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 }(SiMe3 ), TBo L; -N{B(DipNCH)2 }(SiPh3 ), PhBo L; -N(Dip)(tBu), DBu L; Dip=C6 H3 iPr2 -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-GeTBo L and PhBo LGe-GePhBo L), and an amido-distannyne (PhBo LSn-SnPhBo L), in addition to several low-valent, amido stabilized tetrel-tetrel bonded cluster compounds, (DBu LGe)4 , (DBu LSn)6 and Sn5 (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 H2 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 LGeOGeDBu L, DBu LGe(μ-C2 H4 )2 GeDBu L and DBu LGe(μ-1,4-C6 H8 )(μ-1,2-C6 H8 )GeDBu L. The latter results imply that (DBu LGe)4 can act as a masked source of the digermyne DBu LGeGeDBu 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.