Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles

Abstract

Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double-decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [Tb (tpp) ] (tpp: tetraphenylporphyrinato, n=-1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [Tb (oep) ] and [Tb (oep) ] (oep: octaethylporphyrinato), but φ=36° for [Tb (oep) ] . Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system.

Highly Oxidized States of Phthalocyaninato Terbium(III) Multiple‐Decker Complexes Showing Structural Deformations, Biradical Properties and Decreases in Magnetic Anisotropy

“…More recently, Yamashita et al. have observed structural changes in Por double‐decker complexes induced by ligand oxidation using single‐crystal X‐ray (SXRD) measurements and have shown that ligand oxidation induces axial compression, which has been supported by theoretical calculations . Moreover, the axial compression in Pc double‐decker complexes induced by oxidation has been investigated by using solution NMR spectroscopy .…”

“…[27][28][29][30] More recently,Y amashita et al have observed structural changes in Pord ouble-decker complexes induced by ligand oxidation using single-crystal Xray (SXRD) measurements and have shown that ligand oxidation induces axial compression, which has been supported by theoretical calculations. [31] Moreover, the axial compression in Pc double-decker complexes induced by oxidation has been investigated by using solutionN MR spectroscopy. [32] The conformational changes, especially ligand rotation,i nd oubledecker complexes have been directly observed [33,34] and controlled using as canning electron microscope (STM) and scanning electron spectroscopy (STS).…”

Lanthanide–tetrapyrrole complexes: synthesis, redox chemistry, photophysical properties, and photonic applications

“…The eight ethyl groups on the porphyrin macrocycle of H 2 OEP seem to have a much smaller steric effect since the f angle is equal to 451 for n = À1 and 0 and decreases to only 361 for n = +1. 254 In the series [Ln(Nc)(TBPP)], where H 2 TBPP is meso-tetra(4-tbutylphenyl)porphyrin, three quasi-reversible, one-electron oxidation and one reduction steps are revealed by cyclic voltammetry in methylene chloride at ambient temperature. 166 A second reduction could not be detected owing to solvent breakdown.…”

Stable Singlet Biradicals of Rare‐Earth‐Fused Diporphyrin‐Triple‐Decker Complexes with Low Energy Gaps and Multi‐Redox States

“…The anionic complex 2 shows a near square antiprism (SAP) coordination, having ϕ of 41° (Figure b), whereas 1 and 3 have distorted SAP structures with smaller ϕ (33° and 40°) (Figures a and 2c). This dependence of the ϕ on the chemical states of the complexes is similar to those of previously reported Tb(TPP) 2 complexes, which indicates the validity of the structural identification ,…”

“…Monoradical [(TPP)Tb(TPP)] . shows near IR (1340 nm) absorption because of the promotion of an electron from a filled bonding orbital to the half‐filled anti‐bonding orbital ,. In 1 and 1′ , probably because of the combination of the similar electron promotion with a larger delocalization of the π‐electron of FP, an IR optical energy gap is formed.…”