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Issue 24, 2017
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An extended π-system and enhanced electronic delocalization on symmetric [Ru3O(CH3COO)6(L)3]n complexes combined with azanaphthalene ligands

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Abstract

We report on the investigation of a new series of symmetric trinuclear ruthenium complexes combined with azanaphthalene ligands: [Ru3O(CH3COO)6(L)3]PF6 where L = (1) quinazoline (qui), (2) 5-nitroisoquinoline (5-nitroiq), (3) 5-bromoisoquinoline (5-briq), (4) isoquinoline (iq), (5) 5-aminoisoquinoline (5-amiq), and (6) 5,6,7,8-tetrahydroisoquinoline (thiq). The crystal structure of complex 1, [Ru3O(CH3COO)6(qui)3]PF6, was determined by X-ray diffraction analysis, showing a high degree of co-planarity between the [Ru3O] plane and the azanaphthalene ligands. Spectroscopic (UV-visible, NMR and infra-red) and electrochemical (cyclic voltammetry and spectroelectrochemistry) data showed correlation with the pKa values of the azanaphthalene ligands and this dependence was rationalized in terms of the molecular orbital of the [Ru3O] unit and the structure of the ligands. By analysing the spectroscopic and electrochemical correlations, the ability of the azanaphthalene ligands to extend the electronic π-system of the [Ru3O] unit to the periphery of the compounds was demonstrated. This electronic effect accounts for the planarity of the structure of complex 1. It was also shown through molecular modeling results that, to explain the spectroscopic and electrochemical behaviour of these species, it is not possible to neglect the electronic mixing between the metallic and the acetate orbitals. Finally, this work revealed that electronic coupling is more pronounced in the azanaphthalene series of complexes than in pyridinic analogues and it is this coupling that determines the spectroscopic and electrochemical behaviour of the new species.

Graphical abstract: An extended π-system and enhanced electronic delocalization on symmetric [Ru3O(CH3COO)6(L)3]n complexes combined with azanaphthalene ligands

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Publication details

The article was received on 30 Mar 2017, accepted on 25 May 2017 and first published on 25 May 2017


Article type: Paper
DOI: 10.1039/C7DT01152K
Citation: Dalton Trans., 2017,46, 7926-7938
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    An extended π-system and enhanced electronic delocalization on symmetric [Ru3O(CH3COO)6(L)3]n complexes combined with azanaphthalene ligands

    B. Possato, V. M. Deflon, Z. Naal, A. L. B. Formiga and S. Nikolaou, Dalton Trans., 2017, 46, 7926
    DOI: 10.1039/C7DT01152K

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