Hybrid tertiary phosphine/secondary amide and amine ligands. their synthesis and coordination chemistry with platinum, palladium, rhodium, and iridium (phosphorus, nitrogen, amido)
Description
The tertiary phosphine/secondary amide and amine hybrid ligands o-(diphenylphosphino)-N-phenylbenzamide (P(CO)NHPh), o-(diphenylphosphino)-N-benzoylaniline (PNH(CPhO), o-(diphenyl- phosphino)-N-phenylbenzylamine (PCNHPh), and o-(diphenyl- phosphino)-N-benzylaniline (PNHBz) have been synthesized and characterized. PNH(CPhO) undergoes N-H oxidative addition with IrL(,2)Cl (L = 2PPh(,3), 2AsPh(,3), 1,2-(Ph(,2)P)(,2)C(,2)H(,4)) to give a mixture of two isomers of the Ir(III) amido hydride(' )Ir PN(CPhO) L(,2)(H)Cl. The possible structures of these isomers are discussed on the basis of their spectroscopic properties (('31)P nmr, ('1)H nmr, and infrared). The reactions of IrL(,2)Cl and the other hybrid ligands give similar results. The oxidative addition reaction of the N-H moiety of a secondary benzamide or aniline and IrL(,2)Cl does not occur in the absence of the chelate effect. Neither PNH(CPhO) nor P(CO)NHPh undergo N-H oxidative addition with either M(cod)Cl (,2) or M(cod)(THF)(,2) - ClO(,4) (M = Rh, Ir; cod = 1,5-cyclooctadiene); instead M(I) phosphine complexes are obtained. The hybrid ligands were used to prepare the chelate-stabilized amido complexes (cod)M(P N)(' )(M = Rh, P(' )N(' )= PN(CPHO), P(CO)NPh; M = Ir, P N = P(CO)NPh) and Ir PN(CPhO) (cod)H(Cl).(' )The properties of these rhodium and iridium complexes are discussed. PNH(CPhO) and P(CO)NHPh coordinate to M(II) (M = Pd, Pt) via the phosphorus atom to give the complexes ML(,2)Cl(,2) (L = hybrid ligand). Deprotonation of the nitrogen atom of these complexes gives the bis(amido) complexes M(P(' )N)(,2) (P N(' )= PN(CPhO), P(CO)NPh). The Pd(II) bis(amido) complexes were also prepared by the reaction of the hybrid ligands and Pd(,2)(dba)(,3) (dba = dibenzylideneacetone). The cyclometallated amido complexes(' )M o-Ph(,2)PC(,6)H(,4)NC(O)C(,6)H(,4) PNH(CPhO) (M = Pd, Pt) have been synthesized. The structure of the Pt complex was determined by a single crystal X-ray diffraction study. The solid state molecular structure is best described as a square pyramid with the NH moiety of the PNH(CPhO) ligand residing in the apical position. A short Pt-H distance of 2.46 A was found, and this interaction may be important in the H/D exchange reaction between the NH proton of these amido complexes and deuterated solvents. The reactivity of the palladium and platinum amido complexes was examined