Since (heteroatom substituted) secondary phosphine oxides [(HA)SPOs] frequently occur as crucial decomposition products of commercially and industrially relevant trivalent P-ligands, this ligand class was studied with regard to its influence in the rhodium catalyzed hydroformylation. The following three topics were subject to investigations with five electronically modified SPOs and one representative HASPO:
a) the tautomeric equilibrium
b) the model ligand´s coordination chemistry with rhodium(I) precursors
c) the behaviour of (HA)SPOs in the rhodium catalyzed hydroformylation.
Besides characterization of isolated products these studies were supported by modern in situ analysis techniques (HP-NMR and HP-IR spectroscopy) as well as DFT calculations.