Zintl ions as molecular analogues of liquid alloys for C–H activation

Thesis

This thesis describes the reactivity of the tris-hypersilyl substituted nonagermanide Zintl cluster [KGe9(Hyp)3] (Hyp = Si(SiMe3)3) towards group 9 and 10 transition metal organometallic complexes. The resulting Zintl clusters were then modified and tested in catalysis as molecular models for transition metal–main group element alloys (TMMGAs).

Firstly, nickel germanide clusters were synthesised, which were formed by vertex addition or substitution chemistry and further studied using cyclic voltammetry.

Next, the rhodium germanide cluster [Rh(COD){Ge9(Hyp)3}] (COD = 1,5-cyclooctadiene) was targeted in order to prepare a reactive metal alkene complex on the [Ge9(Hyp)3] support. This was then used as the first Zintl cluster based homogeneous catalyst in catalytic alkene hydrogenation.

This cluster was then modified by ligand substitution at the rhodium centre to produce highly fluctional clusters with the general formula [Rh(L){Ge9(Hyp)3}] (L = C2Me2, DPPE, PMe3, PPh3, IMe4, (Cp)2WH2). These were studied in catalytic processes which involve H–H and C–H bond activation.

Finally, [Rh(COD){Ge9(Hyp)3}] was modified by the addition of group 9 and 10 metal alkene fragments to the germanium support, showing that the cluster can be controllably expanded towards homo- and hetero-multimetallic clusters.

Authors: Townrow, OPE

• DOI: 10.5287/ora-bemn1rzdn
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Zintl; rhodium; catalysis; nickel; inorganic; organometallics; xluster
• Subjects: Catalysis; Organometallics; Inorganic Chemistry