2,6-Xylidinium nitrate

The structure of the title organic–inorganic hybrid material, C₈H₁₂N⁺·NO₃⁻, results mainly from electrostatic inter­actions and bifurcated N—H...O and C—H...O hydrogen bonds. Organic 2,6-xylidinium cations and inorganic nitrate anions inter­act to form a three-dimensional hydrogen-bond network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.037
• wR factor = 0.112
• Data-to-parameter ratio = 12.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

Hybrid compounds are widely investigated due to their special relevance in fundamental sciences and in several applied fields such as biomolecular sciences, catalysis and nonlinear optics (Xiao et al., 2005, Yuan et al., 2006). These materials are generally rich in hydrogen bonds which are considered as the most effective tool for constructing sophisticated assemblies from discrete ionic or molecular building blocks due to its strength and directionality (Wang & Zhang, 2006). In this paper, we report the synthesis and structure of a new organic nitrate. Single-crystal X-ray diffraction study of the title compounds shows that the asymmetric unit corresponds to the formula unit (I) which is made of one NO₃^- anion and one 2,6-xylidinium cation (Fig. 1). As well as electrostatic and van der Walls forces, two types of hydrogen bonds (Table 1) participate to define the crystal packing. The first one, N–H···O bonds links ammonium groups and nitrate anions into infinite layers propagating in the (b, c) plane (Fig. 2, Table 1). The second H-bonds type, C–H···O bonds, identified by PLATON (Spek, 2003), connects the successive layers to form a three-dimensional network (Fig. 3, Table 1). It is noteworthy that two hydrogen atoms of the NH₃ groups form bifurcated hydrogen bonds with the nitrate oxygen atoms. Bond lengths and angles observed in this structure agree well with those reported for nitrate or xylidinium compounds (Hemissi et al., 2001, Perpétuo & Janczak, 2004).

Related literature

For general background, see: Xiao et al. (2005); Yuan et al. (2006); Wang & Zhang (2006). For related structures, see: Hemissi et al. (2001); Perpétuo & Janczak (2004).

For related literature, see: Spek (2003).

S2. Experimental

An ethanolic 2,6-xylidinium solution (5 mmol, in 5 ml) was added to an aqueous HNO₃ solution (0.5 M, 10 ml). The obtained solution is evaporated during several days in ambient condition until the formation of single crystals of the title compound (I).

S3. Refinement

All H atoms were positioned geometrically and treated as riding on their parent atoms, [N–H = 0.89, C–H =0.96 Å (CH₃ ) with U_iso(H) = 1.5Ueq and C–H =0.96 Å (Ar–H), with U_iso(H) = 1.5Ueq]

Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); 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: WinGX (Farrugia, 1999).

Figures

	Fig. 1. ORTEP-3 (Farrugia, 1997) view of (I) with atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level·H atoms are represented as small spheres of arbitrary radii. N—H···O hydrogen bonds are shown as dashed lines
	Fig. 2. Detail of a part of (011) hydrogen-bonded layer of NO3- anion and ammonium groups in (I), with H-bonds indicated by dashed lines.
	Fig. 3. Projection of (I) along b axis.

2,6-Xylidinium nitrate

Crystal data

C8H12N^+·NO3^−	F(000) = 392
Mr = 184.20	Dx = 1.367 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 7.891 (2) Å	θ = 8.3–9.7°
b = 8.328 (3) Å	µ = 0.11 mm^−1
c = 13.628 (2) Å	T = 293 K
β = 91.47 (2)°	Parallelepiped, colourless
V = 895.2 (4) Å^3	0.20 × 0.19 × 0.17 mm
Z = 4

Data collection

Enraf–Nonius TurboCAD-4 diffractometer	Rint = 0.018
Radiation source: X-ray tube	θmax = 25.0°, θmin = 2.6°
Graphite monochromator	h = −9→9
non–profiled ω scans	k = 0→9
3131 measured reflections	l = −16→16
1568 independent reflections	2 standard reflections every 120 min
1181 reflections with I > 2σ(I)	intensity decay: 5%

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)] = 0.037	H-atom parameters constrained
wR(F^2) = 0.112	w = 1/[σ^2(Fo^2) + (0.0537P)^2 + 0.2838P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.005
1568 reflections	Δρmax = 0.17 e Å^−3
122 parameters	Δρmin = −0.16 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: 0.014 (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	0.05197 (19)	0.23434 (19)	0.13088 (12)	0.0375 (4)
O1	−0.01610 (19)	0.19181 (19)	0.20863 (10)	0.0535 (4)
O2	0.0066 (2)	0.16522 (19)	0.05302 (10)	0.0548 (4)
O3	0.1585 (2)	0.3402 (2)	0.13256 (13)	0.0701 (5)
N2	0.16555 (19)	0.37350 (19)	0.36594 (11)	0.0379 (4)
C1	0.3441 (2)	0.3220 (2)	0.37321 (12)	0.0318 (4)
C2	0.4727 (2)	0.4356 (2)	0.37051 (12)	0.0366 (5)
C3	0.6386 (3)	0.3782 (3)	0.37620 (14)	0.0465 (5)
C4	0.6726 (3)	0.2168 (3)	0.38574 (15)	0.0465 (5)
C5	0.5416 (2)	0.1077 (3)	0.38996 (13)	0.0418 (5)
C6	0.3738 (2)	0.1575 (2)	0.38346 (12)	0.0341 (4)
C7	0.4382 (3)	0.6136 (3)	0.36478 (15)	0.0487 (5)
C8	0.2319 (3)	0.0377 (2)	0.38770 (16)	0.0466 (5)
H2A	0.1609	0.4793	0.3569	0.057*
H2B	0.1138	0.3482	0.4211	0.057*
H2C	0.1142	0.3241	0.3155	0.057*
H3	0.7282	0.4505	0.3735	0.056*
H4	0.7843	0.1812	0.3894	0.056*
H5	0.5660	−0.0010	0.3973	0.050*
H7A	0.3797	0.6471	0.4222	0.073*
H7B	0.3693	0.6363	0.3074	0.073*
H7C	0.5436	0.6706	0.3611	0.073*
H8A	0.2780	−0.0678	0.3983	0.070*
H8B	0.1677	0.0395	0.3269	0.070*
H8C	0.1592	0.0647	0.4407	0.070*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0347 (8)	0.0315 (9)	0.0462 (10)	0.0017 (7)	−0.0007 (7)	0.0007 (7)
O1	0.0636 (10)	0.0570 (10)	0.0401 (8)	−0.0097 (8)	0.0044 (7)	0.0044 (7)
O2	0.0665 (10)	0.0575 (10)	0.0406 (8)	−0.0133 (8)	0.0043 (7)	−0.0105 (7)
O3	0.0585 (10)	0.0629 (11)	0.0889 (13)	−0.0317 (9)	0.0005 (8)	−0.0011 (9)
N2	0.0408 (9)	0.0321 (9)	0.0406 (8)	0.0074 (7)	−0.0005 (7)	−0.0025 (7)
C1	0.0351 (9)	0.0334 (10)	0.0268 (8)	0.0049 (8)	0.0003 (7)	−0.0013 (7)
C2	0.0457 (12)	0.0355 (11)	0.0285 (9)	−0.0019 (8)	0.0010 (7)	0.0000 (8)
C3	0.0408 (11)	0.0530 (13)	0.0456 (11)	−0.0093 (10)	0.0021 (9)	0.0011 (10)
C4	0.0355 (11)	0.0572 (14)	0.0470 (12)	0.0085 (10)	0.0015 (8)	0.0018 (10)
C5	0.0473 (12)	0.0388 (11)	0.0393 (10)	0.0132 (10)	0.0006 (8)	0.0007 (9)
C6	0.0397 (10)	0.0318 (10)	0.0307 (9)	0.0043 (8)	0.0005 (7)	−0.0014 (7)
C8	0.0510 (13)	0.0319 (11)	0.0565 (12)	−0.0003 (9)	−0.0046 (9)	0.0006 (9)
C7	0.0655 (14)	0.0348 (11)	0.0457 (11)	−0.0052 (11)	0.0014 (10)	0.0026 (9)

Geometric parameters (Å, º)

O1—N1	1.251 (2)	C6—C8	1.502 (3)
O2—N1	1.251 (2)	C1—C2	1.389 (3)
N1—O3	1.218 (2)	C2—C7	1.508 (3)
N2—C1	1.473 (2)	C8—H8A	0.9600
N2—H2A	0.8900	C8—H8B	0.9600
N2—H2B	0.8900	C8—H8C	0.9600
N2—H2C	0.8900	C4—C5	1.379 (3)
C3—C4	1.376 (3)	C4—H4	0.9300
C3—C2	1.394 (3)	C5—H5	0.9300
C3—H3	0.9300	C7—H7A	0.9600
C6—C5	1.388 (3)	C7—H7B	0.9600
C6—C1	1.396 (3)	C7—H7C	0.9600
O3—N1—O1	120.00 (17)	C3—C2—C7	120.52 (19)
O3—N1—O2	122.10 (17)	C6—C8—H8A	109.5
O1—N1—O2	117.90 (16)	C6—C8—H8B	109.5
C1—N2—H2A	109.5	H8A—C8—H8B	109.5
C1—N2—H2B	109.5	C6—C8—H8C	109.5
H2A—N2—H2B	109.5	H8A—C8—H8C	109.5
C1—N2—H2C	109.5	H8B—C8—H8C	109.5
H2A—N2—H2C	109.5	C3—C4—C5	120.22 (19)
H2B—N2—H2C	109.5	C3—C4—H4	119.9
C4—C3—C2	121.37 (19)	C5—C4—H4	119.9
C4—C3—H3	119.3	C4—C5—C6	121.0 (2)
C2—C3—H3	119.3	C4—C5—H5	119.5
C5—C6—C1	117.22 (18)	C6—C5—H5	119.5
C5—C6—C8	120.64 (18)	C2—C7—H7A	109.5
C1—C6—C8	122.14 (17)	C2—C7—H7B	109.5
C2—C1—C6	123.39 (17)	H7A—C7—H7B	109.5
C2—C1—N2	119.84 (17)	C2—C7—H7C	109.5
C6—C1—N2	116.77 (16)	H7A—C7—H7C	109.5
C1—C2—C3	116.78 (18)	H7B—C7—H7C	109.5
C1—C2—C7	122.68 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O1^i	0.89	2.28	3.064 (2)	147
N2—H2A···O2^i	0.89	2.40	3.007 (2)	126
N2—H2B···O2^ii	0.89	2.01	2.888 (2)	169
N2—H2C···O1	0.89	2.08	2.964 (2)	174
N2—H2C···O3	0.89	2.53	3.192 (3)	132
C5—H5···O3^iii	0.93	2.59	3.270 (3)	131
C8—H8B···O1	0.96	2.49	3.345 (3)	149

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