Amphiphilicity in Oxygen Atom Transfer Reactions of Oxobis(iminoxolene)osmium Complexes.

Oxobis(iminoxolene)osmium(VI) compounds (ap)OsO (ap = 2-(4-RCHN)-4,6-BuCHO) are readily deoxygenated by phosphines and phosphites to give five-coordinate (ap)Os(PR') or six-coordinate (ap)Os(PR'). Structural data indicate that this net two-electron reduction is accompanied by apparent oxidation of the iminoxolene ligands due to their greater ability to engage in π donation to the reduced deoxy form of the osmium complex. In (ap)Os(PR'), the HOMO is a ligand-based combination of the iminoxolene redox-active orbitals, while the LUMO is a highly covalent metal-iminoxolene π* orbital.

High-valent osmium iminoxolene complexes.

2-(Arylamino)-4,6-di-tert-butylphenols containing 4-substituted phenyl groups (RapH2) react with oxobis(ethylene glycolato)osmium(vi) in acetone to give square pyramidal bis(amidophenoxide)oxoosmium(vi) complexes. A mono-amidophenoxide complex is observed as an intermediate in these reactions. Reactions in dichloromethane yield the diolate (Hap)2Os(OCH2CH2O).