Kinetics of the substitution of norbornadiene in tetracarbonyl(norbornadiene)molybdenum(0) by 2,2 '-3-bipyridine

The kinetics of the thermal substitution of norbornadiene (nbd) by 2,2 ' -b ipyridine (2,2 ' bipy) in (CO)(4)Mo(C7H9) was studied by quantitative FT-IR and UV-VIS spectroscopy. The reaction rate exhibits first-order dependence on the concentration of the starting complex, and the observed rate consta nt depends on the concentration of both leaving nbd and entering 2,2 ' -bip y ligand. The mechanism was found to be consistent with the previously prop osed one, where the rate determining step is the cleavage of one of the two Mo-olefin bonds. The reaction was performed at four different temperatures (35 - 50 degreesC) and the evaluation of the kinetic data gives the activa tion parameters which now support an associative mechanism in the transitio n states.