Erratum: Tuning aromaticity in trigonal alkaline earth metal clusters and their alkali metal salts

Abstract

Page 2766. After several tests, in our previous manuscript,1 we concluded that “the 1A1′(σ) state is the ground state of cyclo-[M3]2− (M = Be, Mg, and Ca) species.” After the publication of our work, Giri et al.2 reported that the triplet state for these cyclo-[M3]2− species is more stable than the singlet one. In view of this conclusion, we revised our results and we find that the triplet state one reaches depends on the initial molecular orbitals (MOs) guess. Thus when one optimizes the triplet state starting from the (MOs) of the 1A1′(σ) state one reaches a different minimum than when the initial MOs are those of the 1A1′(π) state (see Figure 1). The former guess leads to the triplet states that were found in our previous paper1 and that are higher in energy than the 1A1′(σ) states (see Table1). On the other hand, when the triplet states are optimized starting from the MOs of the 1A1′(π) state, one reaches a more stable triplet state that, in fact, is the ground state for these species at both the B3LYP and CCSD(T) levels of theory (see Table2). Notwithstanding, note that for the cyclo-[Ca3]2− compound the singlet state remains more stable than the triplet state at the CCSD(T) level of theory. In fact, among singlet states, the σ-HOMO singlet configuration is the fundamental electronic state for cyclo-[Ca3]2− at the CCSD(T) level of theory (at variance with the cyclo-[Be3]2− and cyclo-[Mg3]2− where the π-HOMO singlet configuration is more stable). In summary, the ground stateof cyclo-[M3]2− species (M = Be and Mg) species is a triplet state and not a singlet one as we erroneously pointed out in our earlier publication.1 Molecular orbital picture of 1A1′(σ) and 1A1′(π) electronic configurations found in cyclo-[M3]2− clusters (M = Be, Mg, and Ca).