3,4-Diamino­pyridinium hydrogen squarate

Anions and cations of the title compound, C₅H₈N₃⁺·C₄HO₄⁻, are connected by moderately strong inter­molecular N—H...O hydrogen bonds into an infinite three-dimensional network. Hydrogen squarate anions form dimers through strong O—H...O inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.066
• wR factor = 0.189
• Data-to-parameter ratio = 11.0

checkCIF/PLATON results

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Alert level C
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C3'    -   C4'     ..       5.70 su
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.57

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

   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
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S1. Comment

In the course of our spectroscopic and structural studies of pyridine derivatives (Kolev et al., 2004; Kolev, Wortmann et al.,2005; Kolev, Fiser et al., 2005; Kolev et al., 2007), the crystal structure of 3,4-diaminopyridinium hydrogensquarate is reported. Its molecular structure is depicted in Fig. 1. The crystal structure consists of chains of cations and anions connected by moderate hydrogen bonds (Fig. 2) with N···O lengths of 2.799 (4), 2.972 (4) and 2.973 (4) Å, respectively. Hydrogensquarate anions are linked into centrosymmetric dimers by strong O—H···O [O···O = 2.539 (3) Å] interactions.

Related literature

For related literature, see: Kolev et al. (2004, 2007); Kolev, Fiser et al. (2005); Kolev, Wortmann et al. (2005).

S2. Experimental

3,4-diaminopyridinium hydrogensquarate was obtained by mixing an equimolar ratio of 3,4-diaminopyridine (Merck) and squaric acid (Sigma-Aldrich) in 10 ml e thanol. Suitable crystals for X-ray analysis, were grown by allowing the solution to slowly evaporate for 10 days, and were subsequently filtered off, washed with methanol and dried under air.

S3. Refinement

H atoms were constrained to idealized positions and refined using a riding model, with C—H distances of 0.93 Å [U_iso(H) = 1.2 U_iso(C)], NH distances of 0.86 Å [U_iso(H) = 1.5 U_iso(N) and O—H distances of 0.82 Å [U_iso(H) = 1.5 U_iso(O)].

Computing details

Data collection: R3m/V (Siemens, 1989); cell refinement: R3m/V; data reduction: XDISK (Siemens, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1995); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Hydrogen bonding between the anions and cations of (I).

3,4-Diaminopyridinium hydrogen squarate

Crystal data

C5H8N3^+·C4HO4^−	F(000) = 464
Mr = 223.19	Dx = 1.529 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 27 reflections
a = 10.069 (2) Å	θ = 7.5–15°
b = 7.1925 (14) Å	µ = 0.12 mm^−1
c = 13.480 (3) Å	T = 294 K
β = 96.56 (3)°	Prsim, colourless
V = 969.8 (3) Å^3	0.58 × 0.48 × 0.46 mm
Z = 4

Data collection

Siemens P4 four-circle diffractometer	1172 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.044
Graphite monochromator	θmax = 25.0°, θmin = 2.0°
ω scans	h = −1→11
Absorption correction: ψ scan (XPREP; Sheldrick, 1995)	k = −1→8
Tmin = 0.844, Tmax = 0.938	l = −16→16
2310 measured reflections	3 standard reflections every 100 reflections
1698 independent reflections	intensity decay: 1%

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)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.189	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0946P)^2 + 0.5492P] where P = (Fo^2 + 2Fc^2)/3
1698 reflections	(Δ/σ)max = 0.001
154 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.38 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
N1	0.7328 (3)	0.3740 (5)	1.0145 (2)	0.0559 (9)
H1	0.6586	0.3990	1.0375	0.067*
C2	0.8249 (3)	0.2759 (5)	1.0705 (3)	0.0520 (9)
H2	0.8086	0.2368	1.1338	0.062*
C3	0.9425 (3)	0.2325 (5)	1.0359 (2)	0.0472 (9)
H3	1.0057	0.1624	1.0754	0.057*
N2	1.0874 (2)	0.2506 (4)	0.9064 (2)	0.0498 (8)
H21	1.1031	0.2865	0.8480	0.060*
H22	1.1465	0.1877	0.9434	0.060*
C4	0.9699 (3)	0.2929 (5)	0.9401 (2)	0.0400 (8)
N3	0.8886 (3)	0.4537 (5)	0.7857 (2)	0.0568 (9)
H31	0.8270	0.5150	0.7503	0.068*
H32	0.9620	0.4277	0.7619	0.068*
C5	0.8693 (3)	0.3965 (5)	0.8816 (2)	0.0403 (8)
C6	0.7522 (3)	0.4362 (5)	0.9219 (3)	0.0511 (9)
H6	0.6860	0.5061	0.8854	0.061*
C1'	0.2926 (3)	0.0429 (5)	0.2041 (2)	0.0429 (8)
O1'	0.1804 (2)	0.0879 (4)	0.22347 (18)	0.0579 (8)
C2'	0.3618 (3)	0.0417 (5)	0.1124 (2)	0.0417 (8)
O2'	0.3283 (2)	0.0894 (4)	0.02326 (16)	0.0519 (7)
C3'	0.4780 (3)	−0.0317 (5)	0.1697 (2)	0.0414 (8)
O3'	0.5998 (2)	−0.0799 (4)	0.15119 (17)	0.0576 (8)
H3'	0.6030	−0.0814	0.0907	0.086*
C4'	0.4173 (3)	−0.0327 (5)	0.2619 (3)	0.0465 (9)
O4'	0.4548 (2)	−0.0753 (4)	0.34977 (18)	0.0589 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0358 (14)	0.072 (2)	0.062 (2)	−0.0045 (15)	0.0139 (13)	−0.0134 (18)
C2	0.049 (2)	0.060 (2)	0.048 (2)	−0.0107 (18)	0.0109 (16)	−0.0025 (18)
C3	0.0440 (17)	0.052 (2)	0.0449 (19)	−0.0018 (16)	0.0021 (14)	−0.0001 (17)
N2	0.0357 (14)	0.063 (2)	0.0504 (17)	0.0070 (13)	0.0061 (12)	0.0012 (15)
C4	0.0335 (15)	0.0413 (18)	0.0444 (18)	−0.0026 (14)	0.0012 (13)	−0.0080 (15)
N3	0.0509 (17)	0.076 (2)	0.0430 (17)	0.0126 (16)	0.0020 (13)	0.0090 (16)
C5	0.0364 (16)	0.0447 (19)	0.0389 (17)	−0.0023 (14)	−0.0003 (13)	−0.0048 (15)
C6	0.0375 (17)	0.056 (2)	0.058 (2)	0.0015 (16)	−0.0040 (15)	−0.0087 (19)
C1'	0.0296 (15)	0.053 (2)	0.0465 (18)	−0.0003 (14)	0.0043 (13)	−0.0021 (16)
O1'	0.0304 (11)	0.090 (2)	0.0544 (14)	0.0110 (12)	0.0107 (10)	0.0002 (14)
C2'	0.0284 (15)	0.053 (2)	0.0438 (18)	0.0011 (14)	0.0040 (13)	−0.0060 (16)
O2'	0.0322 (11)	0.0770 (18)	0.0462 (14)	0.0142 (11)	0.0023 (9)	−0.0022 (13)
C3'	0.0277 (14)	0.056 (2)	0.0415 (18)	0.0034 (14)	0.0076 (12)	−0.0001 (16)
O3'	0.0303 (11)	0.094 (2)	0.0500 (14)	0.0170 (12)	0.0092 (10)	0.0092 (14)
C4'	0.0272 (15)	0.059 (2)	0.053 (2)	0.0003 (15)	0.0026 (14)	−0.0006 (18)
O4'	0.0330 (12)	0.095 (2)	0.0495 (14)	0.0065 (12)	0.0070 (10)	0.0134 (14)

Geometric parameters (Å, º)

N1—C2	1.330 (5)	N3—H32	0.8600
N1—C6	1.360 (5)	C5—C6	1.383 (4)
N1—H1	0.8600	C6—H6	0.9300
C2—C3	1.358 (5)	C1'—O1'	1.232 (4)
C2—H2	0.9300	C1'—C2'	1.486 (4)
C3—C4	1.420 (5)	C1'—C4'	1.501 (4)
C3—H3	0.9300	C2'—O2'	1.259 (4)
N2—C4	1.349 (4)	C2'—C3'	1.427 (4)
N2—H21	0.8600	C3'—O3'	1.325 (3)
N2—H22	0.8600	C3'—C4'	1.446 (4)
C4—C5	1.421 (4)	O3'—H3'	0.8200
N3—C5	1.391 (4)	C4'—O4'	1.241 (4)
N3—H31	0.8600
C2—N1—C6	122.1 (3)	C6—C5—C4	118.4 (3)
C2—N1—H1	118.9	N3—C5—C4	120.3 (3)
C6—N1—H1	118.9	N1—C6—C5	120.7 (3)
N1—C2—C3	120.4 (3)	N1—C6—H6	119.7
N1—C2—H2	119.8	C5—C6—H6	119.7
C3—C2—H2	119.8	O1'—C1'—C2'	134.9 (3)
C2—C3—C4	120.7 (3)	O1'—C1'—C4'	135.9 (3)
C2—C3—H3	119.7	C2'—C1'—C4'	89.2 (2)
C4—C3—H3	119.7	O2'—C2'—C3'	137.0 (3)
C4—N2—H21	120.0	O2'—C2'—C1'	133.8 (3)
C4—N2—H22	120.0	C3'—C2'—C1'	89.2 (3)
H21—N2—H22	120.0	O3'—C3'—C2'	135.6 (3)
N2—C4—C5	121.9 (3)	O3'—C3'—C4'	130.7 (3)
N2—C4—C3	120.4 (3)	C2'—C3'—C4'	93.8 (2)
C5—C4—C3	117.7 (3)	C3'—O3'—H3'	109.5
C5—N3—H31	120.0	O4'—C4'—C3'	135.2 (3)
C5—N3—H32	120.0	O4'—C4'—C1'	136.9 (3)
H31—N3—H32	120.0	C3'—C4'—C1'	87.9 (3)
C6—C5—N3	121.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3′—H3′···O2′^i	0.82	1.76	2.539 (3)	159
N2—H21···O1′^ii	0.86	2.13	2.972 (4)	166
N1—H1···O4′^iii	0.86	2.01	2.799 (4)	152
N2—H22···O2′^iv	0.86	2.14	2.973 (3)	164

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