Synthesis, Reactivity and Catalysis of New Metallacarborane complexes

Carboranes, boranes and metallacarboranes have interesting structures and have been at the forefront of the development in new insights and fundamental understanding of bonding throughout chemistry.
This project is concerned with the synthesis and chemical properties of new early transition/lanthanide element and main group element metallacarboranes. This project will pursue studies in three specific areas; In the first of these studies we wish to develop main group carborane derivatives, with an emphasis on reactivity relationships aimed at a greater understanding of the chemistry of these unusual compounds. Of particular interest is the chemistry of novel group 13/14 main group element complexes, as well as exploration of potential applications of these and related carborane derivatives in catalysis. The second category of studies is focused on an effort to synthesize new high oxidation state early transition element and lanthanide element derivatives of the metallacarborane type, which bear subtle resemblance to known imido and cyclopentadienide complexes. Some of the new materials which will be synthesized are expected to have interesting physical properties possibly including desirable electronic and/or spectral properties, and some will be useful precursors for the synthesis of interesting materials.
Despite many of these systems having been known for some time, exploitation of this chemistry wrt the formation of metal amides, metal alkyls and metal hydrides is amazingly underdeveloped. Even starting form known materials we have the opportunity to develop remarkable complexes the reactivity of which has never been explored and is ripe for development. Figure 1 shows one possible route to the development of a Ti(IV) system incorporating a dicarboloide ligand and two amide groups this {Ti(dicarbollide)} fragment, or Cuckoo complex, has the potential to act as a surrogate earth abundant metal such as Ca and hopefully displaying similar reactivitys to real complexes such as Ca(HMDS)2 and Ca(CH{SiMe3}2)2, both of which have shown application in a range of catalytic applications including, but not limited to, polysilazane synthesis, catalytic hydroamination, and catalytic hydroboration. Hoverer unlike a naked Ca ion the metal dicarbollide fragment can be further tuned by augmentation of the B and c substituents on the coordinating face of the dicarbollide, such that stabilising groups which provide electron density to the system may be incorporated.
Thirdly, as part of our study we propose to investigate the use of heterometallic systems supported by the dicarbollide ligand. We will form bi-metallic complexes in which the exo-metal will display a synergistic effect on these complexes modifying their reactivity and enhancing activity, and just as the Ae element can be changed (group 13 & Ln elemental are also of interest) the group 1 metal can be changed from Li to Na, K, Rb etc. or non-coordinating cations such as PPN (Ph3P=N=PPh3).
The metal carborane clusters studied in this research may have potential applications in catalysis, and molecular electronics. The project incorporates a strong emphasis on synthesis, characterization of new complexes which align to a number of the strategic themes of the department/university and EPSRC, making it an excellent project for training students.