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), L-TBo; -N{B(DipNCH)(2)}(SiPh3), L-PhBo; -N(Dip)(tBu), L-DBu; 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 ((LGe)-L-TBo-(GeL)-L-TBo and (LGe)-L-PhBo-(GeL)-L-PhBo), and an amido-distannyne ((LSn)-L-PhBo-(SnL)-L-PhBo), in addition to several low-valent, amido stabilized tetrel-tetrel bonded cluster compounds, ((LGe)-L-DBu)(4), ((LSn)-L-DBu)(6) and Sn-5(L-TBo)(4). The nature of the products resulting from these reactions was largely dependent on the steric bulk of the amide ligand employed. Cluster ((LGe)-L-DBu)(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, L-TBo(H)Ge=Ge(H)L-TBo and the cyclotetragermane, {L-DBu(H)Ge}(4). Reactions of ((LGe)-L-DBu)(4) with a series of unsaturated small molecule substrates yielded (LGeOGeL)-L-DBu-L-DBu, (LGe)-L-DBu(mu-C2H4)(2)(GeL)-L-DBu and (LGe)-L-DBu(mu-1,4-C6H8)(mu-1,2-C6H8)(GeL)-L-DBu. The latter results imply that ((LGe)-L-DBu)(4) can act as a masked source of the digermyne (LGeGeL)-L-DBu-L-DBu 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.