Issue 12, 2001

Mononuclear and dinuclear ruthenium(II)/(III) salicylates incorporating azoimine functionalities as ancillary ligands. Synthesis, spectroscopic and electron-transfer properties

Abstract

Ruthenium–salicylate complexes incorporating azoimine based azopyridine ligands, L, of the type [RuII(L)2(salicylate)] 15 [L = NC5H4N[double bond, length as m-dash]NC6H4(R), R = H, m-Me/Cl or p-Me/Cl] have been synthesized and their spectroelectrochemical aspects investigated. The complexes systematically exhibit two 1e and two 2e oxidation processes and four successive one-electron reductions. The stepwise electrochemical oxidations were followed by electronic and EPR spectral studies on each oxidation step which indicate that the initial one-electron oxidation process corresponds to stereoretentive oxidation of the ruthenium(II) centre to ruthenium(III), [RuIII(L)2(salicylate)]+1++–5++. The second oxidation step corresponds to oxidation of the coordinated salicylate moiety in 1++–5++ to the ruthenium(III)–salicylate semiquinone cationic radical, [RuIII(L)2(salicylate)]2+E. The electrogenerated ruthenium(III) congeners (1++–5++) exhibit rhombic EPR spectra corresponding to distorted octahedral complexes. The electrogenerated semiquinone salicylate radical [RuIII(L)2(salicylate)]2+E undergoes a radical recombination process which leads to formation of antiferromagnetically coupled dimeric species, [(L)2RuIII(X)RuIII(L)2]4+F [(X = O2C(O)C6H4C6H4(O)CO2]. The next two 2e oxidation processes are associated with oxidation of the bridging moiety of the dimeric species [(L)2RuIII(X′)RuIII(L)2]4+G [(X′ = O2C(O)C6H3[double bond, length as m-dash]C6H3(O)CO2] followed by oxidation of the metal centres, [(L)2RuIV(X′)RuIV(L)2]6+H. The chemical oxidation of the complexes 15 by HNO3 leads to formation of dimeric complexes, G, straightaway. The complexes display intense charge-transfer bands in the UV-visible region which have been found to be reasonably blue shifted while moving from 15 to 1++–5++ to F to G.

Graphical abstract: Mononuclear and dinuclear ruthenium(II)/(III) salicylates incorporating azoimine functionalities as ancillary ligands. Synthesis, spectroscopic and electron-transfer properties [ ]

Supplementary files

Article information

Article type
Paper
Submitted
03 Jan 2001
Accepted
12 Apr 2001
First published
25 May 2001

J. Chem. Soc., Dalton Trans., 2001, 1827-1833

Mononuclear and dinuclear ruthenium(II)/(III) salicylates incorporating azoimine functionalities as ancillary ligands. Synthesis, spectroscopic and electron-transfer properties

R. Samanta, B. Mondal, P. Munshi and G. Kumar Lahiri, J. Chem. Soc., Dalton Trans., 2001, 1827 DOI: 10.1039/B100163I

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements