Abstract
The reaction of the starting materials [CoII(Porph)] (Porph = alpha,alpha,alpha,alpha-tetrakis(o-pivalamidophenyl) porphyrin (TpivPP) and the meso-tetraphenylporphyrin (TPP)) with an excess of 4,4'-bipyridine in chlorobenzene leads to the creation of two cobalt(II) derivatives: [CoII(alpha,beta,alpha,beta-TpivPP)(4,4'-bpy)(2)]center dot C6H5Cl center dot C6H14 (1) and [Co-II(TPP)(4,4'-bpy)(2)]center dot 2bpy (2). These compounds have been characterized by UV-vis, IR, H-1 NMR and MALDI-TOF spectroscopy. The proton NMR spectra of (1) and (2) clearly indicated that these derivatives are paramagnetic while the UV-vis data confirmed creation of a new six-coordinated or penta-coordinated Co(II)-meso-porphyrin complexes by displaying red shifted Soret bands. The determined X-ray structures of (1) and (2) show that in the solid state these species are considered as coordination polymers which consist of 1D chains of alternating [Co-II(Porph)] and 4,4'-bipyridine molecules located at the axial positions of the cobalt(II) coordination sphere. The coordination geometry of Co(II) in (1) and (2) is octahedral; the porphyrin (TpivPP or TPP) acts as a tetradentate chelating ligand with four nitrogen atoms from the pyrrole moieties occupying the equatorial positions along the porphyrin core. The N-donor atoms of the 4,4'-bipyridine create the axial ligands. It is noteworthy that for complex (1) the starting porphyrin is the alpha,alpha,alpha,alpha-TpivPP atropisomer but the final coordination polymer contains the alpha,beta,alpha,beta-TpivPP conformer.