Topological analysis of the electron density in the chromium–manganese chalcogenide clusters, [E2CrMn2(CO)9]−2 (E = S, Se, Te)

• Published in: Theoretical Chemistry Accounts
• Main Author: Al-kirbasee N.E.; Hassan A.H.; Al-Ibadi M.A.M.; Abood E.S.; Sirat S.S.
• Format: Article
• Language: English
• Published: Springer Science and Business Media Deutschland GmbH 2024
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85195781797&doi=10.1007%2fs00214-024-03129-6&partnerID=40&md5=7ad036edf3dfd0c35d8f70f1eac905b0

The nature of the chemical bonding interactions in the trigonal–bipyramidal chromium–manganese chalcogenide clusters, [E2CrMn2(CO)9]−2 (E = S, Se, and Te), has been studied using two methods of the quantum chemical topology analysis: electron density q(r) and electron localization function (ELF). The evaluation of these properties reveals important details about chemical bond interactions within the clusters. According to the results, it has been confirmed that the bonding between Mn–Mn and Mn–Cr is absent in all three trinuclear clusters 1–3. The presence of bridging chalcogenide atoms (S, Se, and Te) concerning M–M is a key factor in determining the distribution of electron densities. This factor has a significant impact on the formation of bonds between these transition metal atoms. Calculations of the non-negligible delocalization index for clusters 1–3 confirm a 5c–12e bonding interaction that is delocalized over the five-membered CrMn2(μ−E)2 ring. In clusters 1–3, the M–E bonds between Mn and Cr metal atoms and E ligands (S, Se, and Te) exhibit similar topological parameters that are comparable to that of pure covalent single bonds between nonmetal atoms. Furthermore, the source function calculations reveal that the bonded E atoms contribute the most at each Mn–E and Cr–E bcps, with a small contribution from the bonded metal atom and OCO atoms. Interestingly, non-bonded transition metal atoms act as sinks rather than sources of electron density. The M…OCO delocalization indexes and SF calculations indicate significant CO to M π-back-donation. This work aims to provide insights into the interactions between Mn–Mn and Mn–Cr, and the changes in bonding interactions across the di-bridging chalcogen elements series. It also aims to examine the role of carbonyl groups in M–M interaction within the clusters. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.