Nickel spectroscopic terms

However, this equation is in terms of the concentration of NiPh, rather than total nickel, and so does not reflect the actual reaction orders. For orders as eqn 8.54 suggests, the denominator in eqn 8.51 would have to consist exclusively of terms with only CPh2 as co-factor. As eqn 8.52 shows, only three terms meet this condition, and all of them stem from the first matrix row. Accordingly, NiPh, would have to be the macs, contrary to spectroscopic and NMR evidence. Moreover, the other two terms from the first matrix row would also have to be negligible, requiring the first and second step of the cycle to be at quasi-equilibrium. With cat taken to be total nickel, eqn 8.54 can therefore be only a rough approximation, except for catalyst systems in which NiPh4 is indeed the macs and the two first steps are at quasi-equilibrium. 

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