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 NiCl(2)py(4) or PdCl(2)py(2) with organomagnesium or organolithium reagents affords dialkyl complexes cis-MR(2)py(2) (R = Me, CH2SiMe3, CH2Ph, CH2CMe2Ph, 2,4,6-C6H2Me3). The methyl and trimethylsilyl derivatives undergo ligand exchange reactions with chelating nitrogen ligands (alpha-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)(2)py(2) into the metallacyclic derivative NiCH2CMe2-o-C6H4(py)(2). The latter, and the related palladacycle Pd(CH2CMe2-o-C6H4) (cod), also undergo facile ligand exchange reactions. (C) 2003 Elsevier B.V. All rights reserved.