Coordinated Hydrazone Ligands as Nucleophiles: Reactions of Fe(papy)2
By Wood, Aaron; Aris, Wasim & Brook, David J. R.
Published in Inorganic Chemistry
2004
Abstract
The diamagnetic iron(II) complexes of the hydrazone ligand pyridinecarboxaldehyde-2'-pyridylhydrazone (papyH) have been characterized by NMR, IR, UV-vis, and electrochemistry. The dication Fe(papyH)22+ undergoes reversible one-electron oxidation at 0.66 V vs internal ferrocene and shows a strong metal-ligand charge-transfer band in the visible region at 524 nm. Deprotonation with NaOH gives diamagnetic, neutral Fe(papy)2 with an oxidation potential of -0.25 V vs internal ferrocene and a charge-transfer band at 603 nm. Fe(papy)2 reacts with active alkylating agents to give dialkyl complexes Fe(papyR)22+ with spectroscopic properties similar to those of Fe(papyH)22+. Monitoring the alkylation by UV-vis reveals the intermediacy of a monoalkylated species.