Resumen
A recent computational paper (Kalita et al., Phys. Chem. Chem. Phys. 2020, 22, 24178?24180) reports the existence of a quadruple bond between a carbon and an iron atom in the FeC(CO)3" role="presentation" style="position: relative;">33
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molecule. In this communication, we perform several computations on the same system, using both density functional theory and post-Hartree?Fock methods and find that the results, and in particular the Fe-C bond length and stretching frequency depend strongly on the method used. We ascribe this behavior to a strong multireference character of the FeC(CO)3" role="presentation" style="position: relative;">33
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ground state, which explains the non-conclusive results obtained with single-reference methods. We therefore conclude that, while the existence of a Fe-C quadruple bond is not disproved, further investigation is required before a conclusion can be drawn.