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

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 beta-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 1(") 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) Ru-III-L-](3+) (1(3+)). [([9]aneS3)(dmso) Ru-III-L-](2+)/[([9] aneS3)(dmso) Ru-II-L-](2+) (1(2+)). [([9] aneS3)(dmso) Ru-II-L-](+) (1(+)). [([9]aneS3)( dmso) Ru-II-L-2-] (1). [([9] aneS3)(dmso) Ru-II-L3-](-)/[([9] aneS3)(dmso) RuI-L-2-](-)(1(-)).