Paul A. Rupar

Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Kim Baines


This thesis examines the synthesis, structural characterization, and reactivity of neutral and charged intermolecular donor complexes of germanium(II).

Base stabilized complexes of dimesitylgermylene (Mes2Ge) (mes = mesityl = 2,4,6- trimethylphenyl) with either an anionic diisopropylphenyl-substituted N-heterocyclic gallium® (NHGa') ligand or a diisopropyl substituted N-heterocyclic carbene (NHC) ligand were synthesized by the addition of two equivalents of either NHGa' or NHC to tetramesityldigermene (Mes2Ge=GeMes2). The complexes [NHGa-GeMes2] and NHC- GeMes2 are the first two examples of a transient germylene (Mes2Ge) being stabilized by intermolecular donors.

A series of NHC complexes of GefG (R = F, Cl, Br, I, CI/O3SCF3,0'Bu, NCS, Mes) were synthesized. The !H NMR spectra of the NHC-GeR2 complexes show broad signals at room temperature which was rationalized by either conformational interchanges or intermolecular exchanges. The NHC-GeR2 complexes were also examinedcomputationally. Theenergyofcomplexationwasfoundtodecreaseif7T

donor atoms are located adjacent to the germanium centre. The reactivity of selected NHC-GeR2 (R = Cl, OlBu, or Mes) complexes towards

2,3-dimethylbutadiene, S^-di-Wtyl-orthoquinone, methyl iodide, pivalic acid and benzophenone was examined. In comparison with uncomplexed GeR2 species, the NHC-GeR2 complexes are less reactive. The prospect of using the NHC-GeR2 complexes as a synthon for GeR2 appears to be reaction specific.

Finally, a series of cationic germanium(II) complexes were synthesized and characterized, including examples of germanium(II) centred dications. A germanium


centred dication supported by three NHC ligands [NHC3Ge][I]2 was characterized and examined computationally. The structure of (cryptand[2.2.2]Ge) , as the inflate salt, was reported and is the first example of a non-metal cation situated within a cryptand. A number cationic germanium crown ether complexes were are also synthesized including [[12]crown-4)2*Ge]2+, [[15]crown-5*GeOTf]+ and [benzo[15]crown-5•GeC1]+ and [benzo[15]crown-5•GeOTf. The geometries of the crown ether-germanium complexes were found to be highly dependent on the size of the crown ether and the substituent located on the germanium.



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