Dimethyl 4-iodo­pyridine-2,6-dicarboxyl­ate

Two symmetry-independent but geometrically similar, essentially planar mol­ecules of the title compound, C₉H₈INO₄, are linked via C—I...O=C inter­actions [I...O = 2.981 (6) and 3.006 (5) Å] into infinite chains running along the b axis. The independent mol­ecules alternate within the chain, so that only one independent chain is formed in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.011 Å
• R factor = 0.050
• wR factor = 0.096
• Data-to-parameter ratio = 13.5

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT431_ALERT_2_A Short Inter HL..A Contact  I1     ..  O34     ..       2.98 Ang.

Author Response: We agree that there are two unusally short intermolecular contacts between I1..O34 and I2..O13 but these are the minimized structures. Since the reaction was a bromo - iodo exchange, we investigated the possibility of the Bromo derivative by both NMR and mass spectrometry and experimental evidence supports the iodo derivative. The protons ortho to the halogen shift upon coversion to the iodo-derivative and the mass spectrum (electrospray ionization-poisitve ion mode) showed only two peaks at 344 (M + Na+) and 360 (M + K+). No molecular ion was observed in either postive or negative mode. Also, no peaks that could be attributed to the Br-derivative were observed.

Alert level B
PLAT431_ALERT_2_B Short Inter HL..A Contact  I2     ..  O13     ..       3.01 Ang.

Author Response: We agree that there are two unusally short intermolecular contacts between I1..O34 and I2..O13 but these are the minimized structures. Since the reaction was a bromo - iodo exchange, we investigated the possibility of the Bromo derivative by both NMR and mass spectrometry and experimental evidence supports the iodo derivative. The protons ortho to the halogen shift upon coversion to the iodo-derivative and the mass spectrum (electrospray ionization-poisitve ion mode) showed only two peaks at 344 (M + Na+) and 360 (M + K+). No molecular ion was observed in either postive or negative mode. Also, no peaks that could be attributed to the Br-derivative were observed.

Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.38
PLAT342_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...         11

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 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

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Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 2005); software used to prepare material for publication: PLATON (Spek, 2003).

dimethyl 4-iodopyridine-2,6-dicarboxylate

Crystal data

C9H8INO4	Z = 4
Mr = 321.07	F(000) = 616
Triclinic, P1	Dx = 2.024 Mg m^−3
Hall symbol: -P 1	Melting point: 173 K
a = 4.2120 (12) Å	Mo Kα radiation, λ = 0.71073 Å
b = 13.359 (2) Å	Cell parameters from 3723 reflections
c = 19.236 (2) Å	θ = 1.6–25.3°
α = 99.936 (5)°	µ = 3.03 mm^−1
β = 94.326 (6)°	T = 173 K
γ = 96.790 (6)°	Needle, yellow
V = 1053.6 (4) Å^3	0.08 × 0.04 × 0.02 mm

Data collection

Nonius KappaCCD diffractometer	3723 independent reflections
Radiation source: fine-focus sealed tube	2296 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ω and φ scans	θmax = 25.3°, θmin = 1.6°
Absorption correction: multi-scan (SORTAV; Blessing, 1997)	h = −5→5
Tmin = 0.793, Tmax = 0.942	k = −14→15
5334 measured reflections	l = −22→22

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0255P)^2 + 0.5615P] where P = (Fo^2 + 2Fc^2)/3
3723 reflections	(Δ/σ)max = 0.001
275 parameters	Δρmax = 1.08 e Å^−3
0 restraints	Δρmin = −0.78 e Å^−3

Special details

Experimental. C₉H₈INO₄: ¹H NMR (300 MHz, CDCl₃) δ 8.67 (s, 2H), 4.03 (s, 6H).

C₉H₈BrNO₄: ¹H NMR (300 MHz, CDCl₃) δ 8.48 (s, 2H), 4.05 (s, 6H)

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
I1	0.73413 (12)	0.45939 (4)	0.22152 (3)	0.03075 (19)
I2	0.02699 (12)	0.06208 (4)	0.71406 (3)	0.0333 (2)
O8	−0.2442 (13)	0.0395 (4)	0.0700 (3)	0.0400 (16)
O11	−0.1904 (13)	0.2729 (4)	−0.0806 (3)	0.0389 (16)
O13	0.0551 (14)	0.0694 (5)	0.1748 (3)	0.0502 (18)
O14	0.1561 (15)	0.4174 (5)	−0.0580 (3)	0.054 (2)
O28	−0.1482 (12)	0.2288 (4)	0.4081 (3)	0.0365 (15)
O31	0.6008 (12)	0.4504 (4)	0.5677 (3)	0.0321 (14)
O33	−0.4145 (13)	0.0875 (5)	0.4358 (3)	0.0428 (17)
O34	0.8312 (12)	0.4006 (4)	0.6636 (3)	0.0333 (15)
N1	0.0042 (14)	0.2205 (5)	0.0411 (3)	0.0235 (16)
N21	0.2139 (14)	0.2712 (5)	0.5325 (3)	0.0230 (16)
C2	0.1335 (18)	0.3126 (6)	0.0300 (4)	0.026 (2)
C3	0.3483 (17)	0.3824 (7)	0.0778 (4)	0.031 (2)
H3	0.4326	0.4460	0.0650	0.037*
C4	0.4358 (18)	0.3555 (6)	0.1421 (4)	0.027 (2)
C5	0.3105 (17)	0.2621 (7)	0.1552 (4)	0.029 (2)
H5	0.3737	0.2432	0.1997	0.035*
C6	0.0979 (18)	0.1974 (7)	0.1043 (4)	0.026 (2)
C7	−0.031 (2)	0.0956 (7)	0.1207 (5)	0.036 (2)
C9	−0.375 (2)	−0.0599 (7)	0.0838 (4)	0.038 (2)
H9A	−0.5355	−0.0940	0.0448	0.046*
H9B	−0.4762	−0.0507	0.1283	0.046*
H9C	−0.2015	−0.1021	0.0876	0.046*
C10	0.0372 (19)	0.3402 (7)	−0.0409 (4)	0.029 (2)
C12	−0.288 (2)	0.2975 (7)	−0.1486 (4)	0.044 (3)
H12A	−0.4579	0.2444	−0.1739	0.053*
H12B	−0.1031	0.3007	−0.1766	0.053*
H12C	−0.3686	0.3640	−0.1415	0.053*
C22	0.3829 (18)	0.2921 (6)	0.5959 (4)	0.027 (2)
C23	0.3453 (17)	0.2334 (6)	0.6479 (4)	0.025 (2)
H23	0.4792	0.2516	0.6920	0.030*
C24	0.1164 (17)	0.1478 (7)	0.6353 (4)	0.027 (2)
C25	−0.0624 (17)	0.1227 (6)	0.5693 (4)	0.027 (2)
H25	−0.2195	0.0626	0.5596	0.033*
C26	−0.0044 (18)	0.1866 (6)	0.5201 (4)	0.027 (2)
C27	−0.2121 (19)	0.1609 (7)	0.4508 (4)	0.027 (2)
C29	−0.358 (2)	0.2119 (7)	0.3423 (4)	0.043 (3)
H29A	−0.2842	0.2618	0.3133	0.052*
H29B	−0.5782	0.2201	0.3532	0.052*
H29C	−0.3534	0.1423	0.3163	0.052*
C30	0.6308 (19)	0.3850 (6)	0.6136 (4)	0.026 (2)
C32	0.8238 (19)	0.5442 (6)	0.5832 (5)	0.038 (2)
H32A	0.7637	0.5904	0.5515	0.046*
H32B	1.0415	0.5283	0.5759	0.046*
H32C	0.8173	0.5774	0.6325	0.046*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0308 (3)	0.0292 (4)	0.0284 (4)	−0.0050 (3)	−0.0046 (3)	0.0040 (3)
I2	0.0346 (4)	0.0328 (4)	0.0329 (4)	−0.0036 (3)	−0.0010 (3)	0.0145 (3)
O8	0.052 (4)	0.025 (4)	0.039 (4)	−0.017 (3)	−0.013 (3)	0.016 (3)
O11	0.047 (4)	0.031 (4)	0.033 (4)	−0.013 (3)	−0.019 (3)	0.009 (3)
O13	0.074 (4)	0.037 (4)	0.034 (4)	−0.020 (3)	−0.013 (3)	0.019 (3)
O14	0.072 (5)	0.044 (5)	0.039 (4)	−0.025 (4)	−0.018 (3)	0.023 (4)
O28	0.045 (4)	0.031 (4)	0.030 (3)	−0.008 (3)	−0.010 (3)	0.013 (3)
O31	0.038 (3)	0.017 (3)	0.038 (3)	−0.010 (3)	−0.013 (3)	0.011 (3)
O33	0.053 (4)	0.028 (4)	0.041 (4)	−0.020 (3)	−0.007 (3)	0.010 (3)
O34	0.034 (3)	0.029 (4)	0.033 (3)	−0.006 (3)	−0.014 (3)	0.012 (3)
N1	0.024 (4)	0.022 (4)	0.022 (4)	−0.002 (3)	−0.004 (3)	0.001 (3)
N21	0.027 (4)	0.017 (4)	0.025 (4)	0.002 (3)	0.000 (3)	0.007 (3)
C2	0.032 (5)	0.021 (5)	0.025 (5)	−0.002 (4)	−0.004 (4)	0.010 (4)
C3	0.026 (5)	0.034 (6)	0.026 (5)	−0.012 (4)	0.000 (4)	0.001 (4)
C4	0.034 (5)	0.029 (6)	0.016 (4)	0.002 (4)	−0.001 (4)	0.004 (4)
C5	0.026 (5)	0.035 (6)	0.028 (5)	0.004 (4)	−0.002 (4)	0.011 (5)
C6	0.031 (5)	0.030 (6)	0.018 (5)	−0.001 (4)	0.002 (4)	0.008 (4)
C7	0.045 (6)	0.029 (6)	0.031 (5)	0.001 (5)	−0.006 (5)	0.007 (5)
C9	0.045 (5)	0.032 (6)	0.034 (5)	−0.005 (5)	−0.001 (4)	0.006 (5)
C10	0.030 (5)	0.030 (6)	0.021 (5)	−0.005 (4)	−0.002 (4)	−0.001 (4)
C12	0.050 (6)	0.053 (7)	0.027 (5)	−0.015 (5)	−0.015 (5)	0.022 (5)
C22	0.026 (5)	0.021 (5)	0.035 (5)	0.004 (4)	−0.008 (4)	0.011 (4)
C23	0.022 (4)	0.033 (6)	0.021 (4)	0.007 (4)	0.002 (4)	0.008 (4)
C24	0.026 (5)	0.030 (6)	0.026 (5)	0.001 (4)	0.010 (4)	0.005 (4)
C25	0.023 (4)	0.026 (6)	0.034 (5)	−0.002 (4)	0.009 (4)	0.013 (5)
C26	0.029 (5)	0.018 (5)	0.034 (5)	0.000 (4)	0.006 (4)	0.011 (4)
C27	0.039 (5)	0.017 (5)	0.024 (5)	−0.001 (4)	0.005 (4)	0.007 (4)
C29	0.057 (6)	0.043 (7)	0.023 (5)	−0.003 (5)	−0.020 (4)	0.007 (5)
C30	0.029 (5)	0.024 (6)	0.030 (5)	0.013 (4)	0.010 (4)	0.004 (4)
C32	0.049 (6)	0.024 (6)	0.038 (5)	−0.008 (5)	−0.011 (5)	0.013 (5)

Geometric parameters (Å, º)

I1—C4	2.100 (8)	C5—C6	1.379 (11)
I2—C24	2.081 (7)	C5—H5	0.9599
O8—C7	1.333 (10)	C6—C7	1.497 (11)
O8—C9	1.450 (9)	C9—H9A	0.9800
O11—C10	1.327 (9)	C9—H9B	0.9800
O11—C12	1.445 (8)	C9—H9C	0.9800
O13—C7	1.199 (8)	C12—H12A	0.9800
O14—C10	1.201 (9)	C12—H12B	0.9800
O28—C27	1.342 (9)	C12—H12C	0.9800
O28—C29	1.455 (8)	C22—C23	1.380 (10)
O31—C30	1.355 (9)	C22—C30	1.497 (11)
O31—C32	1.446 (9)	C23—C24	1.380 (11)
O33—C27	1.200 (9)	C23—H23	0.9601
O34—C30	1.203 (9)	C24—C25	1.392 (10)
N1—C2	1.343 (9)	C25—C26	1.397 (10)
N1—C6	1.347 (8)	C25—H25	0.9600
N21—C22	1.334 (9)	C26—C27	1.502 (11)
N21—C26	1.344 (9)	C29—H29A	0.9800
C2—C3	1.383 (10)	C29—H29B	0.9800
C2—C10	1.512 (10)	C29—H29C	0.9800
C3—C4	1.381 (9)	C32—H32A	0.9800
C3—H3	0.9599	C32—H32B	0.9800
C4—C5	1.368 (10)	C32—H32C	0.9800
C7—O8—C9	115.5 (6)	O11—C12—H12C	109.5
C10—O11—C12	115.1 (6)	H12A—C12—H12C	109.5
C27—O28—C29	115.3 (6)	H12B—C12—H12C	109.5
C30—O31—C32	115.6 (6)	N21—C22—C23	124.3 (8)
C2—N1—C6	115.4 (7)	N21—C22—C30	119.2 (7)
C22—N21—C26	116.1 (6)	C23—C22—C30	116.5 (7)
N1—C2—C3	125.1 (7)	C24—C23—C22	119.3 (7)
N1—C2—C10	116.7 (7)	C24—C23—H23	120.5
C3—C2—C10	118.2 (7)	C22—C23—H23	120.2
C4—C3—C2	117.4 (8)	C23—C24—C25	118.1 (7)
C4—C3—H3	123.0	C23—C24—I2	121.0 (6)
C2—C3—H3	119.5	C25—C24—I2	120.8 (6)
C5—C4—C3	119.2 (7)	C24—C25—C26	118.2 (8)
C5—C4—I1	119.9 (5)	C24—C25—H25	118.9
C3—C4—I1	120.8 (6)	C26—C25—H25	122.9
C4—C5—C6	119.2 (7)	N21—C26—C25	124.0 (7)
C4—C5—H5	119.1	N21—C26—C27	118.8 (6)
C6—C5—H5	121.7	C25—C26—C27	117.1 (7)
N1—C6—C5	123.6 (7)	O33—C27—O28	124.0 (7)
N1—C6—C7	118.9 (7)	O33—C27—C26	123.0 (7)
C5—C6—C7	117.4 (7)	O28—C27—C26	113.0 (7)
O13—C7—O8	124.6 (8)	O28—C29—H29A	109.5
O13—C7—C6	121.7 (8)	O28—C29—H29B	109.5
O8—C7—C6	113.7 (7)	H29A—C29—H29B	109.5
O8—C9—H9A	109.5	O28—C29—H29C	109.5
O8—C9—H9B	109.5	H29A—C29—H29C	109.5
H9A—C9—H9B	109.5	H29B—C29—H29C	109.5
O8—C9—H9C	109.5	O34—C30—O31	123.8 (8)
H9A—C9—H9C	109.5	O34—C30—C22	123.8 (7)
H9B—C9—H9C	109.5	O31—C30—C22	112.4 (7)
O14—C10—O11	124.2 (7)	O31—C32—H32A	109.5
O14—C10—C2	121.9 (7)	O31—C32—H32B	109.5
O11—C10—C2	113.9 (7)	H32A—C32—H32B	109.5
O11—C12—H12A	109.5	O31—C32—H32C	109.5
O11—C12—H12B	109.5	H32A—C32—H32C	109.5
H12A—C12—H12B	109.5	H32B—C32—H32C	109.5
C6—N1—C2—C3	−0.2 (12)	C26—N21—C22—C23	−0.2 (12)
C6—N1—C2—C10	179.1 (7)	C26—N21—C22—C30	180.0 (7)
N1—C2—C3—C4	−0.2 (13)	N21—C22—C23—C24	−1.1 (13)
C10—C2—C3—C4	−179.4 (7)	C30—C22—C23—C24	178.8 (7)
C2—C3—C4—C5	0.5 (12)	C22—C23—C24—C25	1.7 (12)
C2—C3—C4—I1	−175.6 (6)	C22—C23—C24—I2	−175.7 (6)
C3—C4—C5—C6	−0.5 (12)	C23—C24—C25—C26	−1.2 (12)
I1—C4—C5—C6	175.7 (6)	I2—C24—C25—C26	176.2 (6)
C2—N1—C6—C5	0.2 (12)	C22—N21—C26—C25	0.7 (12)
C2—N1—C6—C7	−179.1 (7)	C22—N21—C26—C27	177.6 (7)
C4—C5—C6—N1	0.1 (13)	C24—C25—C26—N21	0.0 (12)
C4—C5—C6—C7	179.4 (8)	C24—C25—C26—C27	−176.9 (7)
C9—O8—C7—O13	−0.1 (13)	C29—O28—C27—O33	4.0 (12)
C9—O8—C7—C6	−180.0 (7)	C29—O28—C27—C26	−175.7 (7)
N1—C6—C7—O13	176.8 (8)	N21—C26—C27—O33	−179.3 (8)
C5—C6—C7—O13	−2.4 (13)	C25—C26—C27—O33	−2.2 (13)
N1—C6—C7—O8	−3.3 (11)	N21—C26—C27—O28	0.4 (11)
C5—C6—C7—O8	177.4 (8)	C25—C26—C27—O28	177.4 (7)
C12—O11—C10—O14	1.0 (13)	C32—O31—C30—O34	−1.5 (11)
C12—O11—C10—C2	179.8 (7)	C32—O31—C30—C22	177.5 (7)
N1—C2—C10—O14	−174.7 (8)	N21—C22—C30—O34	−166.6 (7)
C3—C2—C10—O14	4.6 (13)	C23—C22—C30—O34	13.6 (12)
N1—C2—C10—O11	6.4 (11)	N21—C22—C30—O31	14.4 (11)
C3—C2—C10—O11	−174.3 (7)	C23—C22—C30—O31	−165.4 (7)