Formation of carbyne complexes in reactions of laser-ablated Os atoms with halomethanes: characterization by C-H(X) and Os-H(X) stretching absorptions and computed structures.

Reactions of laser-ablated Os atoms with halomethanes have been investigated. Small carbyne complexes are produced in reactions of Os atoms with fluoromethanes and identified through matrix infrared spectra and vibrational frequencies computed by density functional theory. The preference for the carbon-osmium triple bond is traced to the low energy of the Os carbyne products. The C-H and C-X stretching absorptions of the carbyne complexes are observed on the high frequency sides of the corresponding precursor bands, which result from the high s character in the C-H bond and interaction between the C-X and C-Os stretching modes, respectively. The calculated Os complex structures show a large variation with the ligands and electronic states, similar to the analogous Ru complex structures. The present report also compares previous Fe, Ru, and Os results and supports the general trend that the higher oxidation state complexes become more stable on going down the family group column.