Phenomenal Observation of Attractive Intermolecular CH⋯HC Interaction in a Mercury (II) Complex: An Experimental and First‐Principles Study

Abstract

The nature of the attractive intermolecular CÀ H…HÀ C interaction, which could affect the crystal packing and solid-state molecular structure, is yet unknown. Here, a novel mercury (II) complex including N-(2-biphenyl)pyrazine-2-carboxamide ligand, one such system, has been synthesized and characterized by a single crystal X-ray diffraction. The existence of attractive intermolecular CÀ H⋯HÀ C interaction (-2.64 to À 9.30 kj/mol depending on computational levels) is a notable feature in the crystal packing of this complex, which is the first observation of intermolecular CÀ H⋯HÀ C interaction in a metal complex. From crystallographic data, this contact has a distance of 2.172 Å which is 9.5% shorter than the sum of the van der Waals radii of two hydrogen atoms, which is the primary condition of having intermolecular interactions. We study the nature CÀ H… HÀ C interaction in the synthesized mercury (II) complex using periodic/non-periodic density functional theory in conjunction with quantum theory of atoms in molecules, non-covalent interaction reduced density gradient method, natural bond orbital, and energy decomposition analysis tools. Our results suggest that CÀ H⋯HÀ C interaction has closed-shell, donoracceptor, and van der Waals nature.[a] Prof.

Arsenic-Involving Intermolecular Interactions in Crystal Structures: The Dualistic Behavior of As(III) as Electron-Pair Donor and Acceptor

“…Bader’s quantum theory of atoms in molecules (QTAIM) has plenty of applications in analyzing chemical bonds and interactions. This method has been employed by chemists from different research fields to obtain a novel perception of chemical bonds and interactions. − A bond critical point (BCP) is a saddle point of the electron density along a bond path between two atoms. The existence of a BCP between two interacting atoms is one of the signs of a chemical bond or interaction. − The properties of BCPs indicate all kinds of chemical bonds and interactions such as closed-shell bonds (vdW interactions, ionic bonds) and shared bonds (covalent bonds): , e.g., the magnitude of electron density at the BCP (ρ BCP ) designates closed-shell interactions (ρ BCP < 0.10 au) or shared (covalent) interactions (ρ BCP > 0.20 au). , The sign of the Laplacian of the electron density at a BCP (∇ 2 ρ BCP ) classifies a contact as a closed-shell interaction if the Laplacian is positive (∇ 2 ρ BCP > 0) or as a shared interaction if the Laplacian is negative (∇ 2 ρ BCP < 0). , These criteria are, however, not strictly reliable; thus, there are additional criteria related to QTAIM.…”

The Unconventional Noncovalent Interactions Control: Crystallographic and Theoretical Analyses of the Crystalline Structure of 1,1′‐(1‐Chloro‐4‐methoxyphenyl)dibenzene as a Case Study

“…Moreover, CÀ H…HÀ C contacts which represent a unique type of CÀ H … X hydrogen bonding, have engendered a stimulating debate among researchers, [17][18][19][20] with supporting evidence for their stabilizing contribution. [21][22][23][24] These dispersion-dominated interactions exhibit hydrogen bonding-like characteristics and have notable application in various fields, including synthetic chemistry, [25] crystal engineering, [26,27] and hydrogen storage materials [28] etc. Furthermore, unconventional halogen-halogen (X⋯X) interactions have been the subject of considerable interest for many years.…”