High pressure study of Ru3(CO)12 by x-ray diffraction, Raman, and infrared spectroscopy

The single-crystal X-ray structure of Ru-3(CO)(12) is reported at 8 pressures ranging from 1 atm (0.0 GPa) to 8.14(5) GPa. Although intramolecular bonding parameters remain relatively constant, intramolecular and intermolecular nonbonding contact distances decrease by an average of 4% and 15%, respectively. At 8.14 GPa, (OO)-O-..., (CO)-O-..., and (CC)-C-... intermolecular distances as short as 2.54(4), 2.64(6), and 3.07(4) Angstrom, respectively, are observed, and the unit cell compresses to 75% of the ambient pressure volume. Raman and infrared spectroscopic measurements show that carbonyl stretching frequencies shift to higher wavenumber values by as much as 80 cm(-1), even though Ru-C and C-O distances stay roughly constant throughout the entire pressure range studied. Compression of the sample to above 18 GPa with laser radiation results in an irreversible transformation due to either decomposition or a total collapse of D-3h molecular geometry accompanied by color darkening.