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(2) disulfide 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(2)(-) anion was detected in the spectrum at 542.1 cm(-1). The RuS(2) absorption exhibited resolved natural ruthenium isotopic splittings. Evidence is also presented for side-bound M(S(2)) isomers and MS(4) molecules with different structures including Fe(S(2))(2), (S(2))RuS(2), and tetrahedral OsS(4). Although OsO(4) is a well-known molecule, this, we believe, is the first experimental observation of OsS(4).