The dynamic nature of the exohedral η⁶- and the η⁷-complexes of B₄₀ with Cr(CO) ₃ has been explored using density functional theory. The ab initio molecular dynamic simulations were performed at 1200 K to investigate the fluxionality of the heptagonal and hexagonal faces of exohedral B40 complexes. Our computations show that the coordination of the B40 faces with Cr(CO) ₃ fragment reduces its fluxionality to a limited extent. The activation barrier for the inter-conversion of the heptagonal and hexagonal rings in (CO)₃Cr(η⁶-B₄₀) complex is around 15.2 kcal/mol whereas in the (CO)₃ Cr(η⁷-B₄₀) complex, it is slightly higher at around 19.7 kcal/mol. The coordination with another Cr(CO)₃ fragment is found to be equally exergonic, with a barrier for interconversion of 21.5 kcal/mol. The HOMO-LUMO gap is almost similar as the mono-metallated complexes. The di-metallated complexes also show a dynamical behavior of the six and seven membered rings at 1200 K.
Volume 134, 2022
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