Structures of Co, Pd and Ni complexes with iminopyridine ligands having an hydroxymethyl or acrylate pendant group

Abstract

Co(II), Pd(II) and Ni(II) complexes with iminopyridine ligands have different coordination structures in the solid state, depending on the metal, pendant group of the pyridyl ring and recrystallization conditions. The iminopyridine ligand having an acrylate group, Ar–N CH-2,6-C 5H 3N–CH 2–OCO–CH CH 2 ( L 1 : Ar = 2,6-diisopropylphenyl), forms a Co(II) complex whose metal center has a trigonal pyramidal coordination with two chloride ligands and an N, N’-bidentate ligand L 1 . Both L 1 and the iminopyridine ligand with a CH 2OH pendant on the pyridyl ring, Ar–N CH-2,6-C 5H 3N–CH 2–OH ( L 2 : Ar = 2,6-diisopropylphenyl), coordinate to the PdCl 2 moiety, giving complexes with a square–planar coordination. The reaction of L 1 with [NiBr 2(H 2O) 3] and recrystallization of the products forms crystals which contain mono- and dinuclear complexes with aqua ligands and the N, N’-bidentate ligand. L 2 is coordinated to the Ni(II) center as an N, N’, O-tridentate ligand. Recrystallization of the products of the reaction of L 2 with [NiBr 2(H 2O) 3] with and without excess H 2O in the solution yields crystals of the cationic octahedral complex with two aqua ligands [NiBr(H 2O) 2( L 2 )]Br and the neutral square pyramidal complex [NiBr 2( L 2 )], respectively.