π Effects Involving Rh−PZ3 Compounds. The Quantitative Analysis of Ligand Effects (QALE)

Document Type

Article - Merrimack Access Only

Publication Title


Publication Date


Abstract/ Summary

Through the quantitative analysis of ligand effects (QALE), we have probed π effects associated with Rh-P bond lengths, νCO, and -∆Hrx for Rh(CO)(Cl)(PX3)2 and νCO and -∆Hrx for Rh(acac)(CO)(PZ3). It was found that π effects are complex and depend strongly on the nature of ancillary or other participatory groups. The results of the QALE analysis of -∆Hrx point out the importance of synergistic interactions between PZ3 and other ancillary ligands in accord with theoretical computations. Literature data for Rh(CO)(Cl)(PZ3)2 have been supplemented with new values of ∆Hrx for PMe3 (-75.6 ± 0.3 kcal/mol), P(i-Pr)3 (-68.7 ± 0.3 kcal/mol), and PCy3 (-66.4 ± 0.4 kcal/mol) as well as crystal structures for Rh(CO)(Cl)- (P(i-Pr3))2 (Rh-P ) 2.3488(3) Å) and Rh(CO)(Cl)(PCy3)2 (Rh-P ) 2.3508(3)).