About the different reactivity of dinuclear palladium and platinum compounds with trispyrrolylphosphine: Synthesis and X-ray crystallographic results of new palladium complexes containing P–pyrrolyl bonds

The reaction of [Pt(μ-Cl)(κ,η2-COE-MeO)]2 (2) (COE-MeO = 2-methoxy-5-cycloocten-1-yl) with trispyrrolylphosphine yields [PtCl{P(pyrl)3}(κ,η2-COE-MeO)] (3), in contrast to the crown-cycle complex [Pd(μ-Cl) {P(pyrl)3}]8 (1) obtained with the analogous palladium complex. The different reactivity has been explained in terms of the higher lability of the carbon–carbon double bond in the starting palladium compound, as compared with the related platinum derivative. The reaction of 1 with the ligand 2-[(pyridin-2-ylmethylene)aminophenol], (HNN′O), in the presence of thalium salt and NEt3, yields the complex [Pd(κ3N,N′,O-py-CHdouble bond; length as m-dashN-C6H4O)(P(O)(pyrl)2)] (5), which contains, for the first time, a di(N-pyrrolyl)phosphonato-P ligand. Treatment of [PdCl(κ3N,N′,O-py-CHdouble bond; length as m-dashN-C6H4O)] with P(pyrl)3 gives the amido derivative [PdCl{κ3P,N,N-(P(pyrl)2-O-C6H4-N-CH(CH2-CO-CH3)-py)}] (7), which displays a N–Pd–P–O–C2 six-membered metallacycle. In addition, the latter compound has been able to insert an acetone molecule into its framework. The crystal structures of 5 and 7 were solved by X-ray diffraction analysis.