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)

• Published in: Organometallics 1997-10, Vol.16 (21), p.4686-4695
• Main Authors: Aarnts, Maxim P, Hartl, František, Peelen, Karin, Stufkens, Derk J, Amatore, Christian, Verpeaux, Jean-Noël
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om9702800

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 closed-shell five-coordinate anions [Ru(E‘)(CO)2(iPr-DAB)]- via transient radicals [Ru(E‘)(CO)2(iPr-DAB)]•. In the final step of the overall ECEC sequence at room temperature the five-coordinate anions attack 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 arises from the strength of the delocalized axial E−Ru−E‘ bond. Subsequent reduction of [Ru(E‘)(CO)2(iPr-DAB)]2 and [Ru(E)(E‘)(CO)2(iPr-DAB)]•- ultimately yields [Ru(E‘)(CO)2(iPr-DAB)]-. Reverse oxidation of the anions directly results in the recovery of the parent complexes Ru(Cl)(E‘)(CO)2(iPr-DAB) and Ru(E)(E‘)(CO)2(iPr-DAB). Two different, 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‘ ≠ Cl) and [Ru(E‘)(CO)2(iPr-DAB)]- are discussed on the basis of their UV−vis, IR, NMR, EPR, and resonance Raman data.