On the kinetics and mechanism of the conversion of Cr(CO)(5)(kappa(1)-P-dppm) to Cr(CO)(4)(kappa(2)-P,P'-dppm) (dppm=1,2-diphenylphosphinomethane): an alternative hypothesis

摘要

The data from a previously reported kinetic evaluation dealing with the conversion of Cr(CO)(5)(kappa(1)-P-dppm) (1: dppm = 1,2-diphenylphosphinomethane) into the corresponding chelated complex Cr(CO)(4)(kappa(2)-P,P'-dppm) (2), via CO loss, is re-evaluated. The conclusion is that the process is more likely to involve a rate-determining step that is first-order in [Cr(CO)(5)(kappa(1)-P-dppm)], as opposed to the previously reported zero-order model as proposed. This implies CO loss from 1, by presumably either an I (d) or more likely a Dissociative (D: S (N) 1-type) mechanism, leads to 2. This hypothesis is compared and contrasted to reported data and comparisons are made to similar processes involving related Group VI metal carbonyl species.