Resonance bonding in XNgY (X = F, Cl, Br, I; Ng = Kr or Xe; Y = CN or NC) molecules: an NBO/NRT investigation

Abstract

Several noble-gas-containing molecules XNgY were observed experimentally. However, the bonding in such systems is still not understood. Using natural bond orbital and natural resonance theory (NBO/NRT) methods, the present work investigated bonding of the title molecules. The results show that each of the studied XNgY molecules should be better described as a resonance hybrid of ω-bonding and [Formula: see text]-type long-bonding structures: X: Ng - Y, X - Ng: Y, and XY. The ω-bonding and long-bonding make competing contributions to the composite resonance hybrid due to the accurately preserved bond order conservation principle. We find that the resonance bonding is highly tunable for these noble-gas-containing molecules due to its dependence on the nature of the halogen X or the central noble-gas atoms Ng. When the molecule XNgY consists of a relatively lighter Ng atom, a relatively low-electronegative X atom, and the CN fragment rather than NC, the long-bonding structure XY tends to be highlighted. In contrast, the heavy Ng atom and high-electronegative X atom will enhance the ω-bonding structure. Overall, the present work provides electronic principles and chemical insights that help understand the bonding in these XNgY species.

Long‐bonding and effects of carbon hybridization on the bonding of MNgC compounds (M = Cu, Ag, Au)

“…In addition, it was well-known that in the linear bonding motif X Ng Y there exists long bonding between X and Y across the Ng [32][33][34][35][36][37]. In the classical Ng insertion compounds FNgF and HNgX(X = F, Cl, Br, I) [33] there is large bond order between the two end atoms, the bonding patterns in these molecules can be represented by three resonance structures, two ω structures and one σ structure, thus there exists 3c 4e long bonding in these compounds.…”

“…During this time, several key works contributed to the development of noble gas chemistry, including Pauling's theoretical prediction of the existence of the noble gas fluorides in 1933 [1], Neil Bartlett's successful synthesis of Xe + [PtF 6 ] − in 1962 [2], and Räsänen's synthesis of HArF using HF photocatalysis in Ng matrix in 2001 [3]. In recent years, many compounds formed by noble gases and various chemical elements have been synthesized experimentally and/or predicted theoretically [3–37]. It seems that noble gases can bond with every element in the periodic table and plug into any bond to form insertion compounds.…”