DFT and CCSD(T) study of the disilicon trihydride (Si2H3) isomerization, unprecedented isomeric structures

The total potential energy surface (PES) of the disilicon trihydride Si2H3 is explored in order to study the isomerization of this system at B3LYP/6-311+G(3df,2p) and CCSD(T)//DFT levels of theory. Eight minima and 11 transition states (TSs) are detected on the total potential energy surface (PES). Some of them neither have been observed experimentally nor theoretically before, because of the total PES flatness. All these minima and TSs are connectable on the total PES via small energetic barriers. This gives a fluxional behaviour to Si2H3 system which could have some spectroscopic complications especially in NMR analysis. The HSiSi(η2-H2)-like isomer confers to Si2H3 the H2-complex properties but it undergoes a rapid transformation via a small activation barrier.