Redetermination of 3-deaza-uracil.

The crystal structure of the title compound, 4-hydr-oxy-2-pyridone, C(5)H(5)NO(2), which has been the subject of several determinations using X-rays and neutron diffraction, was first reported by Low & Wilson [Acta Cryst. (1983). C39, 1688-1690]. It has been redetermined, providing a significant increase in the precision of the derived geometric parameters. The asymmetric unit comprises a planar 4-enol tautomer having some degree of delocalization of π-electron density through the mol-ecule. In the crystal structure, the mol-ecules are connected into chains by two strong O-H⋯O and N-H⋯O hydrogen bonds between the OH and NH groups and the carbonyl O atom.

Related literature

For previous structure determinations, see: Low & Wilson (1983 ▶); Wilson et al. (1992 ▶); Wilson (1994 ▶, 2001 ▶). For related literature, see: Stewart & Jensen (1967 ▶): Robins et al. (1969 ▶); Schwalbe & Saenger (1973 ▶). For a general approach to the use of multiple-hydrogen-bonding DNA/RNA nucleobases as potential supra­molecular reagents, see: Portalone et al. (1999 ▶); Portalone & Colapietro (2004 ▶, 2007 ▶ and references therein). For high-order refinement, see: Hirshfeld (1992 ▶). For the computation of ring patterns formed by hydrogen bonds in crystal structures, see: Etter et al. (1990 ▶); Bernstein et al. (1995 ▶); Motherwell et al. (1999 ▶).

Experimental

Crystal data

C5H5NO2

M = 111.10

Orthorhombic,

a = 5.3393 (1) Å

b = 8.6454 (1) Å

c = 11.2652 (2) Å

V = 520.01 (1) Å3

Z = 4

Mo Kα radiation

μ = 0.11 mm−1

T = 298 (2) K

0.20 × 0.15 × 0.15 mm

Data collection

Oxford Diffraction Xcalibur S CCD diffractometer

Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006 ▶) T min = 0.924, T max = 0.983

77963 measured reflections

1085 independent reflections

1043 reflections with I > 2σ(I)

R int = 0.025

Refinement

R[F 2 > 2σ(F 2)] = 0.038

wR(F 2) = 0.112

S = 1.10

1085 reflections

93 parameters

All H-atom parameters refined

Δρmax = 0.22 e Å−3

Δρmin = −0.13 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: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808014578/kp2171sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808014578/kp2171Isup2.hkl

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

C5H5NO2	Dx = 1.419 Mg m−3
Mr = 111.10	Melting point: 477 K
Orthorhombic, P212121	Mo Kα radiation λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 43477 reflections
a = 5.3393 (1) Å	θ = 2.9–32.3º
b = 8.6454 (1) Å	µ = 0.11 mm−1
c = 11.2652 (2) Å	T = 298 (2) K
V = 520.006 (14) Å3	Tablets, colourless
Z = 4	0.20 × 0.15 × 0.15 mm
F000 = 232

Oxford Diffraction Xcalibur S CCD diffractometer	1085 independent reflections
Radiation source: Enhance (Mo) X-ray source	1043 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.025
Detector resolution: 16.0696 pixels mm-1	θmax = 32.4º
T = 298(2) K	θmin = 3.0º
ω and φ scans	h = −8→7
Absorption correction: multi-scan(CrysAlis RED; Oxford Diffraction, 2006)	k = −13→12
Tmin = 0.924, Tmax = 0.983	l = −16→16
77963 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)] = 0.038	All H-atom parameters refined
wR(F2) = 0.112	w = 1/[σ2(Fo2) + (0.0765P)2 + 0.037P] where P = (Fo2 + 2Fc2)/3
S = 1.10	(Δ/σ)max < 0.001
1085 reflections	Δρmax = 0.22 e Å−3
93 parameters	Δρmin = −0.13 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Experimental. (CrysAlis RED; Oxford Diffraction Ltd., Version 1.171.31.7 (release 18-10-2006 CrysAlis171 .NET) (compiled Oct 18 2006,16:28:17) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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
O1	0.5630 (2)	0.19169 (12)	0.88298 (9)	0.0418 (3)
O2	0.8080 (2)	−0.31430 (11)	0.76490 (11)	0.0423 (3)
H2	0.667 (4)	−0.302 (3)	0.711 (2)	0.056 (6)*
N1	0.9062 (2)	0.07483 (13)	0.96127 (9)	0.0329 (2)
H1	0.935 (5)	0.163 (3)	1.000 (2)	0.052 (6)*
C2	0.7058 (2)	0.07410 (13)	0.88575 (10)	0.0289 (2)
C3	0.6712 (2)	−0.06036 (13)	0.81646 (10)	0.0287 (2)
H3	0.523 (4)	−0.072 (2)	0.763 (2)	0.056 (6)*
C4	0.8348 (2)	−0.18253 (14)	0.82563 (11)	0.0299 (3)
C5	1.0428 (3)	−0.17405 (17)	0.90371 (13)	0.0363 (3)
H5	1.161 (4)	−0.263 (3)	0.9032 (17)	0.054 (6)*
C6	1.0714 (3)	−0.04424 (17)	0.96924 (12)	0.0362 (3)
H6	1.212 (4)	−0.021 (2)	1.0225 (18)	0.045 (5)*

	U11	U22	U33	U12	U13	U23
O1	0.0522 (6)	0.0310 (4)	0.0421 (5)	0.0126 (5)	−0.0071 (5)	−0.0089 (4)
O2	0.0473 (6)	0.0304 (4)	0.0493 (5)	0.0056 (5)	−0.0048 (5)	−0.0116 (4)
N1	0.0378 (5)	0.0301 (5)	0.0308 (5)	−0.0046 (4)	−0.0035 (4)	−0.0040 (4)
C2	0.0330 (5)	0.0261 (5)	0.0277 (5)	0.0007 (5)	0.0004 (4)	−0.0020 (4)
C3	0.0291 (5)	0.0270 (5)	0.0301 (5)	0.0014 (4)	−0.0025 (4)	−0.0041 (4)
C4	0.0307 (6)	0.0269 (5)	0.0321 (5)	0.0003 (5)	0.0013 (4)	−0.0020 (4)
C5	0.0306 (6)	0.0352 (6)	0.0432 (6)	0.0044 (5)	−0.0041 (5)	0.0007 (5)
C6	0.0318 (6)	0.0400 (6)	0.0369 (6)	−0.0037 (5)	−0.0070 (5)	0.0015 (5)

O1—C2	1.2713 (15)	C3—C4	1.3746 (16)
O2—C4	1.3366 (15)	C3—H3	1.00 (2)
O2—H2	0.97 (2)	C4—C5	1.4187 (19)
N1—C6	1.3587 (17)	C5—C6	1.3519 (19)
N1—C2	1.3668 (17)	C5—H5	1.00 (2)
N1—H1	0.89 (2)	C6—H6	0.98 (2)
C2—C3	1.4123 (15)
C4—O2—H2	107.8 (14)	O2—C4—C3	123.25 (11)
C6—N1—C2	123.08 (10)	O2—C4—C5	116.44 (11)
C6—N1—H1	120.3 (16)	C3—C4—C5	120.30 (11)
C2—N1—H1	116.2 (16)	C6—C5—C4	118.02 (12)
O1—C2—N1	118.75 (10)	C6—C5—H5	125.0 (13)
O1—C2—C3	124.48 (12)	C4—C5—H5	117.0 (13)
N1—C2—C3	116.76 (11)	C5—C6—N1	121.30 (12)
C4—C3—C2	120.51 (11)	C5—C6—H6	126.0 (12)
C4—C3—H3	118.3 (12)	N1—C6—H6	112.6 (12)
C2—C3—H3	121.1 (12)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1i	0.97 (2)	1.62 (2)	2.5886 (16)	171.3 (16)
N1—H1···O1ii	0.89 (2)	1.94 (2)	2.8024 (14)	160.6 (15)

	3Deazur						Uracil
	This worka	This workb	LTNDc	PNDd	X-Ne	XRDf	XRDg
N1-C2	1.3668 (17)	1.3696 (13)	1.362 (3)	1.332 (6)	1.362 (6)	1.360 (4)	1.371 (3)
N1-C6	1.3587 (17)	1.3577 (15)	1.355 (3)	1.356 (6)	1.367 (7)	1.359 (4)	1.358 (2)
C2-C3	1.4123 (15)	1.4141 (11)	1.414 (3)	1.409 (7)	1.409 (6)	1.412 (4)	—
C5-C6	1.3519 (19)	1.3587 (15)	1.360 (4)	1.350 (8)	1.355 (7)	1.348 (4)	1.340 (2)
C3-C4	1.3746 (16)	1.3860 (12)	1.385 (4)	1.381 (7)	1.375 (7)	1.381 (4)	—
C4-C5	1.4187 (19)	1.4183 (15)	1.411 (4)	1.417 (8)	1.400 (7)	1.411 (4)	1.430 (3)
C2-O1	1.2713 (15)	1.2735 (12)	1.266 (4)	1.268 (7)	1.266 (6)	1.262 (4)	1.215 (2)
C4-O2	1.3366 (15)	1.3342 (11)	1.322 (4)	1.345 (8)	1.346 (5)	1.319 (3)	1.245 (2)
O2···O1i	2.5886 (16)	2.5843 (16)	2.563 (4)	2.575 (11)	2.581 (6)	2.550 (4)	—
N1···O1ii	2.8024 (14)	2.7998 (12)	2.785 (3)	2.776 (8)	2.796 (5)	2.807 (4)	2.861 (2)
O2-H2···O1i	171.3 (16)	172.8 (9)	177.7 (7)	174.6 (13)	166 (4)	—	—
N1-H1···O1ii	160.6 (15)	164.7 (8)	165.5 (6)	164.0 (10)	158 (4)	156	171 (1)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1i	0.97 (2)	1.62 (2)	2.5886 (16)	171.3 (16)
N1—H1⋯O1ii	0.89 (2)	1.94 (2)	2.8024 (14)	160.6 (15)

Symmetry codes: (i) ; (ii) .