Ultrafast Chelation Dynamics of Cyclopentadienyl Manganese Tricarbonyl Derivatives with Pendant Sulfides


The photoinduced dynamics of two new [η5-C5H 4C(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 μs time scale by UV-pump IR-probe twransient 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 [η5-C5H4C(O)CH 2(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.

Publication Title

Journal of Physical Chemistry B