Vibronic coupling constants (VCC) in aromatic diboranes are calculated. For a carrier-transporting molecule, vibronic couplings should be small. Vibronic couplings, or reorganization energy, can be controlled by applying the vibronic coupling density (VCD) analysis. To suppress vibronic couplings, electron density difference should be localized not on bonds but on atoms. Aromatic diboranes as electron-transporting molecules are designed based on this design principle. Introducing the protecting groups that prevent the boron atoms in the diborane from being attacked suppresses the vibronic couplings. Based on the nonequilibrium Green’s function (NEGF) theory, energy dissipations through a single molecule are also calculated.