Electron-transfer chain catalysis in phosphine replacement reaction: Determination of relative donor capability of arylpyridylphosphines

The slight differences in the donor capabilities of PPhnPy3−n (n = 0–3) could be measured directly in the equilibrium of phosphine replacement reaction on (η5-C5H5)Fe(CO)2-phosphine complexes, taking advantage of the radical pathway to establish equilibrium rapidly. The simultaneous determination of equilibrium constants is done in a single experiment. The donor capability increases in the order PPh3 < PPh2Py < PPhPy2 < PPy3 with quantified View the MathML source(η5-C5H5)Fe(CO)2+-affinity scales at 1, 4.90, 11.0, and 20.3, respectively.