Density functional theory calculations of dodecaboronyldodecaborate (B-12(BO)(12)(2-)) were performed to examine its electronic properties. Formation of this dianion with unusually high stability was accomplished by substituting boronyl (BO) for H in a typical dianion, B12H122-. The binding energy of the second electron of the B-12(BO)(12)(2-) dianion was 5.89 eV (PBE0/def2-TZVP) and 5.96 eV (MN12-SX/def2-TZVP); this represents its stability and is the largest value reported to date. We clarify that the high stability of B-12(BO)(12)(2-) originates from the weak pi orbital interaction character of the BO ligand. All calculated results clearly indicate the deficient pi orbital interaction ability of BO. (C) 2018 Elsevier B.V. All rights reserved.