Synthesis of triethylphosphite complexes of nickel(II) and palladium(II) with tridentate Schiff base ligand for catalytic application in carbon–carbon coupling reactions

Air stable Ni(II) and Pd(II) complexes viz. [Ni(LS)(P(OEt)3)] (1), [Ni(LN)(P(OEt)3)] (2), [Pd(LS)(P(OEt)3)] (3) and [Pd(LN)(P(OEt)3)] (4) [where LS and LN are dianions of N–(2–mercaptophenyl)salicylideneimine and N–(2–mercaptophenyl)naphthylideneimine respectively] have been synthesized and characterized by analytical and spectral (electronic, FT–IR, 1H, 13C and 31P NMR) methods. The 1H–31P HMBC spectrum established the coupling of phosphorus with the azomethine proton of the Schiff base and the aliphatic protons of triethylphosphite. Novel Ni(II) and Pd(II) complexes exhibited good catalytic activity in Kumada–Tamao–Corriu and Suzuki–Miyaura coupling reactions respectively.