Lithiation and Li-Doped Effects of [5]Cyclacene on the Static First Hyperpolarizability

On the basis of tubiform [5]cyclacene, a new multilithium salt Li₅-[5]cyclacene and a new electride Li−Li₅-[5]cyclacene are designed in theory. As five Li atoms substituting the five edge H atoms of the [5]cyclacene form the noncentrosymmetric Li₅-[5]cyclacene, the natural bond orbital (NBO) charges of these five Li atoms (Li⁺ = 0.840) show that Li₅-[5]cyclacene is a new multilithium salt. The β₀ value is greatly increased about 1200 times from 7 ([5]cyclacene) to 7938 au (Li₅-[5]cyclacene) by the lithiation effect. Specially, the Li-doped effect on the static first hyperpolarizability in the new electride Li−Li₅-[5]cyclacene has been explored for the first time. An additional Li atom doping into this new tubiform multilithium salt Li₅-[5]cyclacene leads to a new tubiform electride Li−Li₅-[5]cyclacene, and the β₀ value increases about 5 times from 7938 (Li₅-[5]cyclacene) to 35 384 au (Li−Li₅-[5]cyclacene). This shows that the Li-doped effect greatly increases the first hyperpolarizability.