Reactivity of Ytterbium(II) Hydride. Redox Reactions: Ytterbium(II) vs Hydrido Ligand. Metathesis of the Yb–H Bond

Oxidation reactions of the Yb(II) hydride [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-H)]2 (1) with CuCl (1:2 molar ratio) and (PhCH2S)2 (1:1 molar ratio) revealed that the hydrido anion in 1 is a stronger reductant than the Yb(II) cation. Both reactions occur with evolution of H2 and afford the dimeric Yb(II) species [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-X)]2 (X = Cl (2), SCH2Ph (3)) in which a κ1-amido,η6-arene type of coordination of amidinate ligand is retained. Reaction of 1 with 2 equiv of (PhCH2S)2 results in oxidation of both Yb(II) and hydrido centers and leads to the formation of the Yb(III) complex [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-SCH2Ph)2]2 (4). Complex 4 can be also synthesized by oxidation of 3 with an equimolar amount of (PhCH2S)2. It was demonstrated that oxidation of the ytterbium center to the trivalent state leads to switching of the coordination mode of amidinate ligand from κ1-amido, η6-arene to “classical” κ1,κ1-N,N-chelating. Unlike Yb(III) bis(alkyl) species supported by bulky amidopyridinate ligands, the rea...