Electronic structure and photochemical reaction intermediates of octakis(1,1,2-trimethylpropyl)octasilacubane

The electronic spectrum and photochemical reaction intermediates of octakis(1,1,2-trimethylpropyl)octasilacubane have been studied by analyzing the UV-VIS spectrum and transient absorption spectra. The first three absorption bands of the UV-VIS spectrum have been assigned to the transitions from HOMO (t1u symmetry) to LUMO (a2u), from HOMO-1 (t1g) to LUMO, and from HOMO to LUMO+1 (t2g) by making reference to the results obtained by INDO/S-CI calculations. The photochemical reaction intermediate has been elucidated to be the isomer whose decay rate constant is 57±3 s−1. The quenching rate constant of the isomer by oxygen is ca. 3×105 M−1 s−1.