New mixed-donor unsymmetrical P–N–P ligands and their palladium(II) complexes

Abstract

Unsymmetrical bidentate ligands R₂P(E)–N(H)–P(E′)R₂^′ [R, R′  = Ph, OPh, ⁱPr; E, E′  = O, S, Se] have been synthesised using the condensation reaction of an amino compound, R₂P(E)NH₂ [R = PhO, Ph; E = O, S, Se], with a phosphorus electrophile, R₂^′P(E′)Cl [R′  =  ⁱPr, Ph, OPh; E′  = O, S, Se]. Deprotonated ligands (with KO^tBu) can be treated with Pd(OAc)₂ to give [Ph₂P(S)–N–P(O)(OPh)₂]₂Pd, [ⁱPr₂P(S)–N–P(O)(OPh)₂]₂Pd and [Ph₂P(S)–N–P(S)(OPh)₂]₂Pd, which show either four-membered or six-membered chelate rings. The new compounds were studied spectroscopically (NMR, IR and Raman) and by X-ray crystallography.