New acylhydridorhodium(III) complexes containing terdentate PNN ligands from the reaction of diolefinic rhodium(I) complexes with o-(diphenylphosphino)benzaldehyde in the presence of chelating amino ligands

[{Rh(cod)Cl}2] (cod=1,5-cyclooctadiene) reacts with o-(diphenylphosphino)benzaldehyde (PPh2(o-C6H4CHO)) (Rh:P=1:1) in the presence of aromatic diamines or 8-aminoquinoline (NN) to give acylhydride [Rh(Cl)(H){PPh2(o-C6H4CO)}(NN)] species. The oxidative addition of PPh2(o-C6H4CHO) in the presence of (NN) and PPh3 gives cationic species [Rh(H){PPh2(o-C6H4CO)} (PPh3)(NN)]+ containing mutually trans phosphorus atoms. When (NN)=8-aminoquinoline, a mixture of two isomers is obtained. These isomers differ in the nitrogen cis to the hydride, amino or quinolinic. By using Rh:PPh2(o-C6H4CHO)=1:2 stoichiometric ratios, oxidative addition of one PPh2(o-C6H4CHO) and P-coordination of another PPh2(o-C6H4CHO) occurs. The aldehyde group undergoes then a condensation reaction with the coordinated amine to afford new PNN terdentate ligands, phosphine-amino-imine when (NN)=diamine or phosphine-diimine when (NN)=8-aminoquinoline. These reactions give selectively the corresponding complexes [Rh(H){PPh2(o-C6H4CO)}(PNN)]+ containing trans phosphorus atoms and the hydride cis to the new imino group. X-ray diffraction studies of the PNN complexes are reported.