Anion–π Interactions in Salts with Polyhalide Anions: Trapping of I₄²⁻

Abstract

The directionality of interaction of electron-deficient π systems with spherical anions (e.g,. halides) can be controlled by secondary effects like NH or CH hydrogen bonding. In this study a series of pentafluorophenyl-substituted salts with polyhalide anions is investigated. The compounds are obtained by aerobic oxidation of the corresponding halide upon crystallization. Solid-state structures reveal that in bromide 2, directing NH-anion interactions position the bromide ion in an η(1)-type fashion over but not in the center of the aromatic ring. The same directing forces are effective in corresponding tribromide salt 3. In the crystal, the bromide ion is paneled by four electron-deficient aromatic ring systems. In addition, compounds 4 and 6, which have triiodide and the rare tetraiodide dianion as anions, are described. Computational studies reveal that the latter is highly unstable. In the present case it is stabilized by the crystal lattice, for example, by interaction with electron-deficient π systems.

Coherent ultrafast lattice-directed reaction dynamics of triiodide anion photodissociation

“…In our study, this scenario is more plausible for light species like I • than its diatomic co-product I 2 −• with an adjacent I 3 − , because the excess translation energy imparted to I 2 −• from bond-breaking will, according to momentum conservation, grant it only half of the recoil velocity as I • , and it will be further slowed down by the Coulombic repulsion from I 3 − . The alternative two-body dissociation channel (I 3 − ℎ � � I 2 + I − ) contains a distinct monatomic fragment, the iodide anion (I − ), but its reactivity is low and the formation of the dianion I 4 2− through an analogous bimolecular association pathway, I − + I 3 − ⇌ I 4 2− , is thermodynamically discouraged 34,35 . Furthermore, the other photofragment, I 2 , will generate the well-characterized absorptive signal in the region of 500-600 nm from its major absorption bands 36 , and will follow different kinetics with respect to the spectral in condensed phases [9][10][11][12]14,22,38 .…”

Transformative Binding and Release of Gold Guests from a Self‐Assembled Cu8L4 Tube

“…This complex could be prepared under identical conditions to those used to make 2 when AgBF 4 was substituted for Cu(CH 3 CN) 4 BF 4 . The titration of AgBF 4 into an acetonitrile solution of 2 resulted in the displacement of Cu I by Ag I within the guest, allowing the stability constant of 4.2 10 10 m À3 for 3 to be obtained, 34 times greater than that of 2; the larger Ag I center appears better stabilized by van der Waals contacts and favorable interactions with the p-electron density [21] of the host framework than the smaller Cu I . The 13 C NMR spectrum of 3 prepared using 13 C-labeled dicyanoaurate was consistent with a NC-Au-CN-Ag-NC-Au-CN guest structure, wherein the signals of the carbon atoms closest to silver were further split due to coupling to the NMR-active silver centers ( Figures S34 and S35).…”

An Adaptable and Dynamically Porous Organic Salt Traps Unique Tetrahalide Dianions

“…Similarly, when the diiodide salt 1 a of the 1,6-bis(trimethylammonium)hexane cation (hereafter the hexamethonium, HMET 2+ , cation) reacts with one equivalent of I 2 , the salt 3 a is formed. [5] Formation of the poorly stable, [6] halogen-bonded [I 4 ] 2À dianion is favored both by size matching [7] of the interacting charged moieties (the N +…”