Structure, stability, and nature of bonding in carbon monoxide bound EX3+ complexes (E = group 14 element; X = H, F, Cl, Br, I)

Abstract

A density functional theory study is performed to predict the structures and stability of carbon monoxide (CO) bound urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0002 (E = C, Si, Ge, Sn, Pb; X = H, F, Cl, Br, I) complexes. The possibility of bonding through both C- and O-sides of CO is considered. Thermochemical analysis reveals that all the dissociation processes producing CO and urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0003 are endothermic in nature whereas most of the dissociation reactions are endergonic in nature at room temperature. The nature of bonding in EC/O bonds is analyzed via Wiberg bond index, natural population analysis, electron density, and energy decomposition analyses in conjunction with natural orbitals for chemical valence scheme. In comparison to CO stretching frequency ( urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0004) in free CO, while a red shift is noted in O-side binding, the C-side binding results in a blue shift in urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0005. The relative change in urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0006 values in CO bound urn:x-wiley:01928651:media:jcc24446:jcc24446-math-0007 complexes on changing either E or X is scrutinized and possible explanation is provided in terms of polarization in the σ- and π-orbitals and the relative strength of C→E or O→E σ-donation and E→C or E→O π-back-donation.