Synthesis of dialkyl, diaryl and metallacyclic complexes of Ni and Pd containing pyridine, α-diimines and other nitrogen ligands: Crystal structures of the complexes cis-NiR2py2 (R=benzyl, mesityl)

The alkylation of NiCl2py4 or PdCl2py2 with organomagnesium or organolithium reagents affords dialkyl complexes cis-MR2py2 (R=Me, CH2SiMe3, CH2Ph, CH2CMe2Ph, 2,4,6-C6H2Me3). The methyl and trimethylsilyl derivatives undergo ligand exchange reactions with chelating nitrogen ligands (α-diimines or 2-imidoylpyridines), yielding the corresponding dialkyl derivatives in good to excellent yields. A catalytic amount of PMe3 induces the transformation of the nickel complex Ni(CH2CMe2Ph)2py2 into the metallacyclic derivative .The latter, and the related palladacycle , also undergo facile ligand exchange reactions.