| Abstract
| - Synthesis starting from the complex [Ru(pdto)Cl(PPh3)]Cl, characterization, spectroelectrochemical, and electrochemical studies of the [Ru(pdto)Ln]Cl2 obtained were performed; Ln = 4,7-diphenyl-1,10-phenanthroline (L1), 1,10-phenanthroline (L2), 5,6-dimethyl-1,10-phenanthroline (L3), 4,7-dimethyl-1,10-phenanthroline (L4), and 3,4,7,8-tetramethyl-1,10-phenanthroline (L5). The crystal structure of the molecule [Ru(pdto)L2]Cl2 was obtained by X-ray diffraction. Electrochemical correlations were obtained.
- Reaction of dichlorotris(triphenylphosphine) ruthenium(II) [RuCl2(PPh3)3] with 1,8-bis(2-pyridyl)-3,6-dithiaoctane (pdto),a (N2S2) tetradentate donor, yields a new compound [Ru(pdto)(PPh3)Cl]Cl (1), which has been fully characterized.1H and 31P NMR studies of 1 in acetonitrile at several temperatures show the substitution of both coordinatedchloride and triphenylphosphine with two molecules of acetonitrile, as confirmed by the isolation of the complex[Ru(pdto)(CH3CN)2]Cl2 (2). Cyclic voltammetric and spectroelectrochemical techniques allowed us to determine theelectrochemical behavior of compound 1. The substitution of the chloride and triphenylphosphine by acetonitrilemolecules in the Ru(II) coordination sphere of compound 1 was also established by electrochemical studies. Theeasy substitution of this complex led us to use it as starting material to synthesize the substituted phenanthrolinecoordination compounds with (pdto) and ruthenium(II), [Ru(pdto)(4,7-diphenyl-1,10-phenanthroline)]Cl2·4H2O (3),[Ru(pdto)(1,10-phenanthroline)]Cl2·5H2O (4), [Ru(pdto)(5,6-dimethyl-1,10-phenanthroline)]Cl2·5H2O (5), [Ru(pdto)(4,7-dimethyl-1,10-phenanthroline)]Cl2·3H2O (6), and [Ru(pdto)(3,4,7,8-tetramethyl-1,10-phenanthroline)]Cl2·4H2O(7). These compounds were fully characterized, and the crystal structure of 4 was obtained. Cyclic voltammetricand spectroelectrochemical techniques allowed us to determine their electrochemical behavior. The electrochemicaloxidation processes in these compounds are related to the oxidation of ionic chlorides, and to the reversibletransformation from Ru(II) to Ru(III). On the other hand, a single reduction process is associated to the reductionof the substituted phenanthroline in the coordination compound. The E1/2 (phen/phen-) and E1/2 (RuII/RuIII) for thecompounds (3−7) were evaluated, and, as expected, the modification of the substituted 1,10-phenanthrolines inthe complexes also modifies the redox potentials. Correlations of both electrochemical potentials with pKa of thefree 1,10-phenathrolines, λmax MLCT transition band, and chemical shifts of phenanthrolines in these complexeswere found, possibly as a consequence of the change in the electron density of the Ru(II) and the coordinatedphenanthroline.
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