Formation of new acylhydride rhodium(III) complexes and hydroxyalkyl derivatives in the reaction of rhodium(I) compounds containing dinitrogen donor ligands with o-(diphenylphosphino)benzaldehyde

The complexes Rh(COD)(NN)Cl (NN=2,2′-bipyridine or 1,10-phenanthroline derivatives) react with o-(diphenylphosphino)benzaldehyde (PCHO) (Rh–PCHO=1:1) to give acylhydride [Rh(Cl)(H)(PCO)(NN)] species. When this reaction is performed in the presence of SnCl2, neutral trichlorostannate compounds with phosphorus trans to tin [Rh(SnCl3)(H)(PCO)(NN)] are obtained and the complexes containing bipyridine derivatives undergo deinsertion of SnCl2 from the RhCl bond in solution. The oxidative addition of PCHO to Rh(COD)(NN)Cl in the presence of PPh3 gives cationic species [Rh(H)(PCO)(PPh3)(NN)]+ containing mutually trans phosphorus atoms. The reaction of Rh(COD)(NN)Cl with PCHO (Rh–PCHO=1:2) affords cationic complexes [Rh(H)(PCO)(PCHO)(NN)]+ where PCHO behaves as P-monodentate ligand and contains a free aldehyde group. The aldehyde group in [Rh(H)(PCO)(PCHO)(bipy)]+, may undergo the insertion reaction into the RhH bond to give the hydroxyalkyl derivative [Rh(PCO)(PCHOH)(bipy)]+.