Catalyst Activation with Cp*Rh^III/Ir^III–1,2,3-Triazole-Based Organochalcogen Ligand Complexes: Transfer Hydrogenation via Loss of Cp* and N-Methylmorpholine N-Oxide Based vs Oppenauer-Type Oxidation

The reactions of 1-benzyl-4-((phenylthio/phenylseleno)methyl)-1H-1,2,3-triazole (L1/L2) and 4-phenyl-1-((phenylthio/phenylseleno)methyl)-1H-1,2,3-triazole (L3/L4), synthesized using the click reaction, with [(η5-Cp*)RhCl(μ-Cl)]2 and [(η5-Cp*)IrCl(μ-Cl)]2 at room temperature followed by treatment with NH4PF6 result in complexes of the type [[(η5-Cp*)M(L)Cl] (1–8). Their HR-MS and 1H, 13C{1H}, and 77Se{1H} NMR spectra have been found characteristic. The single-crystal structures of 2, 3, and 6 have been established by X-ray crystallography. There is a pseudo-octahedral “piano-stool” disposition of donor atoms around Rh/Ir. In 1, 2, 5, and 6 N(3) of the triazole skeleton coordinates with Rh/Ir, whereas in the other four complexes the nitrogen involved is N(2). These complexes have been explored as catalysts for N-methylmorpholine N-oxide (NMO) based and Oppenauer-type oxidation of alcohols and transfer hydrogenation (TH) of carbonyl compounds with 2-propanol. Oppenauer type oxidation is somewhat slower than ...