Combined σ- and π-Hole Donor Properties of Perfluorinated Iodo(or bromo)benzenes: Halogen Bonding and π-Hole Interactions in Cocrystals Including Cu₄I₄ Clusters

Abstract

Cocrystallization of CuI with NCNMe2 in the presence of 1,4-diiodotetrafluorobenzene (1,4-FIB) and 1,4-dibromotetrafluorobenzene (1,4-FBrB) in MeCN gave cocrystals [Cu4I4(NCNMe2)4]·1,4-FIB, [Cu4I4(NCNMe2)2(NCMe)2]·1,4-FIB, and [Cu4I4(NCNMe2)4]·1,4-FBrB, whose solid-state structures were studied by X-ray diffraction. In these three cases, the perfluorinated haloarenes function as combined σ- and π-hole donors, and their crystal structures exhibit intermolecular contacts, including halogen bonding (HaB) and π-hole interactions with the iodine ligands of the copper clusters. Analysis of the theoretical calculation data indicated that the formation of (cubane)·(perfluorinated haloarene) π–hole dimer is slightly energetically more favorable than (cubane)·(perfluorinated haloarene) HaB-based σ-hole dimer. The π-hole contacts and HaBs are accompanied by additional hydrogen bonding and also π-hole­(NCN)···X (X = Br, I) contacts. Altogether, these interactions lead to the occurrence of moderately strong noncovalent binding between copper clusters and the aromatic HaB donors.

Transition from covalent to noncovalent bonding between tetrel atoms

“…Particularly when dealing with noncovalent interactions, it has been found useful to consider how the molecular electrostatic potentials (MEPs) of the two constituent monomers might best align with one another. 26–33 The MEPs of the three charge states of SnCl 2 are illustrated in Fig. 7.…”

Metal-Bound Sulfur and Selenium Sites as Halogen Bond Acceptors: The Supramolecular Association of Rhodium(I) Half-Lantern Complexes with 1,4-Diiodotetrafluorobenzene

“…The second pattern type (most common) is the association of a HaB donor with metal-bound atoms (Figure b). In general, it involves linkages between halogen atoms of a HaB donor and halide anions ,− (I/Br···X; X = Cl, Br, I) or oxygen atoms in, e.g., ReO 4 – , acetate, or β-diketonate − ligands (I···O or I/Br···(O,O)).…”

Quantum chemical analysis of noncovalent bonds within crystals. Concepts and concerns

“…A typical example of some of these ideas is provided by a very recent study of a crystal containing perfluorinated iodo and bromobenzenes 46 and their interactions with Cu 4 I 4 clusters which are held together by CH⋯F and CH⋯Br HBs, I⋯Br XBs, and I⋯π contacts, amongst others. AIM analysis of segments of the clusters provided bond critical point parameters that were then related by an empirical relationship to estimate energies of each individual contact.…”