STUDIES ON SOME MIXED-LIGAND COMPLEXES OF RUTHENIUM(II) INVOLVING DITHIOCARBOXYLATES, DITHIOCARBAMATES, TRIPHENYLPHOSPHINE AND BIPYRIDINE

Ruthenium(II) complexes [Ru(R-acda)(2)(PPh(3))(2)] (1a-e), [Ru(R-acda) (bpy)(2)](ClO4)(2a-d), [Ru(R-acda)(phen)(2)]ClO4) (2e-g), [Ru(R(2)-dtc )(bpy)(2)] (ClO4) (3a, b) and [Ru(R(2)-dtc) (phen)(2)]ClO4)(3c, d) (wh ere R-acdaH = 2-alkylamino-1-cyclopentene-1-dithicarboxylic acid, R(2) -dtcNa = sodium N,N'-dialkyl dithiocarbamate, bpy = 2,2'-bipyridine an d phen = 1,10-phenanthroline) have been synthesized and characterized. The H-1 NMR spectra of the phosphine complexes (1a-e) show that, with the increase in the chain length of the alkyl group of R-acda(-), the N-alkylamino proton becomes more deshielded and is accompanied by a s hift of the NH stretching frequency v(NH) to lower energy. A linear re lationship is obtained between the chemical shift delta(NH) and v(NH). All the complexes exhibit absorption bands due to d pi --> pi (bpy, phen or PPh(3)), d pi --> pi (R-acda(-) or R(2)-dtc(-)) charge transf er transitions and pi --> pi intraligand transition. Complexes 1a-e u ndergo two irreversible oxidations, Ru-II --> Ru-III and Ru-III --> Ru -IV, while the other complexes (2, 3) exhibit one reversible (Ru-II/Ru -III) and one irreversible (Ru-III --> Ru-IV) oxidation process. Copyr ight (C) 1996 Elsevier Science Ltd