The Theoretical Investigation by QTAIM Approach to Chemical Bonding of a Di-Rhenium Bis(Triphenylphosphine) Carbonyl Cluster Containing Sulfuric and Hydrido Bridge: [Re2(CO)6(μ-S)(μ-H)(PPh3)2]

Abstract

Scientists used the quantum theory of atoms in molecules (QTAIM) to calculate and interpret various electron density parameters for a di-rhenium bis(triphenylphosphine) carbonyl cluster containing sulfuric and hydrido bridge: [Re₂(CO)₆(μ-S)(μ-H)(PPh₃)₂]. They analyzed the bond critical points and compared them with data from previous organometallic system studies. The researchers were able to compare the topological processes of different atom-atom interactions based on these results.

The calculations showed that there were no bond critical points or identical bond paths between Re-Re in the core of the cluster. The electron density distribution was affected by the position of bridging hydride and sulfur atoms coordinated to Re-Re, which significantly affected the bonds between these transition metal atoms. However, the calculations did confirm the presence of a 6c–8e bonding interaction delocalized over HRe₂SP₂ in the cluster.

The scientists found that the Re-H and Re-S bonds in this cluster exhibited typical closed-shell interactions, with small values for ρ(b) and Laplacian ∇²ρ(b) above zero and small positive values for total energy density H(b). Similarly, the bond interactions between phosphine metal atoms and the C atoms of the phenyl ring ligands showed properties similar to open-shell interactions in the QTAIM classification.