¹³C-NMR Study of Halogen Bonding of Haloarenes. Measurement of Solvent Effects and Theoretical Analysis.

Rainer Glaser*, Naijun Chen, Hong Wu, and Nathan Knotts

Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri, 65211 (USA)

Martin Kaupp*

Institut für Anorganische Chemie, Universität Würzburg, Würzburg, Germany

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Figure legends with embedded web-enhanced objects


Figure 1. The crystal structure of 4-Iodoacetophenone-(4-methoxyphenylethylidene) hydrazone, the (MeO, I)-azine 7, features perfect dipole-parallel alignment within 2-d layers and near-perfect dipole-parallel alignment in the direction in which the layers are stacked. The directionality of the halogen bonding might control the stacking of the layers.


Figure 2. Crystals of (MeO, I)-azine 7 contain halogen bonded strings. The halogen bonding is characterized by d(O-I) = 313.8 pm, (C-O^...I) = 126.28^o, and (O^...I-C) = 171.34^o.


Figure SM-only. Structures of 4-iodoacetophenone imine 9 (B3LYP, MP2), 4-iodoacetophenone hydrazone 10 (B3LYP, MP2), 4-iodoacetophenone 11 (B3LYP, MP2), and 4-iodobenzene 12 (B3LYP, MP2).


Figure SM only. Structures of the azine 4 in C₂- (B3LYP, MP2), C_i- (B3LYP, MP2), and C_2h- symmetry (B3LYP, MP2). Animations of the imaginary vibrations of the C_2h- symmetric structure computed at the MP2 level: Animation 1 and animation 2 of the i31.8 cm^-1 mode; animation 1 and animation 2 of the i21.7 cm^-1 mode. Animations of the imaginary vibration of the C_i- symmetric structure computed at the B3LYP level: Animation 1 and animation 2 i1.9 cm^-1.


Figure 3. Structures of the iodine bonding complexes between DMSO and 4-iodoacetophenone imine 9 (B3LYP, MP2)), 4-iodoacetophenone hydrazone 10 (B3LYP, MP2), 4-iodoacetophenone 11 (B3LYP, MP2), and 4-iodobenzene 12 (B3LYP, MP2). The online version of this paper contains web-enhanced objects that allow for the 3D-display of the DMSO complex of 12 and of its six lowest vibrations with frequencies 7 cm^-1 (torsion mode of the (S-O^...C_ipso-C_ortho) dihedral angle L), 20 cm^-1 (rotational mode about the S-O bond), 22 cm^-1 (S-O^...I angle bending W), 48 cm^-1 (O^...I-C_ipso) angle bending G), 52 cm^-1 (S-O^...I) angle bending in combination with (O^...C_ipso-Ph) bending), and 106 cm^-1 (d(O^...I) stretching mode).

Figure 4. Computed structures of the doubly iodine bonded complexes between two molecules of DMSO and azine 4 in C₂-symmetry (B3LYP, MP2) and C_i-symmetry (B3LYP, MP2).