3-Ferrocenylamido-5-methylpyrazole: synthesis and metal coordination

The synthesis of the 3-ferroceneamido-5-methylpyrazole is reported using 3-amino-5-methylpyrazole and ferrocenecarboxylic acid. The ligand readily forms homo- and hetero-leptic complexes of Zn, Cd, Ni and Co, having ML2 and ML3 stoichiometries. In each case, the ligand acts as a bidentate N,O-chelate. In the solid state, the ferrocene groups form an external Fc-coordination shell surrounding the central metal core. The ligand and all metal complexes exhibit a fully reversible one-electron oxidation at a potential that is sensitive to metal coordination and complex composition.