Halogen Bonding Assembles Anion⋅⋅⋅Anion Architectures in Non‐centrosymmetric Iodate and Bromate Crystals

Abstract

Single crystal X‐ray diffraction of iodate and bromate salts shows that the I and Br atoms in IO3− and BrO3− anions form short and linear O−I/Br⋅⋅⋅O contacts with the O atoms of nearby anions. Non‐centrosymmetric systems are formed wherein anions are orderly aligned into supramolecular 1D and 2D networks. Theoretical evidences, namely the outcome of QTAIM and NCIplot studies, prove the attractive nature of these contacts and the ability of iodate and bromate anions to act as robust halogen bond (HaB) donors. The HaB is proposed as a general and effective assisting tool to control the architecture of acentric iodate salts.

Chalcogen and Hydrogen Bond Team up in Driving Anion⋅⋅⋅Anion Self‐Assembly

“…Se is involved in a Janus- À and IO 3 À anions in respective salts. [18] While in 1 a • 2 a,b salts HB and ChB alternate in binding anions along the supramolecular chain (namely the supramolecular synthons depicted in Scheme 1c-top are adopted), in 4-hydroxypyridinium H-selenite 1 a • 2 c the two interactions both connect adjacent HSeO 3 À anions (namely the supramolecular synthon depicted in Figure 1c-bottom is adopted) (Figure 3 This behaviour [24] is likely promoted by the quite tight network of HBs between dianions 1 b and dications 2 d. Two short and symmetry related ChBs assemble two adjacent diselenite dianions into tetraanionic dimers [7] between simulated and experimental powder X-ray diffraction spectra (see SI).…”

“…[9] In recent years it emerged that formation of anion-anion (or cation-cation [10] ) adducts can be driven also by σ-hole interactions, [11,12] the bondings between electron rich sites (nucleophiles) and the electron poor regions (σ-holes) that atoms have opposite to the σ covalent bonds they are involved in. Discrete adducts as well as 1D or 2D networks are obtained starting from anions wherein the atom bearing the σ-hole is of the 7, [13,14] 13, [15,16] or 17 [17,18] group of the periodic table (the respective σ-hole interactions are typically named matere bond (MaB), triel bond (TrB), and halogen bond (HaB)). For instance, tri-and tetra-oxyanions XO 3 À and XO 4 À (e. g., X=Br, I, Mn, Re) form, in the solid, dimers and chains via doubly pinned supramolecular synthons (when their X=O moieties undergo antiparallel pairing (Scheme 1b-left)) and via singly pinned synthons (when the O of one anion gets close to the X of another anion (Scheme 1b-right)).…”

Osme Bond: Geometric and Energetic Features in the Adducts between OsO4 and Lewis Bases

“…These regions, where the electrostatic potential is frequently positive, can interact attractively with electron‐rich atoms or moieties. Interestingly, σ‐ and π‐holes interactions involving very polarizable atoms seem to be so strong that they can occur also in negatively charged species as perrhenate, [4] periodate, [5] iodate, [6] H‐selenite [7] and AuCl 4 − anions [8] …”

Exploring Unconventional σ‐Hole Interactions: Computational Insights into the Interaction of XeO3 with Non‐Aromatic Coordinating Solvents

“…The localized region of positive electrostatic potential, which is positioned on a σ* orbital on the extension of a covalent bond between the recipient atom bound to an electron‐withdrawing atom/group, also known as a sigma hole, gives rise to the NCIs (Figure 1, left) [15] . These include halogen, chalcogen, pnictogen, tetrel, icosagen (or triel), and, more recently, spondium, regium, and aerogen bonds [16–25] …”