Selective Metal‐Cation Recognition by [2.2]Ferrocenophanes: The Cases of Zinc‐ and Lithium‐Sensing

Abstract

The synthesis, electrochemical, optical, and cation-sensing properties of [2.2]ferrocenophanes, in which the two ferrocene subunits are linked through two aldiminic or iminophosphorane moieties, are reported. The new compounds show remarkably selective cation-sensing properties due to the presence of redox-active units (ferrocene) and aza-unsaturated functionalities that are able to act as putative cation-binding sites. In this structural motif, the aldimine groups act as a highly selective binding site for Zn(2+) cations, whereas the iminophosphorane bridges display an unusually strong binding affinity towards Li(+) cations, which could be explained by an additional LiFe interaction. The X-ray structure of the complex 4Li(+) as well as detailed NMR spectroscopic studies, both in solution and in the solid state, support this assessment. Experimental data and conclusions about the cation-sensing capabilities of this family of compounds are supported by DFT calculations.

Ferrocene-bis(phosphinimine) Nickel(II) and Palladium(II) Alkyl Complexes: Influence of the Fe–M (M = Ni and Pd) Interaction on Redox Activity and Olefin Coordination

“…However, the use of these complexes in redoxswitchable catalysis has not been investigated. For example, ferrocene-bis(phosphinimines) have been used as supporting ligands, 43,54 but not in catalytic examples. Based on our interest in redox-switchable catalysis utilizing ferrocene derivatives, we decided to prepare ferrocene-bis(phosphinimine) nickel and palladium alkyl complexes containing iron-nickel and iron-palladium interactions and investigate their efficacy for redoxswitchable olefin polymerization.…”

Spectroscopic Advances in Structural Lithium Chemistry: Diffusion‐Ordered Spectroscopy and Solid‐State NMR

“…Oton et al [84] have also used solution and solid-state NMR { 1 H, 13 C, 7 Li, and 31 P} to highlight the formation of a ferrocenophane (two ferrocene units bonded to the iminophosphorane)-lithium complex, isolated for the first time. They used solution-state NMR to study the conformational behavior of the compound.…”

Single step synthesis of an ethynylferrocenyl-[4]-ferrocenophane

“…For this reason, most of the employed syntheses of ferrocene-containing compounds start directly from the parent complex. Among the countless derivatives, ferrocenophanes have drawn particular attention for several applications in molecular recognition [4][5][6] and organometallic polymers. The presence of a ring-strained heteroannular bridge gives rise to new properties such as selective cation recognition 4 or precursor of conjugated polymers via ring-opening polymerization (ROP) 7 or ring-opening metathesis polymerization (ROMP).…”