Oligodentate P,N ligands: N,N,N′,N′-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene complexes of rhodium, nickel and palladium

Abstract

The oligodentate P,N ligand N,N,N′,N′-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene reacts with two equivalents of [{Rh(µ-Cl)(COD)}₂], [NiBr₂(DME)] or [PdCl₂(NCMe)₂] (COD = 1,5-cyclooctadiene, DME = dimethoxyethane) in dichloromethane to give the tetranuclear complex [1,3-{cis-Rh(COD)(µ-Cl)₂Rh(PPh₂)₂N}₂C₆H₄] (1) or the dinuclear complexes [1,3-{cis-NiBr₂(PPh₂)₂N}₂C₆H₄] (2) and [1,3-{cis-PdCl₂(PPh₂)₂N}₂C₆H₄] (3), respectively. Compounds 1–3 were characterised by NMR (¹H, ¹³C, ³¹P) and IR spectroscopy. The molecular structure of 2 and 3 shows the formation of a bis-chelate complex with M–P–N–P four-membered rings (M = Pd, Ni). An N,N,N′,N′-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene/Pd(OAc)₂ mixture was used for the copolymerisation of carbon monoxide with ethene or ethylidenenorbornene. Compound 1 was employed as catalyst in the hydrogenation of styrene.