Iron complexes of terdentate nitrogen ligands: formation and X-ray structure of three new dicationic complexes

• Published in: Polyhedron Vol. 23; no. 18; pp. 3193 - 3199
• Main Authors: Pelascini, F., Wesolek, Manuel, Peruch, F., Cian, A. De, Kyritsakas, N., Lutz, P.J., Kress, J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 02.12.2004; Elsevier
• Subjects: Chemical Sciences; Complexation; Coordination chemistry; Cristallography; Iron; Pyridyl bispyrazolyl; Rearrangement; Terpyridine; X-ray structures; Complexation; Iron; Pyridyl bispyrazolyl; X-ray structures; Terpyridine; Rearrangement
• ISSN: 0277-5387; 0277-5387
• DOI: 10.1016/j.poly.2004.10.001

The synthesis and X-ray structure of the iron complexes ( L 1 ) 2 Fe 2 + ( FeCl 4 - ) 2 , ( L 2 ) 2 Fe 2 + FeCl 4 2 - and ( L 2 ) 2 Fe 2 + ( FeCl 4 - ) 2 ( THF ) 4 (L 1 = 6,6″-di( p-tolyl)-2,2′:6′,2″-terpyridine and L 2 = 2,6-bis-(3-mesitylpyrazol-1-yl)pyridine) are presented. (L 1) 2Fe 2+ was shown to be a high-spin complex, whereas (L 2) 2Fe 2+ was low-spin. Dicationic iron complexes were obtained upon complexation of the ligands 6,6″-di( p-tolyl)-2,2′:6′,2″-terpyridine (L 1) or 2,6-bis-(3-mesitylpyrazol-1-yl)pyridine (L 2) with iron dichloride or iron trichloride. They were characterized by X-ray diffraction and FT-IR spectroscopy. Single crystal structure determinations of ( L 1 ) 2 Fe 2 + ( FeCl 4 - ) 2 , ( L 2 ) 2 Fe 2 + FeCl 4 2 - and ( L 2 ) 2 Fe 2 + ( FeCl 4 - ) 2 ( THF ) 4 all show six-coordinate metal center. These complexes were obtained from L 1FeCl 2 and L 2FeCl 2 during recrystallization attempts. (L 1) 2Fe 2+ was shown to be a high-spin complex, whereas (L 2) 2Fe 2+ was shown to be low-spin. For ( L 2 ) 2 Fe 2 + FeCl 4 2 - , two independent dications of very similar geometry but with distinctive distortion were observed by X-ray analysis.