Intermolecular carbon–carbon, nitrogen–nitrogen and oxygen–oxygen non-covalent bonding in dipolar molecules

Abstract

Clear evidence for the existence of intermolecular carbon-carbon (C···C), nitrogen-nitrogen (N···N) and oxygen-oxygen (O···O) interactions between atoms in similar chemical environments in homogeneous dimers of organic dipolar molecules has been obtained from molecular orbital (MO), natural bond orbital (NBO) and atoms-in-molecule (AIM) electron density analyses at the M06L/6-311++G(d,p) level of density functional theory (DFT). These X···X type interactions are mainly the result of local polarization effects, causing segregation of electron-rich and electron-deficient regions in the X atoms, leading to complementary electrostatic interactions. NBO analysis provides evidence of charge transfer between the two X atoms. Even in symmetrical molecules such as acetylene, induced dipoles in the dimer create C···C bonding interactions. The strength of this type of interaction increases with increase in the dipole moment of the molecule. Energy decomposition analysis (EDA) shows that the electrostatic component of the interaction energy (Eint) is very high, up to 95.86%. The C···C interactions between similar carbon atoms are located for several crystal structures obtained from the literature. In addition, MO, AIM and electrostatic potential analyses support interactions between similar oxygen (O···O) and nitrogen (N···N) atoms in a variety of molecular dimers. Good prediction of Eint is achieved in terms of the total gain in electron density at non-covalently interacting intermolecular bonds (∑ρ) and the monomer dipole moment (μ). A rigorously tested QSAR equation has been derived to predict Eint for all dimer systems: Eint (kcal mol(-1)) = -138.395∑ρ(au) - 0.551μ (Debye). This equation suggests that the polarization-induced bonding interaction between atoms in a similar chemical environment could well be a general chemical phenomenon. The results have been further validated by different density functional methods and also by G3MP2 method.

Chemical Reactivity and Quantifying the Intra‐ and Intermolecular Interactions in Zwitterionic Compounds

“…But in order to investigate the donor‐acceptor character of X⋅⋅⋅X intermolecular interactions, the NBO analysis have been devoted for dimer of L 1 using ADF 2017 package with same energy level. For forming a stable donor‐acceptor bond, delocalization of electron density occurs between occupied bond or lone pair NBO orbital and unoccupied antibonding orbital . In case of C(31)⋅⋅⋅C(52) interactions, the interaction between C(31) atom on one molecule with C(52) atom on another molecule corresponds to a charge transfer from the bonding orbitals on H(30) to antibonding orbitals on H(73).…”

Crystal structure, Hirshfeld surface analysis, spectroscopic and biological studies on sulfamethazine and sulfaquinoxaline ternary complexes with 2,2′-biquinoline

“…The disordered water molecule interacts with an SO 2 sulfonamide group in a nonconventional intermolecular O1w•••O114 at a 2.93(1) Å distance (labeled as 11 in Figure 5). Even though this type of interactions is not very common, they play an important role in some supramolecular assemblies 36 .…”

Non-covalent intermolecular carbon–carbon interactions in polyynes

“…In a previous study, we have shown that intermolecular interactions between similar carbon (CÁ Á ÁC), nitrogen (NÁ Á ÁN) and oxygen (OÁ Á ÁO) atoms exists in several organic molecules. 49 The peculiarity of these interactions was that unlike usual intermolecular interactions between an electron rich donor and an electron deficient acceptor atom, the XÁ Á ÁX (where X = C, N and O) interactions are formed between X atoms in similar chemical environments. These interactions were explained as resulting from the complimentary electrostatic interactions between electron rich and electron deficient regions on the interacting monomers.…”