Infrared Spectra and Density Functional Theory Calculations of Group 8 Transition Metal Sulfide Molecules

Small Sulfur molecules were reacted with laser-ablated Fe, Ru, and Os atoms in excess argon and condensed at 7 K. Reaction products were identified from matrix infrared spectra through sulfur-34 isotopic shifts, spectra of sulfur isotopic mixtures, and frequencies from density functional calculations. The strongest absorptions of the MS, disuifide molecules are observed at 540.2, 535.5, and 537.5 cm(-1), respectively, for the group 8 metals, and a 523.2 cm(-1) band is assigned to the FeS vibrational fundamental in solid argon. The FeS,anion was detected in the spectrum at 542.1 cm(-1). The RuS2 absorption exhibited resolved natural ruthenium isotopic splittings. Evidence is also presented for side-bound M(S-2) isomers and MS4 molecules with different structures including Fe(S-2)(2), (S-2)RuS2, and tetrahedral OsS4. Although OsO4 is a well-known molecule, this, we believe, is the first experimental observation Of OSS4.