The photochemistry of five diruthenium hexacarbonyl tetrahedrane compounds, Ru 2 (CO) 6 (μ-S 2 C 6 H 4 ) (1), Ru 2 (CO) 6 (μ-S 2 C 2 H 4 ) (2), Ru 2 (CO) 6 (μ-S 2 C 3 H 6 ) (3), Ru 2 (CO) 6 (μ-SCH 2 CH 3 ) 2 (4), and Ru 2 (CO) 6 (μ-dmpz) 2 , (5), where dmpz=3,5-dimethylpyrazolate, have been examined in frozen Nujol glasses at ca. 90 K. Compounds 1-4 are found to lose CO upon UV photolysis to form two isomeric photoproducts, while 5 is found to form one product almost exclusively. The various photoproducts are assigned to axial and equatorial CO-loss species on the basis of the spectra of analogous triphenylphosphine pentacarbonyl derivatives.