Reply to the Comment on “Realization of Lewis Basic Sodium Anion in the NaBH₃⁻ Cluster”

Abstract

We reply to the comment by S. Pan and G. Frenking who challenged our interpretation of the Na−:→BH3 dative bond in the recently synthesized NaBH3− cluster. Our conclusion remains the same as that in our original paper (https://doi.org/10.1002/anie.201907089 and https://doi.org/10.1002/ange.201907089). This conclusion is additionally supported by the energetic pathways and NBO charges calculated at UCCSD and CASMP2(4,4) levels of theory. We also discussed the suitability of the Laplacian of electron density (QTAIM) and Adaptive Natural Density Partitioning (AdNDP) method for bond type assignment. It seems that AdNDP yields more sensible results. This discussion reveals that the complex realm of bonding is full of semantic inconsistencies, and we invite experimentalists and theoreticians to elaborate this topic and find solutions incorporating different views on the dative bond.

The Na⋅⋅⋅B Bond in NaBH3−: A Different Type of Bond

“…Methods: All structure were optimized at M06‐2X [29] /aug‐cc‐pVTZ [30, 31] (def2‐TZVPP [32] for all atoms of KBH 3 − ) and were found to be local minimum on their potential energy surfaces on the basis of the Hessian of their energy. The structural parameters were found to be in good agreement with those obtained from high‐level ab initio computations as reported by Bowen and co‐workers, see Supporting Information for structural parameters [13, 19] . Although Bowen and co‐workers had argued that NaBH 3 − has some degrees of multireference character in its equilibrium geometry, using DFT for analyzing the electron delocalization index and relevant parameters in this particular case is not problematic.…”

“…Pan and Frenking employed the energy decomposition analysis, EDA, [18] to analyze Na−B bond; however, EDA itself is not a reliable approach for two reasons: First, as Bowen and co‐workers later emphasized, NaBH 3 − even at its equilibrium bonding distance suffers from some degrees of multireference character, which increases with stretching the bond. Therefore, the DFT‐based EDA scan cannot be trusted for the bond dissociation process as it is shown in the reply to the comment by Bowen and his co‐workers [19] . The EDA energy components are path functions and their magnitude change by changing the process of EDA [20] .…”

On the stability and chemical bond of noble gas halide cations NgX+ (Ng = He – Rn; X = F – I)

“…For this, we performed natural population analysis (NPA) scans from 1 to 4 Å. This method recently applied by Boldyrev et al and Frenking et al respectively, [ 49–51 ] allows to understand the dissociation process in terms of electron distribution. As can be seen in the NPA‐scan of ArBr + (Figure 1), when the atoms are at a distance of 1 Å, their charges are similar, but as the atoms move away it is possible to observe that Br reaches positive (+1) charge, while the final charge for Ar is zero.…”

The Na⋅⋅⋅B Bond in NaBH3−: A Different Type of Bond

“…Therefore, the DFT-based EDA scan cannot be trusted for the bond dissociation process as it is shown in the reply to the comment by Bowen and his coworkers. [19] The EDA energy components are path functions and their magnitude change by changing the process of EDA. [20] Therefore, EDA is not a reliable method for characterization of bonding in novel molecules.…”

“…The structural parameters were found to be in good agreement with those obtained from high-level ab initio computations as reported by Bowen and co-workers, see Supporting Information for structural parameters. [13,19] Although Bowen and coworkers had argued that NaBH 3 À has some degrees of multireference character in its equilibrium geometry, using DFT for analyzing the electron delocalization index and relevant parameters in this particular case is not problematic. The reason is that using multireference methods only reduces the degree of electron delocalization that is the degree of covalency as it has been reported earlier by Francisco et al [33] Therefore, I expect that using a multireference method merely lower the degree of observed electron sharing, that is, even less covalent character.…”