Kinetic versus thermodynamic isomers of the deltahedral dicobaltadicarbaboranes having nine to 12 vertices

► The dicobaltadicarbaboranes Cp2Co2C2Bn−4Hn−2 (n = 9, 10, 11, and 12) have been studied by density functional theory. ► The lowest energy structures for Cp2Co2C2Bn−4Hn−2 (n = 9, 10, and 11) are the most spherical borane deltahedra. ► The low energy Cp2Co2C2Bn−4Hn−2 (n = 9, 10, and 11) structures have the carbon atoms at degree 4 vertices. ► The low energy Cp2Co2C2Bn−4Hn−2 (n = 9, 10, and 11) structures have the cobalt atoms at degree 5 or 6 vertices. ► For the icosahedral Cp2Co2C2B8H10 the lowest energy structures have no Co-Co or C-C edges.