Bidirectional non-innocence of the β-diketonato ligand 9-oxidophenalenone (L-) in [Ru([9]aneS3)(L)(dmso)]n, [9]aneS3 = 1,4,7-trithiacyclononane

Abstract

The new compound [RuII([9]aneS3)(L)(dmso)]ClO4 ([1]ClO4) ([9]aneS3 = 1,4,7-trithiacyclononane, HL = 9-hydroxyphenalenone, dmso = dimethylsulfoxide) has been structurally characterised to reveal almost equal C-O bond distances of coordinated L -, suggesting a delocalised bonding situation of the β-diketonato ligand. The dmso ligand is coordinated via the sulfur atom in the native (1+) and reduced states (1 and 1-) as has been revealed by X-ray crystallography and by DFT calculations. Cyclic voltammetry of 1+ exhibits two close-lying one-electron oxidation waves at 0.77 V and 0.94 V, and two similarly close one-electron reduction processes at -1.43 V and -1.56 V versus SCE in CH2Cl2. The electronic structures of 1n in the accessible redox states have been analysed via experiments (EPR and UV-vis-NIR spectroelectrochemistry) and by DFT/TD-DFT calculations, revealing the potential for bidirectional non-innocent behaviour of coordinated L/-/2-. Specifically, the studies establish significant involvement of L based frontier orbitals in both the oxidation and reduction processes: [([9]aneS3)(dmso)RuIII-L]3+ (1 3+) [([9]aneS3)(dmso)RuIII-L-] 2+/[([9]aneS3)(dmso)RuII-L]2+ (12+) [([9]aneS3)(dmso)RuII-L-]+ (1+) [([9]aneS3)(dmso)RuII-L2-] (1) [([9]aneS3)(dmso)Ru II-L3-]-/[([9]aneS3)(dmso)RuI-L 2-]- (1-). © 2014 The Royal Society of Chemistry.