Uni-, bi- and ter-dentate complexes formed from PPh2CHC(R)=NNHC(=O)PH (R=But or Ph) and Pd or Pt:: crystal structures of [PdCl{PPh2CH2(But)=NN=C(Ph)O}], [Pt{PPh2CH=C(Ph)NN=C(Ph)O}{PPh2CH2C(Ph)=NNHC (=O)Ph}] and [Pd{PPh2CH=C(But)NHNC(=O)Ph}2]

Treatment of the phosphino-N-benzoyl hydrazones PPh2CH2C(R)=NNHC(=O)Ph (R = Bu-t, I; R = Ph, II) with [MCl2(NCPh)(2)] (M = Pd or Pt) gave complexes of type [MCl{PPh2CH2C(Bu-t)=NN=C(Ph)O}] (M = Pd, 1; M = Pt, 2) containing two fused five-membered chelate rings. Metathesis with LiBr or NaI gave [MX{PPh2CH2C(Bu-t)=NN=C(Ph)O}] (X = Br or I; M = Pd or Pt). The complex [PtMe{PPh2CH2C(Bu-t)=NN=C(Ph)O}] (8) was obtained by treating [PtMe2(cod)] (cod = cycloocta-1,5-diene) with one equivalent of I in hot benzene. Treatment of [PtMe2(cod)] with two equivalents of the phosphine II gave [PtMe{PPh2CH2C(Ph)=NNC(=O)Ph}{PPh2CH2C(Ph)=NNHC(=O)Ph] (11), containing a six-membered chelate ring and a unidentate coordinated ligand II. Treatment of [PtCl2(NCMe)(2)] with two equivalents of II in the presence of triethylamine gave [Pt{PPh2CH=C(Ph)N-N=C(Ph)O}-{PPh2CH2C(Ph)=NNHC(=O)Ph] (12), containing a terdentate (P,N,O-bonded) doubly deprotonated ene-hydrazone ligand and a unidentate ligand II. Prolonged treatment of [PdCl2(NCPh)(2)] with two equivalents of I in the presence of triethylamine gave [Pd{PPh2CH=C(Bu-t)NHNC(=O)Ph}(2)] (13), containing two chelated phosphino ene-hydrazide ligands forming six-membered rings. A similar platinum complex, [Pt{PPh2CH=C(But)NHNC(=O)Ph}(2)] (14), was synthesised. The terdentate complexes of [MX{PPh2CH2C(Bu-t)=NN=C(Ph)O}] (M = Pd, Pt; X = Cl, Me) underwent base-promoted (NEt3) Michael-type reactions with MeO2CC=CCO2Me to give terdentate complexes of the type [MX{PPh2CH[C(CO2Me)=CH(CO2Me)]C(Bu-t)=NN=C(Ph)O}] (M = Pd, Pt; X = Cl, Me). The corresponding bromides and iodides were made by metathesis. The crystal structures of 1, 12 and 13 have been determined.