Halogen Bonding Helicates Encompassing Iodonium Cations

Abstract

The first halonium‐ion‐based helices were designed and synthesized using oligo‐aryl/pyridylene‐ethynylene backbones that fold around reactive iodonium ions. Halogen bonding interactions stabilize the iodonium ions within the helices. Remarkably, the distance between two iodonium ions within a helix is shorter than the sum of their van der Waals radii. The helical conformations were characterized by X‐ray crystallography in the solid state, by NMR spectroscopy in solution and corroborated by DFT calculations. The helical complexes possess potential synthetic utility, as demonstrated by their ability to induce iodocyclization of 4‐penten‐1‐ol.

Catalytic Activity of trans-Bis(pyridine)gold Complexes

“…Ligand 4 has been reported to form a monomeric helix when coordinating iodine­(I) [ 4 -I­(I)]­BF 4 . The difference in topology of the [ 4 -Au­(I)] 2 (BF 4 ) 2 dimeric helix from [ 4 -I­(I)]­BF 4 (Scheme ) is corroborated by DFT calculations, which show a thermodynamic preference for formation of a dimeric, double-helical structure for [ 4 -Au­(I)] 2 (BF 4 ) 2 over a monomeric helical complex.…”

“…Ligand 4 has been reported to form a monomeric helix when coordinating iodine(I) [4-I(I)]BF 4 . 42 The difference in topology of the [4-Au(I)] 2 (BF 4 ) 2 dimeric helix from [4-I(I)]BF 4 (Scheme 4) is corroborated by DFT calculations, which show a thermodynamic preference for formation of a dimeric, double-helical structure for [4-Au(I)] 2 (BF 4 ) 2 over a monomeric helical complex. This is most plausibly explained by stronger π-stacking interactions in the double helical [4-Au(I)] 2 (BF 4 ) 2 geometry due to the smaller van der Waals radius of Au(I) as compared to I(I), which favors the monomeric helical structure (for details, see the Supporting Information).…”

“…Here, R may be H ( 1 -H and 2 -H), CF 3 ( 1 -CF 3 and 2 -CF 3 ), CH 3 ( 1 -CH 3 and 2 -CH 3 ), OCH 3 ( 1 -OCH 3 and 2 -OCH 3 ), or asymmetric CH 3 /CF 3 ( 2 -CH 3 /CF 3 ). Ligands 2 – 4 , have previously not been utilized in Au-mediated catalysis.…”

A “nucleophilic” iodine in a halogen-bonded iodonium complex manifests an unprecedented I+···Ag+ interaction

“…cation exchange reaction, and its potential in the design and preparation of the first halonium ion mediated supramolecular capsules [32][33][34][35] and a helicate 36 has recently been demonstrated.…”

Revisiting the covalent nature of halogen bonding: a polarized three-center four-electron bond

“…9 Until now, halogen bonding has been under active investigation. [10][11][12][13][14][15][16][17][18][19][20][21] It plays an essential role in controlling the construction of supramolecular complexes in solid, 2,3,22,23 liquid, [24][25][26][27] and gas phases. 28 Besides, halogen bonding has led to a range of applications in the biological eld, 3,29 such as drug design 30 and protein-ligand complexation.…”