Unsolvated dimeric organometallic samarium hydride versus solvated trisalkylborane supported monomeric hydride

The dimeric hydride [Cp′₂SmH]₂ and the monomeric trisalkylborohydride Cp′₂SmHBEt₃(THF)_n (Cp′ = C₅H₄tBu) are obtained from the starting dimeric chloride [Cp′₂SmCl]₂ by reaction with a hydridic reagent: NaHBEt₃. By hydrogenolysis of Cp′₂SmR (R = CH₂SiMe₃ or CH(SiMe₃)₂) in the presence of an ancillary ligand as PMe₃, a monomeric hydride: Cp′₂SmH(PMe₃)₂ is formed. The trisalkylborohydride is fairly stable in solution when other new hydrides are only moderately stable: upon standing at room temperature, an irreversible transformation into Cp′₃Sm is observed. All hydrides react with propanone to give the corresponding alkoxide: [Cp′₂SmOCHMe₂]₂. The new alkyl complex [Cp′₂SmMe]₂ is isolated and characterized by NMR and elemental analysis. After hydrogenolysis of this dimer or by reaction of one equivalent of NaHBEt₃ with the dimer [Cp′₂SmCl]₂, mixed bridged hydrides of the general formula Cp′₂Sm(μ-H)(μ-X)SmCp′₂ (X = Me or Cl) are formed. A mixed bridged chloroalkoxy complex Cp′₂Sm(μ-OCHR₂)(μ-Cl)SmCp′₂ is also obtained.