Noncovalent Chelation by Halogen Bonding in the Design of Metal-Containing Arrays: Assembly of Double σ-Hole Donating Halolium with Cu^I-Containing O,O-Donors

Abstract

Five new copper(I) complexescomposed of the paired dibenzohalolium and [CuL2]− (L = 1,2,4-oxadiazolate) counterions in which O,O-atoms of the anion are simultaneously linked to the halogen atomwere generated and isolated as the solid via the three-component reaction between [Cu(MeCN)4](BF4), sodium 1,2,4-oxadiazolates, and dibenzohalolium triflates (or trifluoroacetates). This reaction is different from the previously reported CuI-catalyzed arylation of 1,2,4-oxadiazolones by diaryliodonium salts. Inspection of the solid-state X-ray structures of the complexes revealed the strong three-center X···O,O (X = Br, I) halogen bonding occurred between the oxadiazolate moieties and dibenzohalolium cation. According to performed theoretical calculations, this noncovalent interaction (or noncovalent chelation) was recognized as the main force in the stabilization of the copper(I) complexes. An explanation for the different behavior of complexes, which provide either chelate or nonchelate binding, is based on the occurrence of additional −CH3···π interactions, which were also quantified.

Cyclic Homo- and Heterohalogen Di-λ3-diarylhalonium Structures

“…Another is the chelating mode, i.e., two donor atoms binding to the same halogen site via its mutually perpendicular “vacant” sites . For the simple cyclic structure type B (see Figure ), such scarcely precedented chelating mode was recently explored by the Huber laboratory employing bis-R­(OR′)­CO: donor ligands based on a rigid bis-alkynyl-benzene backbone …”

Isomorphous Structures of Iron(II) Clathrochelates Featuring Terminal σ-Hole Donor Sites and Exhibiting the Cl/Br/I/S Quadruple Heteroisostructural Exchange

“…Noncovalent interactions (abbreviated as NCIs) represent a cutting-edge area of modern science, increasingly identified and applied in catalytic reactions, − production of novel materials, − drug design, − and separation processes. − NCIs affect many properties of organic, organometallic, and coordination compounds such as their stability, solubility, reactivity, conductivity, , and volatility . NCIs also modulate the σ-hole-donating ability of halogens in aromatic systems …”

On-Surface Molecular Recognition Driven by Chalcogen Bonding

“…The second aspect that drives flourishing interest for SBIs relies on the orbital mixing, described as n 2 (Y) → σ*­(E–X) donation involving nonbonding electrons of the electron-rich Y atom, and the antibonding σ E–X * on the E atom (with X being its covalent substituent). Within the category of SBIs, halogen bonding interactions − have demonstrated their efficacy in creating regular supramolecular networks on surfaces, , as revealed by scanning tunneling microscopy (STM) studies highlighting intermolecular Br···O, , Br···Br, , and Br···S halogen bonds (Figure d) governing the self-assembly. However, chalcogen bonding interactions (ChBIs) have not yet demonstrated comparable effectiveness on surfaces as they have in crystal engineering − for developing functional materials, such as supramolecular semiconductors. , Intermolecular Ch···N ChBs acting as the driving force for self-assembling chalcogenazole derivatives on surfaces, have only been theoretically explored in two recent studies. , To the best of our knowledge, the role of ChB interactions in driving self-assembly on surfaces remained largely underinvestigated experimentally when compared to hydrogen bonds, metal coordination bonds, and dipole–dipole interactions, with only two reports suggesting the presence of ChB interactions and other noncovalent contacts. , …”

“… 23 The second aspect that drives flourishing interest for SBIs relies on the orbital mixing, 24 described as n 2 (Y) → σ*(E–X) donation involving nonbonding electrons of the electron-rich Y atom, and the antibonding σ E–X * on the E atom (with X being its covalent substituent). Within the category of SBIs, halogen bonding interactions 25 − 29 have demonstrated their efficacy in creating regular supramolecular networks on surfaces, 30 , 31 as revealed by scanning tunneling microscopy (STM) studies highlighting intermolecular Br···O, 32 , 33 Br···Br, 34 , 35 and Br···S 36 halogen bonds ( Figure 1 d) governing the self-assembly. However, chalcogen bonding interactions (ChBIs) 37 have not yet demonstrated comparable effectiveness on surfaces as they have in crystal engineering 38 − 42 for developing functional materials, 43 such as supramolecular semiconductors.…”