Stabilization of polyiodide chains via anion⋯anion interactions: experiment and theory

Abstract

In tyrosinium polyiodide hydrate, cations and anions aggregate in layers. The cation layers are stabilized by classical hydrogen bonds. The anionic part of the structure consists of parallel infinite polyiodide strands; the distance pattern along these chains suggests the presence of smaller subunits I 3 − , I 2 and I − . Comparative calculations for small fragments and longer chains in frozen geometries indicate that this unexpected arrangement is favoured by local stabilizing anion⋯anion interactions and partial charge transfer between the subunits. The topological analyses of the electron density ρ, its negative Laplacian L = −∇ 2 ρ and the electrostatic potential φ functions have been used to study the intrachain I-I and I⋯I interactions. Thorough analysis carried out with L indicates the successive arrangement of generalized charge concentration and charge depletion sites (for either L > 0 or L < 0 regions) along bond paths, and permits to distinguish iodides from iodine atoms even when they are involved in intermediate situations where interatomic distances and net charges are not conclusive.

Quantum Crystallography: Current Developments and Future Perspectives

“…In the widely used QTAIM theory, [193] this kind of analysish as been deeplyd eveloped for 1ðr)t oc haracterize many aspects that this functione xhibits in atoms,m olecules and their interactions. [212,213] Thus, in the polyiodide chains of the crystal structure of tyrosinium polyiodide hydrate (Figure 10 b), iodines are distinguished from iodides by the type of CPs found in their interactions with surrounding atoms. Hence, the study of the topological critical points (CP) of r 2 1 r ðÞhas indicated that charge concentration (CC) and charge depletion (CD) sites found in the valence shell of atoms are drivingg eometric preferences of molecules in the solid state.…”

“…Hence, the study of the topological critical points (CP) of r 2 1 r ðÞhas indicated that charge concentration (CC) and charge depletion (CD) sites found in the valence shell of atoms are drivingg eometric preferences of molecules in the solid state. [214] Furthermore, the intersection of the gradient vector fields of 1 r ðÞ and V r ðÞ has shown to help to understand the counterintuitive assembling of anion-anion and cation-cation aggregates, [215][216][217][218] pointing out the regions of space that are involved in local attractive electrostatic interactions in hydrogen [219] and halogen [212] bonding. [212,213] Thus, in the polyiodide chains of the crystal structure of tyrosinium polyiodide hydrate (Figure 10 b), iodines are distinguished from iodides by the type of CPs found in their interactions with surrounding atoms.…”

“…[221] Combining different experiments is aw ay to overcome limited resolution and leads to more precise modelso fs pin or spin-resolved electron densities. [212]with permission from the Royal SocietyofChemistry; Figure 10 All these promisingd evelopments should not mask several critical aspects. These experimental modelsa re of utmost importance to test high-level theoretical calculations, as recently shown for ap aramagnetic radical.…”

“…[211],Copyright2 013 American Chemical Society; Figure 10 breproduced from Ref. [212]with permission from the Royal SocietyofChemistry; Figure 10 Concept can imagine to include in this approachexperimental magnetic structuref actors.…”

Pressure‐Induced Polymerization and Electrical Conductivity of a Polyiodide

“…Different theoretical approaches to study bonds in PIs exist, for example,calculations of the potential energy surface and bond order, [5] energy decomposition analysis (EDA), [6] analysis of the electron density and its Laplacian at bond critical points (BCP), [7] theelectron localization function, and the one-electron potential. [8] Furthermore,t he energy den-…”