Spectroscopic and electrochemical properties of iron(II) complexes of polydentate Schiff bases containing pyrazine, pyridine and imidazole groups.
We report the synthesis and spectroscopic/electrochemical properties of iron(II) complexes of polydentate Schiff bases generated from 2-acetylpyridine and 1,3-diaminopropane, acetylpyrazine and 1,3-diaminopropane, and from 2-acetylpyridine and L-histidine. The complexes exhibit bis(diimine)-iron(II) chromophores in association with pyrazine, pyridine or imidazole groups displaying contrasting pi-acceptor properties. In spite of their open geometry, their properties are much closer to those of macrocyclic tetraimineiron(II) complexes. An electrochemical/spectroscopic correlation between E degrees (FeIII/II) and the energies of the lowest MLCT band has been observed, reflecting the stabilization of the HOMO levels as a consequence of the increasing backbonding effects in the series of compounds. Mössbauer data have also confirmed the similarities in their electronic structure, as deduced from the spectroscopic and theoretical data.
Souza
Vagner R
VR
Departamento de Química, Universidade Estadual de Maringa, 87020-900 PR, Brazil.
Rechenberg
Hercílio R
HR
Bonacin
Juliano A
JA
Toma
Henrique E
HE
D004563:Electrochemistry / Q000379:methods*; D006639:Histidine / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011719:Pyrazines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012545:Schiff Bases / Q000032:analysis* / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*; D013055:Spectrophotometry, Infrared / Q000379:methods; D015204:Spectroscopy, Mossbauer / Q000379:methods
D007093:Imidazoles; D011719:Pyrazines; D011725:Pyridines; D012545:Schiff Bases; D012997:Solvents; D006639:Histidine; C029899:imidazole; D007501:Iron; C023666:pyridine