47-Electron Organometallic Clusters Derived by Chemical and Electrochemical Oxidation of Trihydrido(alkylidyne)triruthenium and -triosmium Clusters. Ligand Additivity in Metal Clusters

Abstract

Cyclic voltammograms for H3Ru3(μ3-CX)(CO)9-nLn (X = OMe, SEt, Me, Et, Ph, NMeBz, Br; L = PR3, AsPh3, SbPh3; n = 2, 3), H3Ru3(μ3-COMe)(CO)6(PPh3)2(L) (L = P(OMe)3, CNCH2Ph), and H3Os3(μ3-COMe)(CO)7(PPh3)2 each display a quasi-reversible to reversible, one-electron oxidation followed by an irreversible to quasi-reversible, one-electron oxidation. The ligand and substituent effects upon the oxidation potential are analyzed as an example of ligand additivity in a cluster system; the oxidation potential of the alkylidyne cluster core is as sensitive to π-donor substituent effects as are aromatic π complexes such as CpFe(C5H4X) to substituents on the rings, and the dependence of the oxidation potential of the cluster upon ligand substitution on any given Ru atom is 37% of that expected for the oxidation of a monometallic complex. Reactions with 1 equiv of Ag+ or ferricenium give the 47-electron cations [H3Ru3(CX)(CO)6L3]1+ (X = OMe; L3 = (PPh3)2L‘; L‘ = CO, PPh3, P(OMe)3, CNCH2Ph; X = Ph, NMeBz, SEt, L = PPh3),...