P(OPh)3 substitution at [Rh(β-diketonato)(cod)] complexes: The relationship between kinetics and frontier orbitals

The energy of the highest occupied molecular orbital of [Rh(β-diketonato)(cod)] relates to the experimental second order substitution rate constant (k2) for a series of [Rh(β-diketonato)(cod)] complexes in the [Rh(β-diketonato)(cod)] + 2P(OPh)3 → [Rh(β-diketonato)(P(OPh)3)2] + cod reaction: EHOMO (eV) = −0.125 ln k2 (dm3 mol−1 s−1) − 3.73. ln k2 also relates to the sum of the DFT calculated charges (Mulliken, NPA, Hirshfeld, Voronoi and Bader) on the Rh(cod) fragment of [Rh(β-diketonato)(cod)]. Linear equations obtained for this [Rh(β-diketonato)(cod)] series of compounds may be used for theoretical estimation of substitution rates for similar complexes.