Platinum complexes of ( R)- N, N-bis(2-(diphenylphosphino)ethyl)-1-phenyl-ethylamine: their synthesis and characterisation

Abstract

Both neutral and ionic platinum complexes of ( R)- N, N-bis(2-diphenylphosphinoethyl)-1-phenyl-ethylamine (PNP) were synthesised. In the reaction of PtCl 2(PhCN) 2 and PNP cis-PtCl 2(η 2-P,P-PNP) ( 1) was formed coordinating PNP as a P,P-bidentate ligand. Diastereotopic phosphorus atoms were observed in 31P NMR upon addition of SnCl 2 to the parent complex ( 1) due to the formation of [PtCl(PNP)][SnCl 3] ( 2a). The formation of similar complex cations, [PtX(PNP)] + (where X=I ( 4), CN ( 5)) containing PNP as a terdentate ligand was also observed when KI and KCN was added in the presence of SnCl 2, which formed trichlorostannate counterion. The addition of PPh 3 to 1 resulted in the partial formation of [Pt(PPh 3)(PNP)] 2+ ( 3), which could be accomplished upon addition of SnCl 2. The catalytic activity of the platinum–PNP system in the hydroformylation of styrene is low.