organic compounds
2,2′-{(1E,1′E)-[Ethane-1,2-diylbis(azanylylidene)]bis(methanylylidene)}bis(4-iodophenol)
aDepartment of Chemistry, US Air Force Academy, CO, 80840, USA
*Correspondence e-mail: latisha.jefferies@afacademy.af.edu
The title compound, C20H14I2N2O2, a diiodo-Schiff base, crystallizes in Pbca with one molecule per The molecular structure reveals two intramolecular O—H⋯N hydrogen bonds that give the molecule a twisted structure with non-coplanar rings. In the the molecular packing is stabilized by π–π stacking, hydrogen- and halogen-bonding (C—H⋯I; O⋯I) interactions.
Keywords: crystal structure; Schiff base; hydrogen bonding; π–π stacking.
CCDC reference: 2205660
Structure description
2,2′-{(1E,1′E)-[Ethane-1,2-diylbis(azanylylidene)]bis(methanylylidene)}bis(4-iodophenol) (I) (C20H14I2N2O2, Fig. 1) is a salen-type ligand under investigation in our laboratory for possible antimicrobial effects (Ceramella et al., 2022) and the ability to bind to lanthanide metals, which could have other important medicinal properties (Kaczmarek et al., 2018). As a result of the wide range of medical applications for such compounds, and in a continuation of our work in this area (Reimann et al., 2019), the title compound (I) was prepared and its is reported here.
Each molecule of (I) consists of a central ring (C8–C13) with ortho imine nitrogen atoms (N1 and N2) covalently bound through the imine C atoms, C7 and C14 respectively, to I1—Ar(O1—H1) and I2—Ar(O2—H2) rings (Fig. 1). Two intramolecular hydrogen bonds (Table 1), O1—H1⋯N1 [1.842 (15) Å, 152 (3)°] and O2—H2⋯N2 [1.806 (15) Å, 153 (3)°], result in an overall non-planar molecule with the I—Ar(OH) ring planes twisted with respect to the central ring (C8–13) plane [24.97 (7)° versus I1—Ar(O1—H1), and 39.37 (5)° versus I2—Ar(O2—H2)] (Fig. 1). The intramolecular hydrogen bonds of (I) show similarity to those of the dichlorinated Schiff base 3,5-dichloro-N-[2-(methylthio)phenyl]salicylaldimine (Hamaker et al., 2010). Halogen bonding (I1⋯O2) and slipped π–π stacking interactions stabilize the packing pattern. Along the a-axis direction, adjacent molecules related by 21 screw-axis symmetry form 2-stacks/molecule of non-coplanar and alternating central ring (C8–C13) to I2—Ar(O2—H2) ring interactions (Fig. 2). This results in alternating longer [3.821 (13) Å] and shorter [3.734 (13) Å] central ring (C8–C13) centroid to I2—Ar(O2—H2) ring centroid distances with the corresponding alternating centroids slipped by 1.583 (4) and 1.548 (3) Å with respect to each other (Fig. 2). The additional hydrogen bonding provides three shorter and one longer C—H⋯I type interactions in which I2 has a larger displacement ellipsoid than I1 [C18—H18⋯I1 = 3.16 Å (159°), C5—H5⋯I2 = 3.17 Å (156°), C7—H7⋯I2 = 3.23 Å (152°), and C2—H2⋯I2 3.32 Å (131°)]. The two C—I bond lengths of (I) are similar to the C—I bond of 2,3,5,6-tetrafluoro-1,4-diiodobenzene (Tan & Tiekink, 2019). Along the b-axis direction, adjacent molecules appear to be arranged in a H (head, central C8–C13 ring) to T [tail, I1—Ar(O1—H1) and I2—Ar(O2—H2) rings] repeating pattern with the I1 and I2 atoms of the I1—Ar(O1—H1) and I2—Ar(O2—H2) rings interdigitated along the c-axis direction (Fig. 3).
Synthesis and crystallization
To a solution of 2-hydroxy-5-iodobenzaldehyde (4.60 g, 18.5 mmol) in ethanol (200 ml) was added an ethanol (10 ml) solution of o-phenylenediamine (1.00 g, 9.20 mmol), and the reaction mixture brought to reflux with vigorous stirring for 2 h. Upon cooling, the title compound (I) precipitated as an orange solid, and was filtered, washed with ethanol and dried under vacuum. Crystals of (I) suitable for single-crystal X-ray diffraction were grown from acetone layered with hexane. Yield: 4.37 g (83%), m.p. 212–214°C. 1H NMR (500 MHz, CDCl3) δ 8.54 (s, 2H), 7.73–7.54 (m, 4H), 7.37 (q, J = 3.2 Hz, 2H), 7.22 (q, J = 3.2 Hz, 2H), 6.84 (d, J = 9.0 Hz, 2H). [Note: phenolic H atoms (2Hs) undergo rapid exchange thus their NMR signals are broadened into the baseline beyond recognition as reported (Charisiadis et al., 2014).] 13C NMR (500 MHz, CDCl3) δ 162.30, 161.11, 142.25, 141.81, 140.46, 128.32, 121.46, 120.15, 119.63, 79.69. MALDI–TOF MS: monoisotopic m/z calculated for [M + H]+: 568.9; observed: 568.8.
Refinement
Crystal data, data collection and structure .
details of (I) are summarized in Table 2Structural data
CCDC reference: 2205660
https://doi.org/10.1107/S2414314622008951/gg4010sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314622008951/gg4010Isup2.hkl
Data collection: CrysAlis PRO (Rigaku OD, 2019); cell
CrysAlis PRO (Rigaku OD, 2019); data reduction: CrysAlis PRO (Rigaku OD, 2019); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).C20H14I2N2O2 | Dx = 2.025 Mg m−3 |
Mr = 568.13 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 25879 reflections |
a = 7.4776 (1) Å | θ = 1.5–27.4° |
b = 19.1040 (2) Å | µ = 3.39 mm−1 |
c = 26.0919 (3) Å | T = 112 K |
V = 3727.28 (8) Å3 | Rect. Prism, orange |
Z = 8 | 0.30 × 0.26 × 0.12 mm |
F(000) = 2160 |
XtaLAB Synergy, Single source at offset/far, HyPix3000 diffractometer | 4062 independent reflections |
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source | 3774 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.033 |
Detector resolution: 10.0000 pixels mm-1 | θmax = 27.4°, θmin = 1.6° |
ω scans | h = −9→9 |
Absorption correction: gaussian (CrysAlisPro; Rigaku OD, 2019) | k = −23→24 |
Tmin = 0.300, Tmax = 1.000 | l = −32→32 |
34066 measured reflections |
Refinement on F2 | Hydrogen site location: mixed |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.020 | w = 1/[σ2(Fo2) + (0.0133P)2 + 5.3948P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.044 | (Δ/σ)max = 0.002 |
S = 1.09 | Δρmax = 0.66 e Å−3 |
4062 reflections | Δρmin = −0.92 e Å−3 |
242 parameters | Extinction correction: SHELXL-2016/6 (Sheldrick 2015b, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
2 restraints | Extinction coefficient: 0.000120 (17) |
Primary atom site location: dual |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
I1 | 0.48524 (2) | 0.12444 (2) | 0.85138 (2) | 0.01709 (5) | |
I2 | 0.28304 (3) | 0.11138 (2) | 0.30070 (2) | 0.03584 (7) | |
O1 | 0.4758 (2) | 0.15083 (9) | 0.61326 (6) | 0.0205 (4) | |
O2 | 0.1200 (2) | 0.13607 (9) | 0.53361 (6) | 0.0233 (4) | |
N1 | 0.3343 (3) | 0.27475 (10) | 0.62428 (7) | 0.0162 (4) | |
N2 | 0.1963 (3) | 0.26760 (10) | 0.52825 (7) | 0.0163 (4) | |
C1 | 0.4718 (3) | 0.14643 (12) | 0.66467 (9) | 0.0159 (5) | |
C2 | 0.5299 (3) | 0.08468 (12) | 0.68798 (9) | 0.0183 (5) | |
H2A | 0.569184 | 0.046666 | 0.667387 | 0.022* | |
C3 | 0.5307 (3) | 0.07839 (12) | 0.74077 (9) | 0.0181 (5) | |
H3 | 0.571539 | 0.036324 | 0.756275 | 0.022* | |
C4 | 0.4721 (3) | 0.13336 (12) | 0.77109 (9) | 0.0158 (5) | |
C5 | 0.4097 (3) | 0.19424 (12) | 0.74922 (9) | 0.0162 (5) | |
H5 | 0.367238 | 0.231184 | 0.770347 | 0.019* | |
C6 | 0.4087 (3) | 0.20174 (12) | 0.69545 (8) | 0.0154 (5) | |
C7 | 0.3358 (3) | 0.26551 (12) | 0.67317 (8) | 0.0167 (5) | |
H7 | 0.288625 | 0.300786 | 0.694995 | 0.020* | |
C8 | 0.2667 (3) | 0.33732 (12) | 0.60266 (8) | 0.0152 (5) | |
C9 | 0.2710 (3) | 0.40210 (13) | 0.62775 (9) | 0.0190 (5) | |
H9 | 0.316488 | 0.405051 | 0.661683 | 0.023* | |
C10 | 0.2096 (3) | 0.46185 (12) | 0.60350 (9) | 0.0201 (5) | |
H10 | 0.212521 | 0.505533 | 0.620872 | 0.024* | |
C11 | 0.1437 (3) | 0.45812 (12) | 0.55393 (9) | 0.0199 (5) | |
H11 | 0.100415 | 0.499165 | 0.537540 | 0.024* | |
C12 | 0.1408 (3) | 0.39464 (12) | 0.52821 (9) | 0.0192 (5) | |
H12 | 0.095597 | 0.392368 | 0.494231 | 0.023* | |
C13 | 0.2040 (3) | 0.33413 (12) | 0.55195 (8) | 0.0154 (5) | |
C14 | 0.2275 (3) | 0.26073 (12) | 0.47991 (8) | 0.0161 (5) | |
H14 | 0.260311 | 0.300477 | 0.460144 | 0.019* | |
C15 | 0.2129 (3) | 0.19260 (12) | 0.45542 (8) | 0.0156 (5) | |
C16 | 0.1605 (3) | 0.13285 (12) | 0.48342 (9) | 0.0165 (5) | |
C17 | 0.1499 (3) | 0.06804 (12) | 0.45880 (9) | 0.0180 (5) | |
H17 | 0.115967 | 0.027658 | 0.477692 | 0.022* | |
C18 | 0.1884 (3) | 0.06224 (12) | 0.40725 (9) | 0.0186 (5) | |
H18 | 0.181371 | 0.018057 | 0.390663 | 0.022* | |
C19 | 0.2375 (3) | 0.12147 (12) | 0.37979 (9) | 0.0183 (5) | |
C20 | 0.2510 (3) | 0.18604 (12) | 0.40303 (8) | 0.0168 (5) | |
H20 | 0.285889 | 0.225866 | 0.383654 | 0.020* | |
H1 | 0.428 (3) | 0.1892 (8) | 0.6061 (10) | 0.020* | |
H2 | 0.139 (3) | 0.1776 (7) | 0.5419 (9) | 0.020* |
U11 | U22 | U33 | U12 | U13 | U23 | |
I1 | 0.01938 (8) | 0.01833 (8) | 0.01356 (8) | −0.00151 (6) | −0.00173 (6) | 0.00283 (5) |
I2 | 0.07494 (16) | 0.01979 (9) | 0.01279 (9) | 0.00557 (9) | 0.00604 (8) | −0.00114 (6) |
O1 | 0.0249 (9) | 0.0219 (9) | 0.0145 (8) | 0.0034 (7) | 0.0003 (7) | −0.0015 (7) |
O2 | 0.0358 (10) | 0.0204 (9) | 0.0136 (8) | −0.0054 (8) | 0.0043 (7) | 0.0029 (7) |
N1 | 0.0167 (10) | 0.0177 (10) | 0.0142 (9) | −0.0021 (8) | −0.0008 (8) | 0.0004 (8) |
N2 | 0.0172 (10) | 0.0182 (10) | 0.0135 (9) | −0.0003 (8) | −0.0012 (8) | −0.0005 (8) |
C1 | 0.0121 (11) | 0.0218 (12) | 0.0138 (11) | −0.0023 (9) | −0.0012 (9) | −0.0008 (9) |
C2 | 0.0162 (11) | 0.0177 (12) | 0.0211 (12) | 0.0006 (9) | 0.0006 (9) | −0.0046 (9) |
C3 | 0.0149 (11) | 0.0180 (12) | 0.0215 (12) | 0.0000 (9) | −0.0022 (9) | 0.0022 (10) |
C4 | 0.0161 (11) | 0.0187 (11) | 0.0127 (11) | −0.0035 (9) | −0.0009 (9) | 0.0001 (9) |
C5 | 0.0167 (11) | 0.0181 (11) | 0.0138 (10) | −0.0004 (10) | −0.0006 (9) | −0.0010 (9) |
C6 | 0.0145 (11) | 0.0170 (11) | 0.0148 (11) | −0.0020 (9) | −0.0013 (9) | −0.0004 (9) |
C7 | 0.0180 (11) | 0.0171 (11) | 0.0150 (11) | −0.0018 (9) | −0.0005 (9) | −0.0033 (9) |
C8 | 0.0152 (11) | 0.0155 (11) | 0.0149 (11) | 0.0001 (9) | 0.0018 (9) | 0.0008 (9) |
C9 | 0.0203 (12) | 0.0209 (12) | 0.0157 (11) | −0.0029 (10) | 0.0003 (9) | −0.0025 (10) |
C10 | 0.0192 (12) | 0.0163 (11) | 0.0248 (12) | −0.0009 (10) | 0.0035 (10) | −0.0042 (10) |
C11 | 0.0195 (12) | 0.0161 (11) | 0.0241 (12) | 0.0030 (10) | 0.0025 (10) | 0.0041 (10) |
C12 | 0.0205 (12) | 0.0206 (12) | 0.0165 (11) | 0.0016 (10) | −0.0017 (10) | 0.0020 (9) |
C13 | 0.0148 (11) | 0.0165 (11) | 0.0149 (11) | −0.0004 (9) | 0.0020 (9) | 0.0010 (9) |
C14 | 0.0163 (11) | 0.0170 (11) | 0.0150 (11) | −0.0010 (9) | −0.0016 (9) | 0.0023 (9) |
C15 | 0.0147 (11) | 0.0186 (11) | 0.0135 (11) | −0.0010 (9) | −0.0017 (9) | 0.0006 (9) |
C16 | 0.0165 (11) | 0.0193 (12) | 0.0136 (11) | −0.0004 (9) | −0.0006 (9) | 0.0029 (9) |
C17 | 0.0196 (12) | 0.0165 (11) | 0.0179 (11) | −0.0027 (10) | −0.0009 (10) | 0.0036 (9) |
C18 | 0.0202 (12) | 0.0157 (11) | 0.0199 (12) | −0.0005 (9) | −0.0027 (10) | −0.0017 (9) |
C19 | 0.0244 (12) | 0.0188 (12) | 0.0117 (11) | 0.0023 (10) | 0.0005 (9) | −0.0001 (9) |
C20 | 0.0215 (12) | 0.0151 (11) | 0.0138 (11) | −0.0014 (9) | 0.0009 (9) | 0.0015 (9) |
I1—C4 | 2.104 (2) | C8—C9 | 1.401 (3) |
I2—C19 | 2.100 (2) | C8—C13 | 1.405 (3) |
O1—C1 | 1.344 (3) | C9—H9 | 0.9500 |
O1—H1 | 0.835 (10) | C9—C10 | 1.384 (3) |
O2—C16 | 1.345 (3) | C10—H10 | 0.9500 |
O2—H2 | 0.836 (10) | C10—C11 | 1.386 (3) |
N1—C7 | 1.288 (3) | C11—H11 | 0.9500 |
N1—C8 | 1.415 (3) | C11—C12 | 1.386 (3) |
N2—C13 | 1.415 (3) | C12—H12 | 0.9500 |
N2—C14 | 1.290 (3) | C12—C13 | 1.394 (3) |
C1—C2 | 1.397 (3) | C14—H14 | 0.9500 |
C1—C6 | 1.409 (3) | C14—C15 | 1.454 (3) |
C2—H2A | 0.9500 | C15—C16 | 1.411 (3) |
C2—C3 | 1.383 (3) | C15—C20 | 1.402 (3) |
C3—H3 | 0.9500 | C16—C17 | 1.397 (3) |
C3—C4 | 1.386 (3) | C17—H17 | 0.9500 |
C4—C5 | 1.377 (3) | C17—C18 | 1.380 (3) |
C5—H5 | 0.9500 | C18—H18 | 0.9500 |
C5—C6 | 1.410 (3) | C18—C19 | 1.389 (3) |
C6—C7 | 1.456 (3) | C19—C20 | 1.378 (3) |
C7—H7 | 0.9500 | C20—H20 | 0.9500 |
C1—O1—H1 | 105.6 (18) | C9—C10—C11 | 120.2 (2) |
C16—O2—H2 | 104.9 (18) | C11—C10—H10 | 119.9 |
C7—N1—C8 | 120.9 (2) | C10—C11—H11 | 119.9 |
C14—N2—C13 | 120.8 (2) | C10—C11—C12 | 120.1 (2) |
O1—C1—C2 | 118.7 (2) | C12—C11—H11 | 119.9 |
O1—C1—C6 | 122.0 (2) | C11—C12—H12 | 119.8 |
C2—C1—C6 | 119.3 (2) | C11—C12—C13 | 120.3 (2) |
C1—C2—H2A | 119.7 | C13—C12—H12 | 119.8 |
C3—C2—C1 | 120.6 (2) | C8—C13—N2 | 117.7 (2) |
C3—C2—H2A | 119.7 | C12—C13—N2 | 122.5 (2) |
C2—C3—H3 | 120.0 | C12—C13—C8 | 119.7 (2) |
C2—C3—C4 | 120.1 (2) | N2—C14—H14 | 119.8 |
C4—C3—H3 | 120.0 | N2—C14—C15 | 120.5 (2) |
C3—C4—I1 | 119.49 (17) | C15—C14—H14 | 119.8 |
C5—C4—I1 | 119.79 (17) | C16—C15—C14 | 121.2 (2) |
C5—C4—C3 | 120.7 (2) | C20—C15—C14 | 119.6 (2) |
C4—C5—H5 | 120.0 | C20—C15—C16 | 119.3 (2) |
C4—C5—C6 | 120.0 (2) | O2—C16—C15 | 122.0 (2) |
C6—C5—H5 | 120.0 | O2—C16—C17 | 118.4 (2) |
C1—C6—C5 | 119.3 (2) | C17—C16—C15 | 119.6 (2) |
C1—C6—C7 | 121.7 (2) | C16—C17—H17 | 119.8 |
C5—C6—C7 | 119.0 (2) | C18—C17—C16 | 120.5 (2) |
N1—C7—C6 | 120.9 (2) | C18—C17—H17 | 119.8 |
N1—C7—H7 | 119.6 | C17—C18—H18 | 120.2 |
C6—C7—H7 | 119.6 | C17—C18—C19 | 119.5 (2) |
C9—C8—N1 | 123.5 (2) | C19—C18—H18 | 120.2 |
C9—C8—C13 | 119.1 (2) | C18—C19—I2 | 118.35 (17) |
C13—C8—N1 | 117.3 (2) | C20—C19—I2 | 120.16 (17) |
C8—C9—H9 | 119.7 | C20—C19—C18 | 121.5 (2) |
C10—C9—C8 | 120.5 (2) | C15—C20—H20 | 120.2 |
C10—C9—H9 | 119.7 | C19—C20—C15 | 119.6 (2) |
C9—C10—H10 | 119.9 | C19—C20—H20 | 120.2 |
I1—C4—C5—C6 | 176.96 (17) | C8—N1—C7—C6 | −178.7 (2) |
I2—C19—C20—C15 | 177.30 (17) | C8—C9—C10—C11 | −0.3 (4) |
O1—C1—C2—C3 | 178.9 (2) | C9—C8—C13—N2 | −178.1 (2) |
O1—C1—C6—C5 | −179.3 (2) | C9—C8—C13—C12 | −2.5 (3) |
O1—C1—C6—C7 | 3.2 (3) | C9—C10—C11—C12 | −0.7 (4) |
O2—C16—C17—C18 | 179.4 (2) | C10—C11—C12—C13 | 0.0 (4) |
N1—C8—C9—C10 | 177.2 (2) | C11—C12—C13—N2 | 177.0 (2) |
N1—C8—C13—N2 | 6.2 (3) | C11—C12—C13—C8 | 1.6 (3) |
N1—C8—C13—C12 | −178.1 (2) | C13—N2—C14—C15 | −177.7 (2) |
N2—C14—C15—C16 | 1.5 (3) | C13—C8—C9—C10 | 1.8 (3) |
N2—C14—C15—C20 | −178.7 (2) | C14—N2—C13—C8 | −145.5 (2) |
C1—C2—C3—C4 | 0.6 (4) | C14—N2—C13—C12 | 38.9 (3) |
C1—C6—C7—N1 | −3.3 (3) | C14—C15—C16—O2 | 0.7 (4) |
C2—C1—C6—C5 | 1.6 (3) | C14—C15—C16—C17 | −179.2 (2) |
C2—C1—C6—C7 | −176.0 (2) | C14—C15—C20—C19 | 179.9 (2) |
C2—C3—C4—I1 | −177.29 (17) | C15—C16—C17—C18 | −0.7 (4) |
C2—C3—C4—C5 | 1.1 (3) | C16—C15—C20—C19 | −0.3 (3) |
C3—C4—C5—C6 | −1.5 (3) | C16—C17—C18—C19 | −0.2 (4) |
C4—C5—C6—C1 | 0.1 (3) | C17—C18—C19—I2 | −177.10 (17) |
C4—C5—C6—C7 | 177.7 (2) | C17—C18—C19—C20 | 0.8 (4) |
C5—C6—C7—N1 | 179.2 (2) | C18—C19—C20—C15 | −0.6 (4) |
C6—C1—C2—C3 | −1.9 (3) | C20—C15—C16—O2 | −179.1 (2) |
C7—N1—C8—C9 | 29.0 (3) | C20—C15—C16—C17 | 1.0 (3) |
C7—N1—C8—C13 | −155.5 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2A···I2i | 0.95 | 3.32 | 4.009 (2) | 131 |
C5—H5···I2ii | 0.95 | 3.17 | 4.061 (2) | 156 |
C7—H7···I2ii | 0.95 | 3.23 | 4.094 (2) | 152 |
C18—H18···I1iii | 0.95 | 3.16 | 4.066 (2) | 159 |
O1—H1···N1 | 0.84 (1) | 1.84 (2) | 2.609 (3) | 152 (3) |
O2—H2···N2 | 0.84 (1) | 1.81 (2) | 2.580 (3) | 153 (3) |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x, −y+1/2, z+1/2; (iii) −x+1/2, −y, z−1/2. |
Funding information
Funding for this research was provided by: Defense Threat Reduction Agency; Air Force Office of Scientific Research.
References
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