Synthesis and Reactivity Studies of Amido-Substituted Germanium(I)/Tin(I) Dimers and Clusters

Three amide ligands of varying steric bulk and electronic properties were utilized to prepare a series of amido-germanium(II)/tin(II) halide compounds, (LEX) _n , (L= -N{B(DipNCH) ₂ }(SiMe ₃ ), ^TBo L; -N{B(DipNCH) ₂ }(SiPh ₃ ), ^PhBo L; -N(Dip)(tBu), ^DBu L; Dip=C ₆ H ₃ iPr ₂ -2,6; E=Ge or Sn; X=Cl or Br; n=1 or 2). Reductions of these with a magnesium(I) dimer, {( ^Mes Nacnac)Mg} ₂ ( ^Mes Nacnac=[(MesNCMe) ₂ CH] ⁻ , Mes=mesityl), afforded singly bonded amido-digermynes ( ^TBo LGe−Ge ^TBo L and ^PhBo LGe−Ge ^PhBo L), and an amido-distannyne ( ^PhBo LSn−Sn ^PhBo L), in addition to several low-valent, amido stabilized tetrel–tetrel bonded cluster compounds, ( ^DBu LGe) ₄ , ( ^DBu LSn) ₆ and Sn ₅ ( ^TBo L) ₄ . The nature of the products resulting from these reactions was largely dependent on the steric bulk of the amide ligand employed. Cluster ( ^DBu LGe) ₄ possessed an unusual folded butterfly structure, the bonding and electronic of which were examined using DFT calculations. Reactions of the amido-germanium(I) compounds with H ₂ were explored, and gave rise to the amido-digermene, ^TBo L(H)Ge=Ge(H) ^TBo L and the cyclotetragermane, { ^DBu L(H)Ge} ₄ . Reactions of ( ^DBu LGe) ₄ with a series of unsaturated small molecule substrates yielded ^DBu LGeOGe ^DBu L, ^DBu LGe(μ-C ₂ H ₄ ) ₂ Ge ^DBu L and ^DBu LGe(μ-1,4-C ₆ H ₈ )(μ-1,2-C ₆ H ₈ )Ge ^DBu L. The latter results imply that ( ^DBu LGe) ₄ can act as a masked source of the digermyne ^DBu LGeGe ^DBu L in these reactions. All further reactivity studies indicated that the germanium(I) compounds exhibit a “transition-metal-like” behavior, which is closely related to that previously described for bulky digermynes and related compounds.