0369086 - ÚFCH JH 2012 RIV CH eng J - Journal Article
Mücke, P. - Zabel, M. - Edge, R. - Collison, D. - Clément, S. - Záliš, Stanislav - Winter, R. F.
Electron delocalization in vinyl ruthenium substituted cyclophanes: Assessment of the through-space and the through-bond pathways.
Journal of Organometallic Chemistry. Roč. 696, č. 20 (2011), s. 3186-3197. ISSN 0022-328X. E-ISSN 1872-8561
R&D Projects: GA MŠMT LD11086; GA AV ČR KAN100400702
Institutional research plan: CEZ:AV0Z40400503
Keywords : electrochemistry * vinyl complexes * ruthenium
Subject RIV: CG - Electrochemistry
Impact factor: 2.384, year: 2011
DOI: https://doi.org/10.1016/j.jorganchem.2011.06.028

Pseudo-para[2.2]paracyclophane- and [2.1]orthocyclophane-bridged diruthenium complexes 2 and 3 with two interlinked electroactive styryl ruthenium moieties have been prepared and investigated. Both complexes undergo two reversible consecutive one-electron oxidation processes which are separated by 270 or 105 mV. Stepwise electrolysis of the neutral complexes to first the mixed-valent radical cations and then the dioxidized dications under IR monitoring reveal incremental shifts of the charge-sensitive Ru(CO) bands and allow for an assignment of their radical cations as moderately or very weakly coupled mixed-valent systems of class II according to Robin and Day. Ground-state delocalization in the mixed-valent forms of these complexes as based on the CO band shifts is considerably larger for the "closed" paracyclophane as for the "half-open" orthocyclophane. Experimental findings are backed by the calculated IR band patterns and spin density distributions for radical cations of slightly simplified model complexes 2Me(.+) and 3Me(.+) with the P(i)Pr(3) ligands replaced by PMe(3). Radical cations 2(.+) and 3(.+) feature a characteristic NIR band that is neither present in their neutral or fully oxidized forms nor in the radical cation of the monoruthenium [2.2] paracyclophane complex 1 with just one vinyl ruthenium moiety. These bands are thus assigned as intervalence charge-transfer (IVCT) transitions. Our results indicate that, for the radical cations, electronic coupling "through-space" via the stacked styrene decks is significantly more efficient than the "through-bond" pathway.

Permanent Link: http://hdl.handle.net/11104/0203235