INTERMOLECULAR COMPLEXES OF GERMANIUM(II

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 111 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.

Name thesis:degree_name

Ph D

Discipline thesis:degree_discipline

Chemistry

Year dc:date.issued

2009

Author dc:creator

• Rupar, Paul A.

Advisor dc:contributor.advisor

• Baines, Kim

• germylene
• germanium(II)
• N-heterocyclic carbene
• base stabilized
• crystal structure
• crown ether
• cryptand
• gallium(I

Handle dc:identifier.uri

https://hdl.handle.net/20.500.14721/19495

OAI identifier oai:identifier

oai:uwo.scholaris.ca:20.500.14721/19495