Mimicking the C molecule: MB and MB clusters (M = Li, Na) and the reactivity of the N-heterocyclic carbene bound LiB complex.

C has attracted considerable attention from the scientific community for its debatable bonding situation. Herein, we show that the global minima of MB and MB (M = Li, Na) possess similar covalent bonding patterns to C. Because of strong charge transfer from M/M to B dimer, they can be better described as [M][B] and [M][B] salt complexes with the B core surrounded perpendicularly by two and three M atoms, respectively. The energy decomposition analyses in combination with the natural orbital for chemical valence theory give four bonding components in C, MB, and MB clusters. However, the fourth component does not arise from a bonding interaction but from polarization/hybridization. Considering the effect of Pauli repulsion in σ-space, the attractive covalent interaction in these molecules mainly comes from the two π-bonds. We further presented stable N-heterocyclic carbene (NHC) and triphenylphosphine (PPh) ligands bound LiB(NHC) and LiB(PPh) complexes. A comparative study of reactivity towards L = CO, CO, and N between LiB(NHC) and B(NHC) is also performed. L-LiB(NHC) is highly stable against L dissociation at room temperature for L = CO and CO, and the stability is markedly higher than that in L-B(NHC). The larger B→L π-backdonation in L-LiB(NHC) also makes L more activated than in L-B(NHC).