Melaminium formate

Crystals of a new melaminium salt, 2,4,6-tri­amino-1,3,5-triazin-1-ium formate, C₃H₇N₆⁺·CHO₂⁻, consist of singly protonated melaminium residues and formate anions. The components are linked by hydrogen bonds into a three-dimensional framework structure. The melaminium residues are interconnected by two pairs of N—H...N hydrogen bonds into chains in the form of stacks, with a distance of 3.34 (1) Å between the triazine rings, clearly indicating π–π interactions. The chains of melaminium residues are interconnected via N—H...O hydrogen bonds by the formate anions, forming a non-covalent superstructure.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](O-C) = 0.001 Å
• R factor = 0.036
• wR factor = 0.096
• Data-to-parameter ratio = 16.9

checkCIF/PLATON results

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Computing details

Data collection: KM-4 CCD Software (Kuma, 2001); cell refinement: KM-4 CCD Software; data reduction: KM-4 CCD Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1990); software used to prepare material for publication: SHELXL97.

Melaminium formate

Crystal data

C3H7N6^+·CHO2^−	F(000) = 360
Mr = 172.16	Dx = 1.600 Mg m^−3 Dm = 1.60 (1) Mg m^−3 Dm measured by floatation in chloroform/bromoform
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1252 reflections
a = 3.957 (1) Å	θ = 3.1–29.5°
b = 15.798 (3) Å	µ = 0.13 mm^−1
c = 11.461 (2) Å	T = 295 K
β = 94.14 (1)°	Parallelepiped, colourless
V = 714.6 (3) Å^3	0.36 × 0.20 × 0.12 mm
Z = 4

Data collection

Kuma KM-4 with CCD area-detector diffractometer	1840 independent reflections
Radiation source: fine-focus sealed tube	1300 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.018
Detector resolution: 1024 x 1024 with blocks 2 x 2 pixels mm^-1	θmax = 29.5°, θmin = 3.1°
ω scans	h = −5→4
Absorption correction: analytical [face-indexed; SHELXTL (Sheldrick, 1990)]	k = −21→21
Tmin = 0.950, Tmax = 0.984	l = −15→15
8423 measured reflections

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.057P)^2] where P = (Fo^2 + 2Fc^2)/3
1840 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.23 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
O1	0.1135 (2)	0.50059 (5)	0.31401 (7)	0.0392 (2)
O2	0.3259 (2)	0.49984 (5)	0.13841 (7)	0.0382 (2)
C1	0.2787 (3)	0.53078 (7)	0.23547 (9)	0.0331 (3)
H2	0.3793	0.5831	0.2515	0.040*
N1	0.0197 (2)	0.34890 (5)	0.09196 (7)	0.0262 (2)
H1	0.0927	0.3994	0.1062	0.031*
N2	−0.2590 (2)	0.22705 (6)	0.15420 (7)	0.0274 (2)
N3	−0.0349 (2)	0.23285 (5)	−0.03535 (7)	0.0269 (2)
N4	−0.2942 (2)	0.11420 (6)	0.02892 (7)	0.0320 (2)
H41	−0.3955	0.0866	0.0808	0.038*
H42	−0.2576	0.0906	−0.0366	0.038*
N5	−0.2131 (3)	0.34656 (6)	0.26877 (7)	0.0338 (2)
H51	−0.3216	0.3219	0.3215	0.041*
H52	−0.1434	0.3978	0.2792	0.041*
N6	0.2457 (2)	0.35239 (6)	−0.08704 (8)	0.0343 (2)
H61	0.2851	0.3293	−0.1526	0.041*
H62	0.3173	0.4028	−0.0711	0.041*
C2	0.0750 (2)	0.31042 (7)	−0.01060 (8)	0.0246 (2)
C3	−0.1539 (2)	0.30613 (6)	0.17235 (8)	0.0249 (2)
C4	−0.1949 (2)	0.19302 (6)	0.04982 (8)	0.0241 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0535 (5)	0.0312 (5)	0.0349 (4)	−0.0078 (4)	0.0168 (4)	−0.0029 (3)
O2	0.0511 (5)	0.0324 (5)	0.0324 (4)	−0.0079 (4)	0.0130 (4)	−0.0038 (3)
C1	0.0424 (6)	0.0266 (6)	0.0304 (6)	−0.0073 (5)	0.0044 (5)	−0.0016 (4)
N1	0.0344 (5)	0.0198 (4)	0.0251 (4)	−0.0030 (3)	0.0067 (4)	−0.0008 (3)
N2	0.0345 (5)	0.0251 (5)	0.0233 (4)	−0.0021 (4)	0.0076 (4)	0.0000 (3)
N3	0.0336 (5)	0.0235 (5)	0.0243 (4)	−0.0004 (4)	0.0076 (4)	−0.0004 (3)
N4	0.0475 (6)	0.0254 (5)	0.0241 (4)	−0.0054 (4)	0.0095 (4)	−0.0013 (4)
N5	0.0521 (6)	0.0242 (5)	0.0268 (5)	−0.0059 (4)	0.0137 (4)	−0.0020 (4)
N6	0.0467 (6)	0.0262 (5)	0.0323 (5)	−0.0044 (4)	0.0176 (4)	0.0004 (4)
C2	0.0268 (5)	0.0232 (5)	0.0242 (5)	0.0035 (4)	0.0043 (4)	0.0023 (4)
C3	0.0286 (5)	0.0231 (5)	0.0232 (5)	0.0019 (4)	0.0036 (4)	0.0018 (4)
C4	0.0263 (5)	0.0226 (5)	0.0235 (5)	0.0015 (4)	0.0034 (4)	0.0011 (4)

Geometric parameters (Å, º)

O1—C1	1.2448 (12)	N4—C4	1.3224 (13)
O2—C1	1.2416 (12)	N4—H41	0.8600
C1—H2	0.9300	N4—H42	0.8600
N1—C2	1.3550 (12)	N5—C3	1.3120 (12)
N1—C3	1.3670 (12)	N5—H51	0.8600
N1—H1	0.8600	N5—H52	0.8600
N2—C3	1.3283 (13)	N6—C2	1.3225 (13)
N2—C4	1.3522 (12)	N6—H61	0.8600
N3—C2	1.3241 (13)	N6—H62	0.8600
N3—C4	1.3560 (12)
O2—C1—O1	128.16 (10)	H51—N5—H52	120.0
O2—C1—H2	115.9	C2—N6—H61	120.0
O1—C1—H2	115.9	C2—N6—H62	120.0
C2—N1—C3	118.90 (9)	H61—N6—H62	120.0
C2—N1—H1	120.5	N6—C2—N3	119.84 (9)
C3—N1—H1	120.5	N6—C2—N1	118.15 (10)
C3—N2—C4	115.84 (9)	N3—C2—N1	122.01 (9)
C2—N3—C4	116.00 (8)	N5—C3—N2	121.12 (9)
C4—N4—H41	120.0	N5—C3—N1	117.13 (9)
C4—N4—H42	120.0	N2—C3—N1	121.75 (9)
H41—N4—H42	120.0	N4—C4—N2	117.53 (9)
C3—N5—H51	120.0	N4—C4—N3	117.05 (8)
C3—N5—H52	120.0	N2—C4—N3	125.42 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2	0.86	1.86	2.7100 (12)	170
N5—H52···O1	0.86	1.94	2.7863 (13)	167
N4—H41···O1^i	0.86	2.05	2.8959 (12)	169
N4—H42···O1^ii	0.86	2.27	3.0593 (12)	153
N5—H51···N3^iii	0.86	2.09	2.9408 (13)	173
N6—H61···N2^iv	0.86	2.38	3.2191 (14)	165
N6—H62···O2^v	0.86	2.26	2.9690 (13)	140

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