2-Iodo­benzaldehyde

In the title compound, C₇H₅IO, the intra­molecular bond lengths and angles are normal. Non-crystallographic C_s symmetry is broken by a 10.4 (2)° inter­planar angle between the formyl group and the aromatic plane. The shortest inter­molecular contact [I...O = 3.124 (3) Å; 0.38 Å shorter than the sum of the respective van der Waals radii] reveals the presence of a dispersive I...O attraction.

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.025
• wR factor = 0.049
• Data-to-parameter ratio = 19.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT431_ALERT_2_B Short Inter HL..A Contact  I      ..  O       ..       3.12 Ang.

Author Response: discussed as an attractive dispersive interaction between I and O.

Alert level C
PLAT194_ALERT_1_C Missing _cell_measurement_reflns_used datum ....          ?
PLAT850_ALERT_2_C Check Flack Parameter Exact Value 0.00 and su ..       0.05

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           27.53
           From the CIF: _reflns_number_total               1614
           Count of symmetry unique reflns          979
           Completeness (_total/calc)            164.86%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       635
           Fraction of Friedel pairs measured     0.649
           Are heavy atom types Z>Si present        yes

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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

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S1. Comment

The title compound (I) was prepared as an intermediate in the synthesis of ortho-iodomandelic acid.

In the molecule, the formyl group is almost coplanar to the aromatic system but is tilted by about 10° with respect to the aromatic ring. This value is markedly smaller than the same angle in the sterically overloaded di-iodo derivative described by Matos Beja et al. (2002). The H atom of the formyl group is oriented to the I atom (Fig. 1). Bond lengths and angles are normal (Matos Beja et al., 2002).

In terms of van-der-Waals radii, the shortest intermolecular contact stems from an obviously dispersive attraction between iodine and oxygen atoms (0.38 Å less than the sum of vdW radii). Other intermolecular contacts are outside the van-der-Waals surface of the individual atoms.

Related literature

For the synthesis of the title compound, see Angyal et al. (1949). For the crystal structure of a related compound in whi iodine atoms are present in close proximity to the formyl group, see Matos Beja et al. (2002).

S2. Experimental

The title compound was obtained as an intermediate in the synthesis of ortho-iodomandelic acid according to a published procedure (Angyal et al., 1949) upon decomposition of the hexamine salt of 2-iodobenzyl bromide under aqueous acidic conditions. Crystals suitable for X-ray analysis were obtained by recrystallization of the compound from boiling n-pentane.

S3. Refinement

All H atoms were located in a difference map and refined as riding on their parent atoms. One common isotropic displacement parameter for all H atoms was refined to 0.048 (6).

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of (I), with atom labels and anisotropic displacement ellipsoids drawn at the 50% probability level for non-H atoms.
	Fig. 2. The packing of (I), viewed along [-1 0 0]. Dotted green lines denote short iodine···oxygen contacts.

2-Iodobenzaldehyde

Crystal data

C7H5IO	F(000) = 432
Mr = 232.01	Dx = 2.193 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	θ = 3.8–27.5°
a = 4.1213 (5) Å	µ = 4.47 mm^−1
b = 11.4948 (12) Å	T = 200 K
c = 14.8310 (14) Å	Platelet, colourless
V = 702.60 (13) Å^3	0.29 × 0.11 × 0.04 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1614 independent reflections
Radiation source: fine-focus sealed tube	1486 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
ω–scans	θmax = 27.5°, θmin = 3.8°
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	h = −5→2
Tmin = 0.597, Tmax = 0.866	k = −14→14
4122 measured reflections	l = −19→18

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.025	H-atom parameters constrained
wR(F^2) = 0.049	w = 1/[σ^2(Fo^2) + (0.0187P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.98	(Δ/σ)max < 0.001
1614 reflections	Δρmax = 0.39 e Å^−3
83 parameters	Δρmin = −0.87 e Å^−3
0 restraints	Absolute structure: Flack (1983); 635 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.003 (45)

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

	x	y	z	Uiso*/Ueq
I	−0.20356 (6)	−0.15824 (2)	0.674261 (19)	0.02777 (8)
O	0.4098 (8)	0.1724 (3)	0.6713 (2)	0.0490 (9)
C1	0.2202 (11)	0.0923 (3)	0.6618 (3)	0.0324 (9)
H1	0.1275	0.0586	0.7143	0.048 (6)*
C2	0.1259 (10)	0.0447 (4)	0.5732 (3)	0.0241 (9)
C3	−0.0529 (10)	−0.0579 (3)	0.5630 (3)	0.0241 (9)
C4	−0.1329 (10)	−0.0984 (4)	0.4781 (3)	0.0295 (10)
H4	−0.2512	−0.1688	0.4717	0.048 (6)*
C5	−0.0413 (11)	−0.0367 (4)	0.4026 (3)	0.0353 (11)
H5	−0.0973	−0.0648	0.3445	0.048 (6)*
C6	0.1309 (11)	0.0655 (4)	0.4108 (3)	0.0328 (11)
H6	0.1890	0.1086	0.3586	0.048 (6)*
C7	0.2193 (11)	0.1051 (3)	0.4958 (3)	0.0298 (9)
H7	0.3446	0.1741	0.5014	0.048 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I	0.02795 (13)	0.02990 (12)	0.02547 (12)	−0.00281 (11)	0.00231 (11)	0.00323 (13)
O	0.064 (2)	0.0406 (18)	0.0419 (19)	−0.0213 (16)	0.0052 (19)	−0.0156 (19)
C1	0.041 (2)	0.0304 (19)	0.025 (2)	−0.001 (2)	0.001 (2)	−0.0025 (18)
C2	0.027 (2)	0.0211 (18)	0.024 (2)	0.0036 (17)	0.0032 (17)	−0.0006 (16)
C3	0.024 (2)	0.026 (2)	0.022 (2)	0.0040 (17)	−0.0006 (18)	0.0033 (18)
C4	0.030 (2)	0.034 (2)	0.025 (2)	0.0001 (19)	−0.0025 (18)	−0.002 (2)
C5	0.037 (3)	0.049 (3)	0.020 (2)	0.014 (2)	−0.0025 (19)	−0.004 (2)
C6	0.038 (3)	0.036 (2)	0.025 (2)	0.011 (2)	0.0051 (19)	0.012 (2)
C7	0.033 (2)	0.0251 (17)	0.031 (2)	0.005 (2)	0.006 (2)	−0.0002 (18)

Geometric parameters (Å, º)

I—C3	2.108 (4)	C4—C5	1.377 (6)
O—C1	1.215 (5)	C4—H4	0.9500
C1—C2	1.476 (6)	C5—C6	1.377 (7)
C1—H1	0.9500	C5—H5	0.9500
C2—C7	1.395 (6)	C6—C7	1.389 (6)
C2—C3	1.398 (6)	C6—H6	0.9500
C3—C4	1.382 (6)	C7—H7	0.9500
I···O^i	3.124 (3)
O—C1—C2	123.6 (4)	C3—C4—H4	120.0
O—C1—H1	118.2	C6—C5—C4	120.6 (4)
C2—C1—H1	118.2	C6—C5—H5	119.7
C7—C2—C3	118.4 (4)	C4—C5—H5	119.7
C7—C2—C1	118.3 (4)	C5—C6—C7	119.6 (4)
C3—C2—C1	123.2 (4)	C5—C6—H6	120.2
C4—C3—C2	120.5 (4)	C7—C6—H6	120.2
C4—C3—I	117.3 (3)	C6—C7—C2	120.7 (4)
C2—C3—I	122.1 (3)	C6—C7—H7	119.7
C5—C4—C3	120.1 (4)	C2—C7—H7	119.7
C5—C4—H4	120.0
O—C1—C2—C7	−10.1 (6)	I—C3—C4—C5	180.0 (3)
O—C1—C2—C3	170.0 (4)	C3—C4—C5—C6	0.1 (6)
C7—C2—C3—C4	0.4 (6)	C4—C5—C6—C7	1.5 (6)
C1—C2—C3—C4	−179.8 (4)	C5—C6—C7—C2	−2.2 (7)
C7—C2—C3—I	179.2 (3)	C3—C2—C7—C6	1.3 (6)
C1—C2—C3—I	−0.9 (6)	C1—C2—C7—C6	−178.6 (4)
C2—C3—C4—C5	−1.1 (6)

Symmetry code: (i) −x, y−1/2, −z+3/2.