
N5—C3—N6	120.7 (2)	C3—N4—H4	120.1
N5—C3—N4	117.9 (3)	C3—N5—H51	120.0
N6—C3—N4	121.4 (2)	C3—N5—H52	120.0
C1—N1—H11	120.0	H51—N5—H52	120.0
C1—N1—H12	120.0	C3—N6—C1	116.0 (2)
H11—N1—H12	120.0	H1—O1—H2	109 (5)
N3—C2—N2—C1	178.0 (2)	N5—C3—N4—C2	176.3 (2)
N4—C2—N2—C1	−2.4 (3)	N6—C3—N4—C2	−4.0 (3)
N1—C1—N2—C2	180.0 (2)	N5—C3—N6—C1	−179.8 (2)
N6—C1—N2—C2	−1.1 (3)	N4—C3—N6—C1	0.6 (3)
N3—C2—N4—C3	−175.4 (2)	N1—C1—N6—C3	−179.0 (2)
N2—C2—N4—C3	5.0 (3)	N2—C1—N6—C3	2.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H12···Cl2^i	0.86	2.44	3.281 (2)	167
N1—H11···O1^ii	0.86	2.23	3.044 (3)	157
N3—H32···Cl1^iii	0.86	2.48	3.256 (2)	150
N3—H31···N6^iv	0.86	2.18	3.038 (3)	178
N4—H4···Cl1^iii	0.86	2.47	3.246 (2)	151
N4—H4···Cl1	0.86	3.02	3.350 (2)	105
N5—H52···Cl2	0.86	2.48	3.259 (2)	152
N5—H51···N2^v	0.86	2.12	2.974 (3)	175
O1—H1···Cl2^vi	0.89 (5)	2.41 (5)	3.300 (4)	176 (4)
O1—H2···Cl1	0.81 (6)	2.61 (5)	3.321 (3)	147 (5)

Symmetry codes: (i) −x+1/2, −y+1/2, z+1/2; (ii) x+1/2, y+1/2, z; (iii) −x, −y+1, z−1/2; (iv) −x+1/2, y+1/2, z; (v) −x+1/2, y−1/2, z; (vi) x, y, z+1.