Bis­(melaminium) terephthalate dihydrate

The crystal structure of the title melaminium salt, bis(2,4,6-tri­amino-1,3,5-triazin-1-ium) terephthalate dihydrate, 2C₃H₇N₆⁺·C₈H₄O₄²⁻·2H₂O, is composed of monoprotonated melaminium cations, terephthalate dianions and water mol­ecules. The protonated melaminium cation and the terephthal­ate anion are almost coplanar, the latter possessing a twofold axis of symmetry. The crystal structure involves extensive N—H...N, N—H...O and O—H...O hydrogen bonding.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.067
• wR factor = 0.174
• Data-to-parameter ratio = 11.0

checkCIF/PLATON results

No syntax errors found



Alert level B
SHFSU01_ALERT_2_B  The absolute value of parameter shift to su ratio > 0.10
            Absolute value of the parameter shift to su ratio given   0.170
            Additional refinement cycles may be required.
PLAT080_ALERT_2_B Maximum Shift/Error ............................       0.17

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor ....       2.48
PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor ....       2.49
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5
PLAT420_ALERT_2_C D-H Without Acceptor       N5     -   H5B    ...          ?
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          3

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   8 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
   5 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
   2 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SMART and SAINT (Siemens,1994); data reduction: XPREP in SHELXTL (Siemens, 1994); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Bis(melaminium) terephthalate dihydrate

Crystal data

2C3H7N6^+·C8H4O4^2^−·2H2O	F(000) = 476
Mr = 454.44	Dx = 1.559 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.809 (4) Å	Cell parameters from 1132 reflections
b = 20.164 (10) Å	θ = 2.0–25.1°
c = 7.062 (6) Å	µ = 0.13 mm^−1
β = 93.33 (5)°	T = 293 K
V = 967.9 (11) Å^3	Prism, colorless
Z = 2	0.20 × 0.16 × 0.15 mm

Data collection

Siemens SMART CCD area-detector diffractometer	1691 independent reflections
Radiation source: fine-focus sealed tube	1215 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
φ and ω scans	θmax = 25.1°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→7
Tmin = 0.975, Tmax = 0.981	k = −22→23
3095 measured reflections	l = −3→8

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)] = 0.067	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.174	w = 1/[σ^2(Fo^2) + (0.0718P)^2 + 1.0433P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.170
1691 reflections	Δρmax = 0.27 e Å^−3
154 parameters	Δρmin = −0.26 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.009 (2)

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
N3	0.2912 (4)	0.69529 (13)	0.4061 (4)	0.0308 (7)
H3A	0.3021	0.7378	0.4113	0.037*
O2	0.3209 (3)	0.82958 (11)	0.4212 (4)	0.0395 (7)
O1	0.6320 (4)	0.82430 (11)	0.5293 (4)	0.0412 (7)
N2	0.4269 (4)	0.59022 (13)	0.4708 (4)	0.0316 (7)
N1	0.0989 (4)	0.60209 (14)	0.3276 (4)	0.0353 (7)
N6	0.6065 (4)	0.68518 (14)	0.5335 (4)	0.0384 (8)
H6A	0.7058	0.6619	0.5750	0.046*
H6B	0.6142	0.7277	0.5326	0.046*
N5	0.2329 (5)	0.50096 (14)	0.3999 (5)	0.0435 (8)
H5A	0.3279	0.4763	0.4439	0.052*
H5B	0.1247	0.4832	0.3561	0.052*
C4	0.4895 (5)	0.93072 (15)	0.4904 (5)	0.0292 (8)
C3	0.4425 (5)	0.65558 (15)	0.4710 (5)	0.0275 (8)
C2	0.2532 (5)	0.56633 (16)	0.3997 (5)	0.0302 (8)
N4	−0.0197 (4)	0.70654 (15)	0.2662 (4)	0.0421 (9)
H4A	−0.1284	0.6901	0.2191	0.050*
H4B	−0.0033	0.7488	0.2700	0.050*
C5	0.3396 (5)	0.97024 (17)	0.4089 (5)	0.0350 (9)
H5C	0.2311	0.9502	0.3464	0.042*
C8	0.6510 (5)	0.96178 (16)	0.5811 (5)	0.0331 (8)
H8A	0.7535	0.9364	0.6354	0.040*
C9	0.4795 (5)	0.85639 (16)	0.4794 (5)	0.0298 (8)
C1	0.1229 (5)	0.66663 (16)	0.3330 (5)	0.0307 (8)
OW	−0.0553 (5)	0.85744 (16)	0.2865 (5)	0.0517 (8)
HW1B	0.065 (8)	0.854 (2)	0.337 (6)	0.067 (14)*
HW1A	−0.127 (9)	0.859 (3)	0.380 (8)	0.11 (2)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N3	0.0289 (15)	0.0153 (14)	0.0476 (18)	−0.0010 (12)	−0.0043 (13)	−0.0005 (12)
O2	0.0291 (14)	0.0205 (13)	0.0680 (18)	−0.0030 (10)	−0.0059 (12)	−0.0004 (11)
O1	0.0340 (14)	0.0195 (13)	0.0681 (18)	0.0029 (11)	−0.0139 (12)	0.0003 (11)
N2	0.0306 (16)	0.0198 (15)	0.0440 (17)	−0.0025 (12)	−0.0023 (13)	0.0007 (12)
N1	0.0302 (16)	0.0235 (16)	0.0512 (19)	−0.0011 (12)	−0.0053 (13)	−0.0037 (13)
N6	0.0312 (17)	0.0203 (15)	0.062 (2)	−0.0030 (12)	−0.0117 (14)	0.0036 (14)
N5	0.0352 (17)	0.0239 (16)	0.069 (2)	−0.0050 (13)	−0.0130 (15)	−0.0016 (14)
C4	0.0289 (18)	0.0222 (17)	0.0364 (19)	−0.0019 (14)	−0.0003 (14)	0.0014 (14)
C3	0.0276 (17)	0.0209 (17)	0.0335 (18)	−0.0017 (15)	−0.0013 (14)	−0.0002 (14)
C2	0.0309 (18)	0.0232 (18)	0.0366 (19)	−0.0001 (15)	0.0020 (15)	−0.0010 (14)
N4	0.0319 (16)	0.0251 (17)	0.067 (2)	−0.0003 (13)	−0.0121 (15)	−0.0001 (14)
C5	0.031 (2)	0.0253 (18)	0.047 (2)	−0.0013 (15)	−0.0087 (16)	−0.0005 (16)
C8	0.0295 (19)	0.0217 (18)	0.047 (2)	0.0016 (15)	−0.0068 (15)	−0.0002 (15)
C9	0.0283 (19)	0.0223 (17)	0.0386 (19)	0.0004 (15)	−0.0010 (14)	−0.0009 (14)
C1	0.0257 (18)	0.0258 (19)	0.040 (2)	−0.0008 (15)	−0.0025 (14)	−0.0030 (15)
OW	0.0345 (17)	0.057 (2)	0.062 (2)	−0.0017 (14)	−0.0100 (15)	−0.0006 (15)

Geometric parameters (Å, º)

N3—C1	1.358 (4)	N5—H5B	0.8600
N3—C3	1.363 (4)	C4—C8	1.389 (5)
N3—H3A	0.8600	C4—C5	1.393 (5)
O2—C9	1.255 (4)	C4—C9	1.502 (5)
O1—C9	1.256 (4)	N4—C1	1.326 (4)
N2—C3	1.322 (4)	N4—H4A	0.8600
N2—C2	1.347 (4)	N4—H4B	0.8600
N1—C1	1.312 (4)	C5—C8^i	1.374 (5)
N1—C2	1.349 (4)	C5—H5C	0.9300
N6—C3	1.320 (4)	C8—C5^i	1.374 (5)
N6—H6A	0.8600	C8—H8A	0.9300
N6—H6B	0.8600	OW—HW1B	0.87 (5)
N5—C2	1.325 (4)	OW—HW1A	0.84 (6)
N5—H5A	0.8600
C1—N3—C3	118.8 (3)	N5—C2—N1	116.9 (3)
C1—N3—H3A	120.6	N2—C2—N1	126.7 (3)
C3—N3—H3A	120.6	C1—N4—H4A	120.0
C3—N2—C2	115.2 (3)	C1—N4—H4B	120.0
C1—N1—C2	115.2 (3)	H4A—N4—H4B	120.0
C3—N6—H6A	120.0	C8^i—C5—C4	121.2 (3)
C3—N6—H6B	120.0	C8^i—C5—H5C	119.4
H6A—N6—H6B	120.0	C4—C5—H5C	119.4
C2—N5—H5A	120.0	C5^i—C8—C4	120.5 (3)
C2—N5—H5B	120.0	C5^i—C8—H8A	119.8
H5A—N5—H5B	120.0	C4—C8—H8A	119.8
C8—C4—C5	118.3 (3)	O1—C9—O2	123.5 (3)
C8—C4—C9	120.4 (3)	O1—C9—C4	117.7 (3)
C5—C4—C9	121.3 (3)	O2—C9—C4	118.8 (3)
N6—C3—N2	121.2 (3)	N1—C1—N4	120.3 (3)
N6—C3—N3	117.1 (3)	N1—C1—N3	122.3 (3)
N2—C3—N3	121.8 (3)	N4—C1—N3	117.4 (3)
N5—C2—N2	116.4 (3)	HW1B—OW—HW1A	105 (5)

Symmetry code: (i) −x+1, −y+2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3A···O2	0.86	1.86	2.717 (4)	179
N6—H6A···OW^ii	0.86	2.18	2.959 (4)	151
N6—H6B···O1	0.86	1.95	2.811 (4)	180
N5—H5A···N2^iii	0.86	2.20	3.055 (4)	175
N4—H4A···O1^iv	0.86	2.07	2.889 (4)	159
N4—H4B···OW	0.86	2.22	3.056 (5)	163
OW—HW1B···O2	0.87 (5)	1.88 (5)	2.738 (4)	168 (4)
OW—HW1A···O1^v	0.84 (6)	2.13 (6)	2.889 (5)	151 (6)

Symmetry codes: (ii) x+1, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) x−1, −y+3/2, z−1/2; (v) x−1, y, z.