Synthesis and characterization of a new series of 1D cobalt(II) complexes of pyridine derivative ligands with a single azido bridge and X-ray crystal structure of catena-(μ-N 3)[Co(4-methylpyridine) 4](PF 6)

Abstract

A new series of polymeric cobalt(II) azido complex cations of the formula [CoL 4(N 3)]PF 6– nH 2O ( n=0 or 1), for L=some pyridine derivative ligands, have been prepared and characterized. Solid state electronic spectra suggest six-coordinated cobalt(II) in all complexes. IR spectral results reveal the existence of symmetrical azido ligand, except for complexes of L=3-Etpy and 4-Etpy(red) which contain asymmetrical azides, as well as PF 6 − counter ions in all complexes. X-ray crystal structure determination has shown the complex for L=4-methylpyridine to contain polymeric [CoL 4(N 3)] + cation and PF 6 − anions. In the cation, each cobalt(II) atom is coordinated by four nitrogen atoms from the pyridine ligands and two nitrogen atoms each from a μ-(1,3)-bridging azide giving rise to polymeric chains (1D) of six-coordinate Co(II) polyhedra. The azide ligand is symmetrical [N 1–N 2=N 2–N 3=1.170(3) Å] and linear within experimental error.