The photoinduced dynamics of two new [eta(5)-C5H4C(O)R]Mn(CO)(3) complexes 2 (R = CH(SCH3)(2)) and 3 (R = C(SCH3)3) have been investigated in n-heptane solution on the ps to mus time scale by UV-pump IR-probe transient absorption spectroscopy. Irradiation of 2 at 266 or 289 nm induces CO loss to yield two initial products in approximately equal abundance, assigned by their CO-stretching bands to be a heptane solvate of the unsaturated Mn fragment and a ring-formed product in which the pendant sulfide moiety is coordinated to the metal center. In direct analogy with the previously observed behavior of [eta(5)-C5H4C(O)CH2(SCH3)]-Mn(CO)(3) (1), the solvate reacts through a secondary pathway to afford the S-bound product within 200 ns. Irradiation of 3 under identical conditions yields the chelated product exclusively, with no evidence of a competing solvation pathway.