Endohedral C3 Ca@B39+ and C2 Ca@B39+: axially chiral metalloborospherenes based on B39-

Using the newly discovered borospherenes C-3 B-39(-) and C-2 B-39(-) as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C-3 Ca@B-39(+) (1, (1)A) and C-2 Ca@B-39(+) (2, (1)A), which are the global minimum and the second lowest-lying isomer of Ca@B-39(+), respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca2+@ B-39(-) in nature, with the Ca centre on the C-3 or C-2 molecular axis donating one electron to the B-39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C-3/C-2 Ca2+@ B-39(-) possess the universal bonding pattern of sigma plus pi double delocalization, similar to their C-3/C-2 B-39(-) parents. Molecular dynamics simulations show that both C-3 Ca@B-39(+) (1) and C-2 Ca@B-39(+) (2) are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C-3/C-2 B-39(-). The infrared and Raman spectra of C-3/C-2 Ca@B-39(+) (1/2) are simulated and compared with those of C-3/C-2 B-39(-) to facilitate their forthcoming experimental characterization.