How Cationic Metalloligands Affect the Coordination of Lewis Basic Ligands in Rh^I Complexes

A series of RhI complexes featuring cationic diphosphinometal ligands (PMPn+) has been synthesized, and the effect of the dative RhI → Mn+ interactions on other ligands coordinated to the RhI center were studied. The Rh–CO bond strength in square pyramidal [(PMP)­Rh­(CO)­X]n+-type complexes (X = Cl, H) is dominated by the charge of the metalloligand. Complex [(PZnP)­Rh­(CO)­H]­(NTf2)2 (7) was evaluated for its competence in hydroformylation catalysis. Computational analysis of octahedral [(PMP)­Rh­(CO)2H]n+ model complexes revealed a strengthening of the Rh–CO bond trans to the metalloligand with increasing atomic number of the metalloligand.