A new inorganic molecule that can be used as a new optical durable molecular switch was theoretically designed in the framework of density functional theory. Two energy minima were found in the molecule, and their electronic states were (1)A(g) and (5)A(1), respectively. The predicted infrared spectra in each state showed that the new inorganic molecule have quite different spectra. This means that the molecule can be used as an optical durable molecular switch.