Figure 4.

Determining the activation energy for oxidative addition of Ni(0) into the aryl halide bond of o-haloaryl pyrrolines. (A) Variable temperature NMR spectra were taken every 2−3 min. Samples were kept in J. Young tubes at indicated temperatures. Characteristic product peaks were fitted and integrated at each time point. (B) Arrhenius analysis gives activation energy from the initial reaction rates obtained at a range of temperatures. The least-squares linear fit to reciprocal temperature against logarithm of the initial rate gave an activation energy of 11 kcal/mol for bromide, and 21 kcal/mol for chloride from the slope parameter.