THE MECHANISM OF A C-H BOND ACTIVATION REACTION IN ROOM-TEMPERATURE ALKANE SOLUTION

Chemical reactions that break alkane carbon-hydrogen (C-H) bonds are n ormally carried out under conditions of high temperature and pressure because these bonds are extremely strong (similar to 100 kilocalories per mole), but certain metal complexes can activate C-H bonds in alkan e solution under the mild conditions of room temperature and pressure. Time-resolved infrared experiments probing the initial femtosecond dy namics through the nano-and microsecond kinetics to the final stable p roducts have been used to generate a detailed picture of the C-H activ ation reaction. Structures of all of the intermediates involved in the reaction of TpRh(CO)(2) (Tp* = HB-Pz(3)*, Pz* = 3,5-dimethylpyrazoly l) in alkane solution have been identified and assigned, and energy ba rriers for each reaction step from solvation to formation of the final alkyl hydride product have been estimated from transient lifetimes.