MB16 - (M = Sc, Y, La): Perfect Bowl-like Boron Clusters.

The introduction of transition-metal doping has engendered a remarkable array of unprecedented boron motifs characterized by distinctive geometries and bonding, particularly those heretofore unobserved in pure boron clusters. In this study, we present a perfect (no defects) boron framework manifesting an inherently high-symmetry, bowl-like architecture, denoted as MB16- (M = Sc, Y, La). In MB16-, the B16 is coordinated to M atoms along the C5v-symmetry axis. The bowl-shaped MB16- structure is predicted to be the lowest-energy structure with superior stability, owing to its concentric (2π+10π) dual π aromaticity. Notably, the C5v-symmetry bowl-like B16- is profoundly stabilized through the doping of an M atom, facilitated by strong d-pπ interactions between M and boron motifs, in conjunction with additional electrostatic stabilization by an electron transfer from M to the boron motifs. This concerted interplay of covalent and electrostatic interactions between M and bowl-like B16 renders MB16- a species of exceptional thermodynamic stability, thus making it a viable candidate for gas-phase experimental detection.