A “pretender” croconate-bridged macrocyclic tetraruthenium complex: Sizable redox potential splittings despite electronically insulated divinylphenylene diruthenium entities

Rotthowe N, Linseis M, Vogelsang L, Orth N, Ivanovic-Burmazovic I, Winter RF (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Molecules MDPI

Book Volume: 26

Article Number: 5232

Journal Issue: 17

DOI: 10.3390/molecules26175232

Abstract

Careful optimization of the reaction conditions provided access to the particularly small tetraruthenium macrocycle2 Ru2Ph-Croc, which is composed out of two redox-active divinylphenylene-bridged diruthenium entities {Ru}-1,4-CH=CH-C6H4-CH=CH-{Ru} (Ru2Ph; {Ru} = Ru(CO)Cl(PⁱPr3)2) and two likewise redox-active and potentially non-innocent croconate linkers. According to single X-ray diffraction analysis, the central cavity of²Ru2Ph-Croc is shielded by the bulky PⁱPr3 ligands, which come into close contact. Cyclic voltammetry revealed two pairs of split anodic waves in the weakly ion pairing CH2Cl2/NBu4BAr^F24 (BAr^F24 = [B{C6H3(CF3)2-3,5}4]-electrolyte, while the third and fourth waves fall together in CH2Cl2 / NBu4PF6. The various oxidized forms were electrogenerated and scrutinized by IR and UV/Vis/NIR spectroscopy. This allowed us to assign the individual oxidations to the metal-organic Ru2Ph entities within²Ru2Ph-Croc, while the croconate ligands remain largely uninvolved. The lack of specific NIR bands that could be assigned to intervalence charge transfer (IVCT) in the mono-and trications indicates that these mixed-valent species are strictly charge-localized.²Ru2Ph-Croc is hence an exemplary case, where stepwise IR band shifts and quite sizable redox splittings between consecutive one-electron oxidations would, on first sight, point to electronic coupling, but are exclusively due to electrostatic and inductive effects. This makes²Ru2Ph-Croc a true “pretender”.

Authors with CRIS profile

Nicole Orth Lehrstuhl für Bioanorganische Chemie Ivana Ivanovic-Burmazovic Lehrstuhl für Bioanorganische Chemie

Involved external institutions

Universität Konstanz

Germany (DE)

How to cite

APA:

Rotthowe, N., Linseis, M., Vogelsang, L., Orth, N., Ivanovic-Burmazovic, I., & Winter, R.F. (2021). A “pretender” croconate-bridged macrocyclic tetraruthenium complex: Sizable redox potential splittings despite electronically insulated divinylphenylene diruthenium entities. Molecules, 26(17). https://dx.doi.org/10.3390/molecules26175232

MLA:

Rotthowe, Nils, et al. "A “pretender” croconate-bridged macrocyclic tetraruthenium complex: Sizable redox potential splittings despite electronically insulated divinylphenylene diruthenium entities." Molecules 26.17 (2021).

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