Diaryliodonium Tetracyanidometallates Self-Assemble into Halogen-Bonded Square-Like Arrays

Abstract

Two diphenyliodonium tetracyanidometallates, [Ph 2 I] 2 [M(CN) 4 ] (M = Ni and Pd), were prepared through anion metathesis. Their X-ray structural analyses show that the structure-defining contact for both crystals is the charge-assisted I•••N halogen bond (HaB) formed between the I atom of the iodonium cations and the N atoms of the CN − ligands. These HaBs assemble the bidentate and 90°-orienting HaB donor Ph 2 I + and the tetradentate, square planar, and 90/180°-orienting HaB acceptors [M(CN) 4 ] 2− into supramolecular rectangles, which further assemble into infinite chains by sharing the vertexes occupied by the [M(CN) 4 ] 2− anions. The noncovalent nature of these contacts was confirmed by density functional theory calculations (M06/def2-TZVP) followed by combined topological analysis of the electron density distribution in the quantum theory of the atoms-in-molecules approach and noncovalent interaction analysis. The philicities of the HaB partners were further verified by the analysis of electron localization function projections, electron density/electrostatic potential profiles along the I•••N bond paths, natural bond orbital analysis, and the natural population analysis or atoms-in-molecules charge sums in model systems.

Controlled Halogen-Bond-Involving Assembly of Double-σ-Hole-Donating Diaryliodonium Cations and Ditopic Arene Sulfonates

“…The naphthalene moiety covalently connects two sulfonate anions, and the overall crystal packing of [ 1 – 3 ] 2 (1,5-NDS) is composed of 1D chains formed by connected heterotetramers (Figure , top, and Figure S1). Similar infinite 1D chains have been already observed in crystals of [Ph 2 I] 2 [M­(CN) 4 ] (M = Ni and Pd) . Compound [ 3 ] 2 (1,5-NDS) crystallizes as a solvated adduct containing two water molecules and one acetone molecule per heterotetrameric unit.…”

“…Similar infinite 1D chains have been already observed in crystals of [Ph 2 I] 2 [M(CN) 4 ] (M = Ni and Pd). 52 Compound [3] 2 (1,5-NDS) crystallizes as a solvated adduct containing two water molecules and one acetone molecule per heterotetrameric unit. Despite the greater dimensionality of the interactional landscape occurring in this crystal (water molecules form short and expectedly strong hydrogen bonds with sulfonate oxygen atoms, Figure 2).…”

“…Halogen bonding (abbreviated as XB) has found a broad spectrum of applications in diverse fields of chemistry including crystal engineering, , design and fabrication of functional materials − (e.g., phosphorescent systems and perovskite solar cells), ion recognition, − noncovalent catalysis, − and drug design. , Hypervalent halogen compounds (especially I III -based species, i.e., λ 3 derivatives) are particularly interesting as XB-based tectons because they can function as double-σ-hole-donating XB species , (biaxial donors in another terminology) and this feature has been exploited in catalysis, ,,, organic synthesis, materials science, and crystal engineering. ,− …”

“…Specifically, we employed the isomeric 1,5- and 2,6-naphthalenedisulfonates as XB-accepting counterions of double-σ-hole XBs donating diaryliodonium cations. A related approach has recently been utilized for the construction of extended arrays in crystals of [Ph 2 I] 2 [M­(CN) 4 ] (M = Ni and Pd); other cases wherein di- and tetratopic XB acceptors were used have been reported in the past five years. − …”

Periodate anions as a halogen bond donor: formation of anion⋯anion dimers and other adducts

“…We decided to make a major step forward and to identify tetrahedral and anionic s-hole donors wherein the donor atom is a p block element. Moving from the interest in hypervalent iodine compounds, [15][16][17] we decided to explore the s-hole donor ability of anionic iodine in its highest oxidation state, i.e. in the periodate anion.…”