High-spin iron(III) complexes: structural, spectroscopic, and photochemical studies

• Published in: Journal of coordination chemistry Vol. 62; no. 19; pp. 3157 - 3167
• Main Authors: Singh, Udai P., Aggarwal, Vaibhave, Kashyap, Sujata
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 10.10.2009
• Subjects: Azide ligand; Crystal structure; Mononuclear iron complex; Pyrazolylborate
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958970903012793

Reaction of FeCl 3 with one equivalent of acac (acac = pentane-2,4-dionate) and KTp Me2 (Tp Me2 = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate) yielded Tp Me2 Fe(acac)Cl (3), which upon reaction with methanolic solution of sodium azide resulted in the formation of a six coordinate compound Tp Me2 Fe(acac)N 3 (4) with a single azide. When the reaction of FeCl 3 and KTp Me2 was performed with two equivalents of sodium azide and one equivalent of 3,5-dimethylpyrazole (Pz Me2 H), a six coordinate cis azide compound [Tp Me2 Fe(Pz Me2 H)(N 3 ) 2 ] (5) was obtained. These compounds were characterized by spectroscopic methods and single crystal X-ray crystallography. Electrochemical studies of 5 show that it can be irreversibly reduced at relatively lower potential than 4. The photolysis of 5 was performed at 77 K at different wavelengths (480, 419, and 330 nm) showing that 5 was photoreduced to a high-spin Fe(II) species instead of photooxidized to Fe(V).