Three-centre hydrogen bonds in 4-picoline N-oxide–hydro­quinone (1/1)

The title compound, C₆H₇NO·C₆H₆O₂, belongs to a series of mol­ecular systems based on methylpyridine N-oxides. The N-oxide molecule is located on a crystallographic twofold rotation axis, while the hydroquinone molecule is located on an inversion centre. The two components are linked by an O—H...O hydrogen bond with a distance of 2.675 (2) Å. In the crystalline environment, three-centre hydrogen bonds involving the N-oxide O atom with two hydro­quinone mol­ecules related by symmetry in the [001] direction are observed.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.037
• wR factor = 0.107
• Data-to-parameter ratio = 13.3

checkCIF/PLATON results

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Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: SDP (Frenz, 1978); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

4-picoline N-oxide–hydroquinone (1/1)

Crystal data

C6H7NO·C6H6O2	F(000) = 464
Mr = 219.23	Dx = 1.286 Mg m^−3
Monoclinic, C2/c	Melting point: 395(1) K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 13.0486 (2) Å	Cell parameters from 25 reflections
b = 11.2091 (2) Å	θ = 2.9–26.3°
c = 9.0905 (3) Å	µ = 0.09 mm^−1
β = 121.625 (2)°	T = 291 K
V = 1132.16 (5) Å^3	Prism, colorless
Z = 4	0.25 × 0.20 × 0.12 mm

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.019
Radiation source: fine-focus sealed tube	θmax = 26.3°, θmin = 2.9°
Graphite monochromator	h = −16→0
ω/2θ scans	k = 0→13
1191 measured reflections	l = −9→11
1145 independent reflections	2 standard reflections every 120 min
767 reflections with I > 2σ(I)	intensity decay: 0.1%

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) = 0.107	w = 1/[σ^2(Fo^2) + (0.0275P)^2 + 0.8305P] where P = (Fo^2 + 2Fc^2)/3
S = 1.11	(Δ/σ)max < 0.001
1145 reflections	Δρmax = 0.18 e Å^−3
86 parameters	Δρmin = −0.15 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 (1)

Special details

Experimental. IR spectra were recorded on a ATI-MATTSON FT—IR spectrophotometer, (KBr) 2930?cm-1 (O—H), 1249?cm-1 (N—O). These values are consistent with those reported in the literature (Bueno, 1990).

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	0.0000	0.05806 (17)	0.2500	0.0632 (6)
N1	0.0000	0.17689 (19)	0.2500	0.0438 (6)
C1	−0.07221 (17)	0.23638 (18)	0.1025 (2)	0.0478 (5)
H1	−0.1210	0.1945	0.0006	0.057*
C2	−0.07418 (18)	0.35833 (18)	0.1018 (3)	0.0486 (5)
H2	−0.1264	0.3984	−0.0003	0.058*
C3	0.0000	0.4234 (2)	0.2500	0.0467 (7)
C4	0.0000	0.5569 (3)	0.2500	0.0734 (10)
H41	−0.0355	0.5854	0.1337	0.088*	0.50
H42	0.0812	0.5854	0.3184	0.088*	0.50
H43	−0.0458	0.5854	0.2979	0.088*	0.50
O2	0.82209 (15)	0.93184 (14)	0.23888 (19)	0.0644 (5)
H2A	0.8762	0.9803	0.2367	0.084 (9)*
C5	0.78890 (17)	0.84215 (17)	0.1197 (2)	0.0438 (5)
C6	0.82546 (18)	0.83686 (18)	0.0020 (2)	0.0475 (5)
H6	0.8766	0.8950	0.0030	0.057*
C7	0.78611 (18)	0.74539 (19)	−0.1167 (2)	0.0483 (5)
H7	0.8106	0.7428	−0.1960	0.058*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0624 (14)	0.0373 (11)	0.0854 (16)	0.000	0.0356 (12)	0.000
N1	0.0410 (12)	0.0410 (13)	0.0511 (13)	0.000	0.0252 (11)	0.000
C1	0.0426 (10)	0.0549 (13)	0.0410 (10)	−0.0016 (10)	0.0184 (9)	−0.0038 (9)
C2	0.0452 (11)	0.0520 (13)	0.0436 (11)	0.0064 (9)	0.0198 (9)	0.0076 (9)
C3	0.0448 (16)	0.0441 (16)	0.0542 (17)	0.000	0.0280 (14)	0.000
C4	0.076 (2)	0.0467 (19)	0.084 (3)	0.000	0.032 (2)	0.000
O2	0.0804 (11)	0.0589 (10)	0.0639 (10)	−0.0185 (9)	0.0447 (9)	−0.0214 (8)
C5	0.0459 (10)	0.0441 (11)	0.0403 (10)	0.0003 (9)	0.0218 (9)	−0.0015 (8)
C6	0.0502 (11)	0.0483 (11)	0.0480 (11)	−0.0110 (9)	0.0285 (9)	0.0002 (9)
C7	0.0507 (11)	0.0578 (12)	0.0452 (10)	−0.0063 (10)	0.0312 (9)	−0.0025 (9)

Geometric parameters (Å, º)

O1—N1	1.332 (3)	C4—H43	0.9600
N1—C1	1.344 (2)	O2—C5	1.371 (2)
C1—C2	1.367 (3)	O2—H2A	0.8990
C1—H1	0.9300	C5—C6	1.382 (3)
C2—C3	1.384 (2)	C6—C7	1.378 (3)
C2—H2	0.9300	C6—H6	0.9300
C3—C4	1.497 (4)	C7—C5^i	1.376 (3)
C4—H41	0.9600	C7—H7	0.9300
C4—H42	0.9600
O1—N1—C1^ii	119.75 (12)	C3—C4—H43	109.5
O1—N1—C1	119.75 (12)	H41—C4—H43	109.5
N1—C1—C2	120.2 (2)	H42—C4—H43	109.5
N1—C1—H1	119.9	C5—O2—H2A	110.61
C2—C1—H1	119.9	O2—C5—C7^i	117.70 (17)
C1—C2—C3	121.3 (2)	O2—C5—C6	123.29 (18)
C1—C2—H2	119.3	C7^i—C5—C6	119.00 (18)
C3—C2—H2	119.3	C7—C6—C5	120.00 (18)
C2—C3—C2^ii	116.4 (3)	C7—C6—H6	120.0
C2—C3—C4	121.78 (13)	C5—C6—H6	120.0
C2^ii—C3—C4	121.78 (13)	C5^i—C7—C6	121.01 (17)
C3—C4—H41	109.5	C5^i—C7—H7	119.5
C3—C4—H42	109.5	C6—C7—H7	119.5
H41—C4—H42	109.5
O1—N1—C1—C2	178.99 (14)	C1—C2—C3—C4	178.99 (14)
C1^ii—N1—C1—C2	−1.01 (14)	O2—C5—C6—C7	−178.47 (18)
N1—C1—C2—C3	2.0 (3)	C7^i—C5—C6—C7	0.5 (3)
C1—C2—C3—C2^ii	−1.01 (14)	C5—C6—C7—C5^i	−0.5 (3)

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