Reaction of [RhCl(CO)2]2 or [RhCl(COD)]2 with o-(diphenylphosphino)benzaldehyde. Formation of hemiaminals in the subsequent reaction with dihydrazones

Abstract [RhCl(CO) 2 ] 2 reacts with o -(diphenylphosphino)benzaldehyde (PCHO) to afford a monocarbonylated rhodium(I) complex containing P-monodentate PCHO, trans -[RhCl(CO)(PCHO) 2 ] ( 1 ) while [RhCl(COD)] 2 undergoes the oxidative addition of one PCHO, with displacement of 1,5-cyclooctadiene, and coordination of the second PCHO molecule as P-(σ-aldehyde) chelate to give [RhH(PCO)Cl(PCHO)] ( 2 ) which contains trans P-atoms. Compound 2 reacts with H 2 NNCHCHNNH 2 (gdh) to give selectively a complex [RhH(PCO)(Pgdh)] + containing a stable hemiaminal in a new tridentate ligand, Pgdh, coordinated via the imino nitrogens and the phosphorus and the atom. The reaction of Rh(COD)(gdh)Cl with PCHO gives a mixture of the hemiaminal containing compound and the hydroxyalkyl complex [Rh(PCO)(PCHOH)(gdh)] + which contains trans P-atoms and is formed from precursors containing cis P-atoms. The transformation of the hemiaminal group in [RhH(PCO)(PNN)] + (PNN=Pgdh or Ppvdh (pvdh, H 2 NNCHC(CH 3 )NNH 2 )) into imine to give new tridentate PaNN ligands in complexes [RhH(PCO)(PaNN)] + has also been studied.