Axial ligand mediated switchable rotary motions in a ferrocene-bridged diiron(III) porphyrin dimer

Abstract

In the present work, we have utilized ferrocene-bridged diiron(III) porphyrin dimer and investigate the rotary motions mediated by axial ligands exploiting conformational flexibility of the ferrocene linker. Diiron(III) porphyrin dimer can switch easily between the syn and anti rotamers reversibly based on the axial coordination and thereby forming complexes with different structure and properties for the development of synthetic molecular machines. While the five-coordinate diiron(III) complex with chloride axial ligand and its μ-oxo dimer are in syn-conformation, their six-coordinate complexes are stabilized in anti-conformation. All the complexes are isolated in the solid state and five-coordinate complexes are also structurally characterized. Spectroscopic investigation through UV–visible spectra, solid-state Mössbauer, EPR, and 1H NMR studies confirm the presence of high and low-spin diiron(III) porphyrins, respectively, for five and six-coordinate complexes.