SPECTROELECTROCHEMICAL (UV-VIS, IR, NMR, AND EPR) STUDY OF THE INORGANOMETALLIC COMPLEXES RU(E)(E')(CO)(2)(IPR-DAB) (E = CL, E' = SNPH3, PBPH3, E = ME, SNPH3, GEPH3, E' = SNPH3 E = E' = PBPH3, IPR-DAB = 1,4-DIISOPROPYL-1,4-DIAZA-1,3-BUTADIENE)

The reduction paths of two series of inorganometallic Ru complexes, Ru (Cl)(E')(CO)(2)(iPr-DAB) (E' = SnPh3, PbPh3) and Ru(E)(E')(CO)(2)(iPr- DAB) (E = Me, GePh3, SnPh3, E' = SnPh3; E = E' = PbPh3), were studied by a series of spectroelectrochemical techniques. Reduction of the Cl complexes is a two-electron ECE process which directly affords the clo sed-shell five-coordinate anions [Ru(E')(CO)(2)(iPr-DAB)](-) via trans ient radicals [Ru(E')(CO)(2)(iPr-DAB)](.). In the final step of the ov erall ECEC sequence at room temperature the five-coordinate anions att ack the parent complexes, producing the dimers [Ru(E')(CO)(2)(iPr-DAB) ](2). In contrast, the non-halide complexes are reversibly reduced to the radical anions [Ru(E)(E')(CO)(2)(iPr-DAB)](.-) whose stability ari ses from the strength of the delocalized axial E-Ru-E' bond. Subsequen t reduction of [Ru(E')(CO)(2)(iPr-DAB)](2) and [Ru(E)(E')(CO)(2)(iPr-D AB)](.-) ultimately yields [Ru(E')(CO)(2)(iPr-DAB)](-). Reverse oxidat ion of the anions directly results in the recovery of the parent compl exes Ru(Cl)(E')(CO)(2)(iPr-DAB) and Ru(E)(E')(CO)(2)(iPr-DAB). Two dif ferent, temperature-controlled mechanisms operate during the oxidation of the Cl complexes. The electronic and geometric structures of [Ru(E )(E')(CO)(2)(iPr-DAB)](.-) (E, E' not equal Cl) and [Ru(E')(CO)(2)(iPr -DAB)](-) are discussed on the basis of their UV-vis, IR, NMR, EPR, an d resonance Raman data.