Bis[(E)-4-(hydroxy-imino-meth-yl)pyridinium] oxalate.

The formula unit of the title compound, 2C(6)H(7)N(2)O(+)·C(2)O(4) (2-), comprises two symmetry-equivalent 4-(hydroxy-imino-meth-yl)-pyridinium cations on general positions, linked through hydrogen bonding via an oxalate anion that resides on a crystallographic centre of symmetry. The crystal structure consists of infinite chains of cations and oxalate anions directed by O-H⋯O and multicentre N-H⋯O inter-molecular hydrogen-bonding inter-actions.

Related literature

For related literature, see: Martínez-Ripoll & Lorenz (1976a ▶,b ▶).

Experimental

Crystal data

2C6H7N2O+·C2O4 2−

M = 334.30

Monoclinic,

a = 4.8895 (2) Å

b = 15.2920 (5) Å

c = 10.0491 (4) Å

β = 103.967 (4)°

V = 729.16 (5) Å3

Z = 2

Mo Kα radiation

μ = 0.12 mm−1

T = 113 (2) K

0.55 × 0.11 × 0.10 mm

Data collection

Oxford Diffraction Sapphire2 CCD diffractometer

Absorption correction: multi-scan (ABSPACK in CrysAlis RED; Oxford Diffraction, 2006 ▶) T min = 0.856, T max = 0.990

11067 measured reflections

1281 independent reflections

961 reflections with I > 2σ(I)

R int = 0.051

Refinement

R[F 2 > 2σ(F 2)] = 0.032

wR(F 2) = 0.089

S = 1.04

1281 reflections

110 parameters

H-atom parameters constrained

Δρmax = 0.23 e Å−3

Δρmin = −0.23 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2006 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ▶); molecular graphics: DIAMOND (Brandenburg, 2007 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536807064136/gg2061sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807064136/gg2061Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

2C6H7N2O+·C2O42–	F000 = 348
Mr = 334.30	Dx = 1.523 Mg m−3
Monoclinic, P21/c	Melting point: not measured K
Hall symbol: -P 2ybc	Mo Kα radiation λ = 0.71073 Å
a = 4.8895 (2) Å	Cell parameters from 3854 reflections
b = 15.2920 (5) Å	θ = 2.5–36.5º
c = 10.0491 (4) Å	µ = 0.12 mm−1
β = 103.967 (4)º	T = 113 (2) K
V = 729.16 (5) Å3	Needle, colourless
Z = 2	0.55 × 0.11 × 0.10 mm

Oxford Diffraction Sapphire2 CCD diffractometer	1281 independent reflections
Radiation source: Enhance (Mo) X-ray Source	961 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.051
Detector resolution: 8.4171 pixels mm-1	θmax = 25.0º
T = 113(2) K	θmin = 3.4º
ω scans	h = −5→5
Absorption correction: multi-scan(ABSPACK in CrysAlis RED; Oxford Diffraction, 2006)	k = −18→18
Tmin = 0.856, Tmax = 0.990	l = −11→11
11067 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.032	H-atom parameters constrained
wR(F2) = 0.089	w = 1/[σ2(Fo2) + (0.0522P)2 + 0.0471P] where P = (Fo2 + 2Fc2)/3
S = 1.04	(Δ/σ)max < 0.001
1281 reflections	Δρmax = 0.23 e Å−3
110 parameters	Δρmin = −0.23 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

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.

	x	y	z	Uiso*/Ueq
N1	0.6117 (3)	0.60445 (9)	0.71059 (13)	0.0247 (4)
H1	0.7064	0.5883	0.6505	0.030*
N42	0.1137 (3)	0.62604 (9)	1.08097 (13)	0.0241 (3)
C2	0.4916 (3)	0.54332 (11)	0.77268 (16)	0.0243 (4)
H2	0.5118	0.4833	0.7528	0.029*
C3	0.3397 (3)	0.56697 (11)	0.86471 (16)	0.0225 (4)
H3	0.2507	0.5235	0.9072	0.027*
C4	0.3160 (3)	0.65497 (10)	0.89594 (15)	0.0204 (4)
C5	0.4469 (3)	0.71665 (10)	0.83047 (16)	0.0245 (4)
H5	0.4357	0.7771	0.8503	0.029*
C6	0.5916 (3)	0.68968 (11)	0.73751 (16)	0.0257 (4)
H6	0.6787	0.7317	0.6915	0.031*
C41	0.1582 (3)	0.68277 (10)	0.99568 (15)	0.0224 (4)
H41	0.0914	0.7411	0.9966	0.027*
O43	−0.0394 (3)	0.65975 (7)	1.16792 (12)	0.0293 (3)
H43	−0.0141	0.6286	1.2387	0.044*
O71	0.8730 (2)	0.60681 (7)	0.50707 (11)	0.0301 (3)
O72	1.1057 (2)	0.54797 (7)	0.36342 (11)	0.0292 (3)
C7	0.9929 (3)	0.54522 (10)	0.46309 (16)	0.0225 (4)

	U11	U22	U33	U12	U13	U23
O43	0.0383 (7)	0.0282 (7)	0.0282 (7)	0.0070 (5)	0.0211 (6)	0.0022 (5)
N1	0.0233 (8)	0.0312 (8)	0.0215 (7)	0.0015 (6)	0.0089 (6)	−0.0007 (6)
N42	0.0256 (8)	0.0262 (8)	0.0236 (7)	0.0039 (6)	0.0123 (6)	−0.0010 (6)
C2	0.0249 (9)	0.0242 (9)	0.0237 (9)	0.0009 (7)	0.0057 (7)	0.0007 (7)
C3	0.0236 (9)	0.0235 (9)	0.0213 (8)	0.0008 (7)	0.0073 (7)	0.0031 (7)
C4	0.0191 (8)	0.0245 (9)	0.0169 (8)	0.0019 (7)	0.0030 (7)	0.0032 (6)
C5	0.0276 (9)	0.0212 (9)	0.0247 (9)	0.0002 (7)	0.0064 (7)	0.0024 (7)
C6	0.0260 (9)	0.0288 (9)	0.0234 (9)	−0.0033 (8)	0.0080 (7)	0.0035 (7)
C41	0.0242 (9)	0.0218 (9)	0.0220 (9)	0.0027 (7)	0.0072 (7)	−0.0003 (6)
O71	0.0411 (7)	0.0239 (6)	0.0315 (7)	0.0038 (5)	0.0210 (6)	0.0022 (5)
O72	0.0382 (7)	0.0292 (7)	0.0268 (6)	0.0032 (5)	0.0207 (6)	0.0038 (5)
C7	0.0226 (9)	0.0249 (9)	0.0207 (8)	−0.0035 (7)	0.0064 (7)	−0.0019 (7)

O43—N42	1.380 (2)	C4—C5	1.391 (2)
O43—H43	0.8400	C4—C41	1.468 (2)
N1—C2	1.336 (2)	C5—C6	1.364 (2)
N1—C6	1.340 (2)	C5—H5	0.9500
N1—H1	0.8800	C6—H6	0.9500
N42—C41	1.274 (2)	C41—H41	0.9500
C2—C3	1.367 (2)	O71—C7	1.246 (2)
C2—H2	0.9500	O72—C7	1.255 (2)
C3—C4	1.393 (2)	C7—C7i	1.563 (3)
C3—H3	0.9500
N42—O43—H43	109.5	C3—C4—C41	121.31 (14)
C2—N1—C6	121.63 (14)	C6—C5—C4	119.51 (15)
C2—N1—H1	119.2	C6—C5—H5	120.2
C6—N1—H1	119.2	C4—C5—H5	120.2
C41—N42—O43	112.22 (13)	N1—C6—C5	120.53 (15)
N1—C2—C3	120.17 (15)	N1—C6—H6	119.7
N1—C2—H2	119.9	C5—C6—H6	119.7
C3—C2—H2	119.9	N42—C41—C4	117.73 (14)
C2—C3—C4	119.75 (15)	N42—C41—H41	121.1
C2—C3—H3	120.1	C4—C41—H41	121.1
C4—C3—H3	120.1	O71—C7—O72	126.36 (15)
C5—C4—C3	118.40 (15)	O71—C7—C7i	118.13 (17)
C5—C4—C41	120.30 (15)	O72—C7—C7i	115.51 (17)
C6—N1—C2—C3	1.1 (2)	C2—N1—C6—C5	0.2 (2)
N1—C2—C3—C4	−1.5 (2)	C4—C5—C6—N1	−1.0 (2)
C2—C3—C4—C5	0.7 (2)	O43—N42—C41—C4	−179.24 (12)
C2—C3—C4—C41	−179.11 (14)	C5—C4—C41—N42	−159.83 (16)
C3—C4—C5—C6	0.5 (2)	C3—C4—C41—N42	20.0 (2)
C41—C4—C5—C6	−179.66 (14)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O71	0.88	1.84	2.660 (2)	154
N1—H1···O72i	0.88	2.30	2.897 (2)	126
O43—H43···O72ii	0.84	1.76	2.571 (2)	163

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O71	0.88	1.84	2.660 (2)	154
N1—H1⋯O72i	0.88	2.30	2.897 (2)	126
O43—H43⋯O72ii	0.84	1.76	2.571 (2)	163

Symmetry codes: (i) ; (ii) .