The IR spectra of the products formed when molecular fluorine was passed over tantalum and ruthenium heated to 100-1100 degreesC and isolated in inert matrices at 12 K were studied. In the Ta + F-2 system, bands of (TaF5)(3), TaF5, and TaF4 were observed. In the Ru + F-2 system, the major reaction product was monomeric ruthenium pentafluoride. The structures of metal fluorides of various compositions are discussed