Bonding in Gas-Phase Sulfur Radicals

A series of gas-phase radical sulfur compounds is examined. The bonding is characterized in terms of orbital descriptions, population analysis, vibrational frequencies and energetics. Several different bonding modes are found. As has been seen in the literature previously, 9-S-3 compounds (9 electrons around a 3-coordinate sulfur) may have the unpaired electron centered on just one atom or distributed over two or three centers. Both theoretical studies and the related experimental results are presented. Geometries are tabulated and compared to other compounds with the same elements.