2-Hydr­oxy-7-iodo­cyclo­hepta-2,4,6-trien-1-one

The title compound, also known as 7-iodo­tropolone, C₇H₅IO₂, exists in the crystalline state as the 2-hydr­oxy-7-iodo­cyclo­hepta-2,4,6-trien-1-one tautomer and not as 2-hydr­oxy-3-iodo­cyclo­hepta-2,4,6-trien-1-one. There is a bifurcated O—H...O bond with two acceptor O atoms. One of these acceptors is involved in an intra­molecular hydrogen bond, and the other in an inter­molecular hydrogen bond. There is also a C—H...O inter­action in the structure. In addition, there is a C—O...π-cyclo­hepta­triene inter­action.

Key indicators

• Single-crystal X-ray study
• T = 153 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.019
• wR factor = 0.045
• Data-to-parameter ratio = 17.8

checkCIF/PLATON results

No syntax errors found



Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.47
           From the CIF: _reflns_number_total               1669
           Count of symmetry unique reflns         1027
           Completeness (_total/calc)            162.51%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       642
           Fraction of Friedel pairs measured     0.625
           Are heavy atom types Z>Si present        yes

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

Computing details

Data collection: CrystalClear (Rigaku, 1999); cell refinement: CrystalClear; data reduction: CrystalStructure (Rigaku/MSC, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and Mercury (Version 1.3; Bruno et al., 2002); software used to prepare material for publication: CrystalStructure.

2-Hydroxy-7-iodocyclohepta-2,4,6-trien-1-one

Crystal data

C7H5IO2	F(000) = 464.00
Mr = 248.02	Dx = 2.255 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2368 reflections
a = 4.3755 (11) Å	θ = 3.0–27.5°
b = 6.2034 (15) Å	µ = 4.32 mm^−1
c = 26.912 (6) Å	T = 153 K
V = 730.5 (3) Å^3	Prism, colourless
Z = 4	0.14 × 0.13 × 0.07 mm

Data collection

Rigaku Saturn diffractometer	1669 independent reflections
Radiation source: fine-focus sealed tube	1632 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
Detector resolution: 7.31 pixels mm^-1	θmax = 27.5°
ω scans	h = −5→5
Absorption correction: multi-scan (REQAB; Jacobson, 1998)	k = −7→8
Tmin = 0.564, Tmax = 0.739	l = −34→27
5062 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.019	H-atom parameters constrained
wR(F^2) = 0.045	w = 1/[σ^2(Fo^2) + (0.0154P)^2 + 0.6866P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.003
1669 reflections	Δρmax = 0.50 e Å^−3
94 parameters	Δρmin = −0.64 e Å^−3
0 restraints	Extinction correction: SHELXL97
14 constraints	Extinction coefficient: 0.0025 (5)
Primary atom site location: structure-invariant direct methods	Absolute structure: 643 Friedel Pairs (Flack, 1983)
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.02 (3)

Special details

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY

Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	Uiso*/Ueq
I1	0.58499 (5)	0.19582 (4)	0.707083 (7)	0.02574 (7)
O1	0.4309 (6)	0.2011 (3)	0.59640 (8)	0.0295 (5)
O2	0.5665 (6)	0.3920 (3)	0.51660 (8)	0.0249 (4)
C1	0.6120 (8)	0.3538 (4)	0.60278 (11)	0.0198 (6)
C2	0.6935 (7)	0.4747 (5)	0.55806 (12)	0.0203 (6)
C3	0.8742 (8)	0.6534 (4)	0.55192 (13)	0.0249 (7)
C4	1.0313 (7)	0.7752 (5)	0.58772 (14)	0.0284 (7)
C5	1.0492 (8)	0.7427 (4)	0.63746 (13)	0.0275 (7)
C6	0.9137 (9)	0.5754 (5)	0.66585 (11)	0.0242 (6)
C7	0.7293 (7)	0.4098 (5)	0.65102 (11)	0.0193 (5)
H1	0.4550	0.2868	0.5242	0.037*
H2	0.8963	0.7017	0.5186	0.030*
H3	1.1396	0.8968	0.5754	0.034*
H4	1.1672	0.8445	0.6555	0.033*
H5	0.9578	0.5791	0.7004	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.02574 (11)	0.03474 (12)	0.01674 (11)	−0.00367 (10)	−0.00006 (9)	0.00254 (8)
O1	0.0413 (13)	0.0274 (11)	0.0200 (10)	−0.0144 (15)	−0.0023 (10)	0.0018 (9)
O2	0.0289 (12)	0.0253 (10)	0.0205 (10)	−0.0057 (11)	−0.0011 (10)	0.0008 (8)
C1	0.0196 (14)	0.0194 (13)	0.0203 (14)	−0.0007 (12)	−0.0004 (12)	−0.0003 (10)
C2	0.0197 (15)	0.0202 (14)	0.0210 (15)	0.0012 (12)	0.0006 (11)	−0.0016 (11)
C3	0.0216 (16)	0.0224 (15)	0.0307 (16)	−0.0059 (12)	−0.0002 (13)	0.0075 (12)
C4	0.0245 (16)	0.0210 (15)	0.0396 (18)	−0.0055 (13)	0.0019 (13)	0.0028 (14)
C5	0.0239 (16)	0.0217 (15)	0.0368 (18)	−0.0053 (12)	−0.0015 (14)	−0.0085 (12)
C6	0.0236 (14)	0.0284 (15)	0.0206 (14)	−0.0030 (16)	−0.0009 (14)	−0.0064 (11)
C7	0.0157 (14)	0.0252 (14)	0.0169 (14)	−0.0005 (13)	0.0024 (12)	0.0006 (11)

Geometric parameters (Å, º)

I1—C7	2.107 (3)	C5—C6	1.418 (4)
O1—C1	1.247 (4)	C6—C7	1.366 (4)
O2—C2	1.348 (3)	O2—H1	0.840
C1—C2	1.462 (4)	C3—H2	0.950
C1—C7	1.439 (4)	C4—H3	0.950
C2—C3	1.371 (4)	C5—H4	0.950
C3—C4	1.404 (4)	C6—H5	0.950
C4—C5	1.356 (5)
O1···O2^i	3.482 (3)	H2···C3^v	3.103
O1···C4^ii	3.177 (4)	H2···C3^vii	2.964
O1···C5^ii	3.478 (4)	H2···C4^v	3.280
O2···O1^iii	3.482 (3)	H2···H2^v	2.480
O2···O2^i	2.948 (3)	H2···H2^vii	2.480
O2···O2^iii	2.948 (3)	H2···H3^v	2.836
O2···C2^i	3.446 (3)	H2···H1	3.221
O2···C3^iv	3.565 (4)	H2···H1^vi	3.553
O2···C3^v	3.473 (3)	H2···H1^iii	3.252
O2···C4^v	3.488 (4)	H2···H1^vii	3.385
C1···C5^iv	3.571 (4)	H3···O1^viii	2.347
C2···O2^iii	3.446 (3)	H3···O2^vii	2.820
C2···C4^iv	3.537 (4)	H3···C1^viii	3.585
C3···O2^vi	3.565 (4)	H3···C2^vi	3.598
C3···O2^vii	3.473 (3)	H3···C3^vii	3.591
C4···O1^viii	3.177 (4)	H3···H2^vii	2.836
C4···O2^vii	3.488 (4)	H3···H1^viii	3.108
C4···C2^vi	3.537 (4)	H3···H1^vii	3.420
C5···O1^viii	3.478 (4)	H4···O1^viii	2.959
C5···C1^vi	3.571 (4)	H5···I1^xi	3.516
I1···H4^ii	3.165	H5···I1^xii	3.275
I1···H5^ix	3.516	H1···O1	2.017
I1···H5^x	3.275	H1···O2	0.840
O1···H3^ii	2.347	H1···O2^i	2.308
O1···H4^ii	2.959	H1···O2^iii	3.098
O1···H1	2.017	H1···C1	2.262
O2···H2^iv	3.506	H1···C2	1.810
O2···H2^v	2.794	H1···C2^i	2.974
O2···H3^v	2.820	H1···C3^iv	3.491
O2···H1^i	3.098	H1···C3	3.015
O2···H1^iii	2.308	H1···C3^i	3.432
C1···H3^ii	3.585	H1···H2^iv	3.553
C1···H1	2.262	H1···H2	3.221
C2···H2^v	3.159	H1···H2^i	3.252
C2···H3^iv	3.598	H1···H2^v	3.385
C2···H1	1.810	H1···H3^ii	3.108
C2···H1^iii	2.974	H1···H3^v	3.420
C3···H2^v	2.964	H1···H1^i	2.587
C3···H2^vii	3.103	H1···H1^iii	2.587
C3···H3^v	3.591	O2···O2^i	2.948 (3)
C3···H1	3.015	C4···O1^viii	3.177 (4)
C3···H1^vi	3.491	H1···O2^i	2.310
C3···H1^iii	3.432	H3···O1^viii	2.350
C4···H2^vii	3.280	I1···I1^xi	3.9382 (10)
H2···O2^vi	3.506	I1···I1^ix	3.9382 (10)
H2···O2^vii	2.794	C5···I1^viii	4.112 (3)
H2···C2^vii	3.159	H4···I1^viii	3.165
O1—C1—C2	115.6 (2)	I1—C7—C6	116.2 (2)
O1—C1—C7	122.3 (2)	C1—C7—C6	131.0 (2)
C2—C1—C7	122.1 (2)	C2—O2—H1	109.5
O2—C2—C1	112.7 (2)	C2—C3—H2	115.3
O2—C2—C3	116.5 (2)	C4—C3—H2	115.3
C1—C2—C3	130.9 (3)	C3—C4—H3	115.6
C2—C3—C4	129.4 (3)	C5—C4—H3	115.6
C3—C4—C5	128.7 (3)	C4—C5—H4	116.0
C4—C5—C6	128.1 (3)	C6—C5—H4	116.0
C5—C6—C7	129.8 (2)	C5—C6—H5	115.1
I1—C7—C1	112.8 (2)	C7—C6—H5	115.1
O1—C1—C2—O2	−2.9 (4)	O2—C2—C3—C4	179.0 (3)
O1—C1—C2—C3	177.3 (3)	C1—C2—C3—C4	−1.2 (6)
O1—C1—C7—I1	3.7 (4)	C2—C3—C4—C5	1.8 (6)
O1—C1—C7—C6	−176.1 (3)	C3—C4—C5—C6	0.3 (6)
C2—C1—C7—I1	−177.3 (2)	C4—C5—C6—C7	−1.4 (6)
C2—C1—C7—C6	2.8 (5)	C5—C6—C7—I1	179.4 (3)
C7—C1—C2—O2	178.1 (2)	C5—C6—C7—C1	−0.8 (6)
C7—C1—C2—C3	−1.7 (5)

Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x−1, y−1, z; (iii) x+1/2, −y+1/2, −z+1; (iv) x−1, y, z; (v) x−1/2, −y+3/2, −z+1; (vi) x+1, y, z; (vii) x+1/2, −y+3/2, −z+1; (viii) x+1, y+1, z; (ix) −x+1, y−1/2, −z+3/2; (x) −x+2, y−1/2, −z+3/2; (xi) −x+1, y+1/2, −z+3/2; (xii) −x+2, y+1/2, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1···O1	0.84	2.02	2.523 (3)	118
O2—H1···O2^i	0.84	2.31	2.948 (3)	133
C4—H3···O1^viii	0.95	2.35	3.177 (4)	146

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