Theoretical study of silicon-oxygen-sulfur oligomers (SiOS)n (n = 1-6)

The geometrical structures and relative stability of the various possible isomers of silicon-oxygen-sulfur oligomers, (SiOS)n (n = 1-6), were studied using quantum chemistry calculations. The linear monomer with Si atom bonding to both O and S atoms is the ground state isomer, and the rhombic chains of four-membered rings are the most stable configurations for n = 2-4, while the hybrid structures by the 4MRs and hexagonal six-membered ring become energetically most favorable for n = 5 and n = 6. Vibrational frequency calculations show that the characteristic IR signatures occur at 1290 cm−1 for n = 1, at the vicinity of 900 cm−1 for n = 2-4, and at about 1080 cm−1 for n = 5-6. These distinctive spectra would provide guide for future experimental detections of these small Si-O-S oligomers.