Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199014705/na1436sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270199014705/na1436Isup2.hkl |
CCDC reference: 142782
Morpholine and β-iodophenylacetylene react exothermically to form a stable 1:1 complex, first prepared by Southwick & Kirchner (1962), who suggested the charge-transfer structure, (I), on the strength of spectroscopic evidence. A single-crystal X-ray diffraction study (Baughman,1964) confirmed structure (I), with a rather short intermolecular N···I contact of ca 2.9 Å. However, the accuracy of the structure, determined by Fourier projections, was not high (R = 0.18).
The present study generally confirmed the earlier one, but is of much higher accuracy and at low temperature. Morpholine molecules related by a b translation, are linked into a chain by N4—H4···O1 hydrogen bonds [N···O 3.110 (3), N—H 0.93, H···O 2.19 Å, N—H—O 173°]. The heterocycle adopts a chair conformation, with the total puckering amplitude (Cremer & Pople, 1975) QT = 0.550 (3) Å. The C18—I bond points directly at the lone electron pair of the N4 atom. The C11—C17≡C18—I···N4 chain is practically linear: the maximum displacement from the best weighted least-squares line through it involves N4 that is 0.207 (4) Å from the line. The angle between this chain and the phenyl plane is 1.9 (2)°. The mean planes of the phenyl and morpholine groups form a dihedral angle of 49.9 (5)°. The I···N4 distance [2.712 (2) Å] proved much shorter than that reported by Baughman (2.9 Å), and is by far the closest intermolecular I···N contact known (with an iodine atom covalently bonded to carbon rather than halogen). The shortest such I···N contacts reported before, 2.93–2.95 Å, involved cyano-group nitrogen (Borgen et al., 1962; Imakubo et al., 1995), and the shortest one involving sp3 nitrogen was 2.99 (3) Å in the urotropine-iodoform complex (Dahl & Hassel, 1970).
The sum of van der Waals radii of I and N, is variously estimated as 3.53 Å (Bondi, 1964), 3.64 Å (Zefirov & Zorkii, 1989) and 3.67 Å (Rowland & Taylor, 1996) in an isotropic model. The 'shape' of the iodine atom is in fact anisotropic, with the smallest size along the continuation of the C—I bond, where a I···N van der Waals contact of 3.36 Å can be expected (Nyburg & Faerman, 1985). By any reckoning, the distance in (I) reveals a strong charge-transfer interaction, probably enhanced by high electronegativity of the ethyne group, estimated as 3.1 in Pauling's scale (Batsanov, 1990), i.e. exceeding that of Cl (3.0).
Data collection: SMART (Siemens, 1996); cell refinement: SMART; data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXTL (Sheldrick, 1995); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Fig. 1. Molecular structure showing 50% probability displacement ellipsoids, and the hydrogen bonds and charge-transfer interactions. |
C8H5I·C4H9NO | Dx = 1.663 Mg m−3 |
Mr = 315.14 | Melting point: 343-353 K K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 8.867 (1) Å | Cell parameters from 470 reflections |
b = 4.8579 (2) Å | θ = 12–23° |
c = 29.390 (2) Å | µ = 2.52 mm−1 |
β = 96.05 (1)° | T = 150 K |
V = 1258.9 (2) Å3 | Plate, colourless |
Z = 4 | 0.32 × 0.30 × 0.12 mm |
F(000) = 616 |
Siemens SMART 1K CCD area detector diffractometer | 3316 independent reflections |
Radiation source: fine-focus sealed tube | 3136 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
Detector resolution: 8 pixels mm-1 | θmax = 29.0°, θmin = 1.4° |
ω scans | h = −12→12 |
Absorption correction: integration (XPREP in SHELXTL; Sheldrick, 1995), before correction Rint = 0.080 | k = −6→6 |
Tmin = 0.520, Tmax = 0.752 | l = −39→30 |
10880 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.058 | H-atom parameters constrained |
S = 1.30 | Calculated w = 1/[σ2(Fo2) + (0.0062P)2 + 1.8187P] where P = (Fo2 + 2Fc2)/3 |
3316 reflections | (Δ/σ)max = 0.001 |
136 parameters | Δρmax = 0.60 e Å−3 |
0 restraints | Δρmin = −0.83 e Å−3 |
C8H5I·C4H9NO | V = 1258.9 (2) Å3 |
Mr = 315.14 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.867 (1) Å | µ = 2.52 mm−1 |
b = 4.8579 (2) Å | T = 150 K |
c = 29.390 (2) Å | 0.32 × 0.30 × 0.12 mm |
β = 96.05 (1)° |
Siemens SMART 1K CCD area detector diffractometer | 3316 independent reflections |
Absorption correction: integration (XPREP in SHELXTL; Sheldrick, 1995), before correction Rint = 0.080 | 3136 reflections with I > 2σ(I) |
Tmin = 0.520, Tmax = 0.752 | Rint = 0.027 |
10880 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.058 | H-atom parameters constrained |
S = 1.30 | Δρmax = 0.60 e Å−3 |
3316 reflections | Δρmin = −0.83 e Å−3 |
136 parameters |
Experimental. The data collection nominally covered over a hemisphere of reciprocal space, by a combination of four sets of exposures; each set had a different φ and/or 2θ angle for the crystal and each exposure covered 0.3° in ω. The crystal-to-detector distance was 4.54 cm. Crystal decay was monitored by repeating 50 initial frames at the end of data collection and analyzing 274 duplicate reflections. |
Refinement. Refinement on F2 for ALL reflections except for 14 with very negative F2 or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating refine_ls_R_factor_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 | ||
I | 0.241246 (19) | 0.58943 (4) | 0.468957 (6) | 0.02788 (6) | |
O1 | 0.2882 (2) | 1.2521 (4) | 0.61565 (7) | 0.0349 (4) | |
C2 | 0.4176 (3) | 1.0834 (8) | 0.61074 (10) | 0.0383 (6) | |
H21 | 0.4271 | 0.9413 | 0.6350 | 0.050* | |
H22 | 0.5105 | 1.1980 | 0.6142 | 0.050* | |
C3 | 0.4027 (3) | 0.9453 (7) | 0.56413 (10) | 0.0321 (6) | |
H31 | 0.4034 | 1.0878 | 0.5401 | 0.042* | |
H32 | 0.4912 | 0.8235 | 0.5619 | 0.042* | |
N4 | 0.2625 (3) | 0.7821 (5) | 0.55599 (8) | 0.0303 (5) | |
H4 | 0.2686 | 0.6334 | 0.5760 | 0.039* | |
C5 | 0.1310 (3) | 0.9520 (7) | 0.56448 (10) | 0.0330 (6) | |
H51 | 0.0394 | 0.8344 | 0.5628 | 0.043* | |
H52 | 0.1145 | 1.0939 | 0.5403 | 0.043* | |
C6 | 0.1524 (3) | 1.0917 (7) | 0.61086 (10) | 0.0357 (6) | |
H61 | 0.0643 | 1.2122 | 0.6144 | 0.046* | |
H62 | 0.1574 | 0.9506 | 0.6353 | 0.046* | |
C11 | 0.2439 (3) | 0.2693 (8) | 0.31857 (10) | 0.0374 (7) | |
C12 | 0.3382 (6) | 0.3976 (11) | 0.29077 (15) | 0.0755 (15) | |
H12 | 0.4017 | 0.5440 | 0.3026 | 0.091* | |
C13 | 0.3414 (7) | 0.3153 (11) | 0.24561 (15) | 0.0820 (16) | |
H13 | 0.4089 | 0.4033 | 0.2272 | 0.098* | |
C14 | 0.2492 (5) | 0.1101 (11) | 0.22743 (12) | 0.0651 (13) | |
H14 | 0.2477 | 0.0627 | 0.1960 | 0.078* | |
C15 | 0.1587 (6) | −0.0271 (12) | 0.25492 (15) | 0.0756 (15) | |
H15 | 0.0977 | −0.1764 | 0.2429 | 0.091* | |
C16 | 0.1559 (5) | 0.0513 (11) | 0.30045 (13) | 0.0632 (12) | |
H16 | 0.0931 | −0.0454 | 0.3193 | 0.076* | |
C17 | 0.2375 (3) | 0.3592 (7) | 0.36494 (10) | 0.0346 (6) | |
C18 | 0.2338 (3) | 0.4460 (7) | 0.40305 (10) | 0.0333 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
I | 0.02880 (9) | 0.03156 (9) | 0.02374 (9) | 0.00131 (8) | 0.00498 (6) | −0.00052 (8) |
O1 | 0.0427 (11) | 0.0279 (10) | 0.0352 (11) | −0.0019 (9) | 0.0091 (9) | −0.0044 (9) |
C2 | 0.0321 (14) | 0.0518 (18) | 0.0299 (14) | −0.0028 (14) | −0.0007 (11) | −0.0034 (14) |
C3 | 0.0236 (12) | 0.0423 (16) | 0.0305 (13) | 0.0053 (11) | 0.0036 (10) | −0.0024 (12) |
N4 | 0.0387 (12) | 0.0251 (11) | 0.0275 (11) | 0.0002 (10) | 0.0054 (9) | 0.0009 (9) |
C5 | 0.0258 (12) | 0.0406 (16) | 0.0331 (14) | −0.0043 (12) | 0.0053 (10) | −0.0041 (12) |
C6 | 0.0340 (14) | 0.0409 (16) | 0.0343 (14) | 0.0008 (13) | 0.0131 (11) | −0.0021 (13) |
C11 | 0.0349 (14) | 0.0524 (19) | 0.0247 (13) | 0.0135 (14) | 0.0027 (10) | 0.0014 (13) |
C12 | 0.114 (4) | 0.075 (3) | 0.044 (2) | −0.022 (3) | 0.039 (2) | −0.015 (2) |
C13 | 0.133 (5) | 0.080 (3) | 0.041 (2) | −0.002 (3) | 0.046 (3) | 0.000 (2) |
C14 | 0.085 (3) | 0.087 (3) | 0.0236 (15) | 0.036 (3) | 0.0068 (17) | −0.0041 (19) |
C15 | 0.074 (3) | 0.113 (4) | 0.040 (2) | −0.009 (3) | 0.0064 (19) | −0.030 (2) |
C16 | 0.060 (2) | 0.097 (3) | 0.0347 (18) | −0.013 (2) | 0.0126 (16) | −0.020 (2) |
C17 | 0.0313 (13) | 0.0438 (17) | 0.0289 (14) | 0.0087 (12) | 0.0039 (10) | 0.0031 (12) |
C18 | 0.0307 (13) | 0.0430 (16) | 0.0265 (13) | 0.0037 (12) | 0.0040 (10) | 0.0015 (12) |
I—C18 | 2.053 (3) | C6—H61 | 0.9900 |
I—N4 | 2.712 (2) | C6—H62 | 0.9900 |
O1—C6 | 1.429 (4) | C11—C12 | 1.378 (5) |
O1—C2 | 1.430 (4) | C11—C16 | 1.388 (6) |
C2—C3 | 1.518 (4) | C11—C17 | 1.438 (4) |
C2—H21 | 0.9900 | C12—C13 | 1.390 (6) |
C2—H22 | 0.9900 | C12—H12 | 0.9500 |
C3—N4 | 1.473 (4) | C13—C14 | 1.362 (7) |
C3—H31 | 0.9900 | C13—H13 | 0.9500 |
C3—H32 | 0.9900 | C14—C15 | 1.370 (7) |
N4—C5 | 1.471 (4) | C14—H14 | 0.9500 |
N4—H4 | 0.9300 | C15—C16 | 1.394 (5) |
C5—C6 | 1.517 (4) | C15—H15 | 0.9500 |
C5—H51 | 0.9900 | C16—H16 | 0.9500 |
C5—H52 | 0.9900 | C17—C18 | 1.201 (4) |
C18—I—N4 | 177.84 (10) | O1—C6—C5 | 110.9 (2) |
C6—O1—C2 | 110.8 (2) | O1—C6—H61 | 109.5 |
O1—C2—C3 | 110.5 (2) | C5—C6—H61 | 109.5 |
O1—C2—H21 | 109.6 | O1—C6—H62 | 109.5 |
C3—C2—H21 | 109.6 | C5—C6—H62 | 109.5 |
O1—C2—H22 | 109.6 | H61—C6—H62 | 108.0 |
C3—C2—H22 | 109.6 | C12—C11—C16 | 118.0 (3) |
H21—C2—H22 | 108.1 | C12—C11—C17 | 120.8 (4) |
N4—C3—C2 | 112.1 (2) | C16—C11—C17 | 121.3 (3) |
N4—C3—H31 | 109.2 | C11—C12—C13 | 120.7 (5) |
C2—C3—H31 | 109.2 | C11—C12—H12 | 119.6 |
N4—C3—H32 | 109.2 | C13—C12—H12 | 119.6 |
C2—C3—H32 | 109.2 | C14—C13—C12 | 120.9 (4) |
H31—C3—H32 | 107.9 | C14—C13—H13 | 119.6 |
C5—N4—C3 | 110.0 (2) | C12—C13—H13 | 119.6 |
C5—N4—I | 112.09 (17) | C13—C14—C15 | 119.3 (4) |
C3—N4—I | 108.20 (16) | C13—C14—H14 | 120.3 |
C5—N4—H4 | 108.8 | C15—C14—H14 | 120.3 |
C3—N4—H4 | 108.8 | C14—C15—C16 | 120.2 (5) |
I—N4—H4 | 108.8 | C14—C15—H15 | 119.9 |
N4—C5—C6 | 112.2 (2) | C16—C15—H15 | 119.9 |
N4—C5—H51 | 109.2 | C11—C16—C15 | 120.7 (4) |
C6—C5—H51 | 109.2 | C11—C16—H16 | 119.6 |
N4—C5—H52 | 109.2 | C15—C16—H16 | 119.6 |
C6—C5—H52 | 109.2 | C18—C17—C11 | 177.0 (4) |
H51—C5—H52 | 107.9 | C17—C18—I | 176.5 (3) |
O1—C2—C3—N4 | −56.5 (3) | C3—N4—C5—C6 | −51.7 (3) |
C2—C3—N4—C5 | 52.2 (3) | N4—C5—C6—O1 | 55.7 (3) |
Experimental details
Crystal data | |
Chemical formula | C8H5I·C4H9NO |
Mr | 315.14 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 8.867 (1), 4.8579 (2), 29.390 (2) |
β (°) | 96.05 (1) |
V (Å3) | 1258.9 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.52 |
Crystal size (mm) | 0.32 × 0.30 × 0.12 |
Data collection | |
Diffractometer | Siemens SMART 1K CCD area detector diffractometer |
Absorption correction | Integration (XPREP in SHELXTL; Sheldrick, 1995), before correction Rint = 0.080 |
Tmin, Tmax | 0.520, 0.752 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10880, 3316, 3136 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.682 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.058, 1.30 |
No. of reflections | 3316 |
No. of parameters | 136 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.60, −0.83 |
Computer programs: SMART (Siemens, 1996), SMART, SAINT (Siemens, 1996), SHELXTL (Sheldrick, 1995), SHELXTL.
I—C18 | 2.053 (3) | C3—N4 | 1.473 (4) |
I—N4 | 2.712 (2) | N4—C5 | 1.471 (4) |
O1—C6 | 1.429 (4) | C5—C6 | 1.517 (4) |
O1—C2 | 1.430 (4) | C11—C17 | 1.438 (4) |
C2—C3 | 1.518 (4) | C17—C18 | 1.201 (4) |
C18—I—N4 | 177.84 (10) | C5—N4—C3 | 110.0 (2) |
C6—O1—C2 | 110.8 (2) | C5—N4—I | 112.09 (17) |
O1—C2—C3 | 110.5 (2) | C3—N4—I | 108.20 (16) |
N4—C3—C2 | 112.1 (2) | C17—C18—I | 176.5 (3) |
Morpholine and β-iodophenylacetylene react exothermically to form a stable 1:1 complex, first prepared by Southwick & Kirchner (1962), who suggested the charge-transfer structure, (I), on the strength of spectroscopic evidence. A single-crystal X-ray diffraction study (Baughman,1964) confirmed structure (I), with a rather short intermolecular N···I contact of ca 2.9 Å. However, the accuracy of the structure, determined by Fourier projections, was not high (R = 0.18).
The present study generally confirmed the earlier one, but is of much higher accuracy and at low temperature. Morpholine molecules related by a b translation, are linked into a chain by N4—H4···O1 hydrogen bonds [N···O 3.110 (3), N—H 0.93, H···O 2.19 Å, N—H—O 173°]. The heterocycle adopts a chair conformation, with the total puckering amplitude (Cremer & Pople, 1975) QT = 0.550 (3) Å. The C18—I bond points directly at the lone electron pair of the N4 atom. The C11—C17≡C18—I···N4 chain is practically linear: the maximum displacement from the best weighted least-squares line through it involves N4 that is 0.207 (4) Å from the line. The angle between this chain and the phenyl plane is 1.9 (2)°. The mean planes of the phenyl and morpholine groups form a dihedral angle of 49.9 (5)°. The I···N4 distance [2.712 (2) Å] proved much shorter than that reported by Baughman (2.9 Å), and is by far the closest intermolecular I···N contact known (with an iodine atom covalently bonded to carbon rather than halogen). The shortest such I···N contacts reported before, 2.93–2.95 Å, involved cyano-group nitrogen (Borgen et al., 1962; Imakubo et al., 1995), and the shortest one involving sp3 nitrogen was 2.99 (3) Å in the urotropine-iodoform complex (Dahl & Hassel, 1970).
The sum of van der Waals radii of I and N, is variously estimated as 3.53 Å (Bondi, 1964), 3.64 Å (Zefirov & Zorkii, 1989) and 3.67 Å (Rowland & Taylor, 1996) in an isotropic model. The 'shape' of the iodine atom is in fact anisotropic, with the smallest size along the continuation of the C—I bond, where a I···N van der Waals contact of 3.36 Å can be expected (Nyburg & Faerman, 1985). By any reckoning, the distance in (I) reveals a strong charge-transfer interaction, probably enhanced by high electronegativity of the ethyne group, estimated as 3.1 in Pauling's scale (Batsanov, 1990), i.e. exceeding that of Cl (3.0).