Catalytic ways to new inorganic polymers: development of transition metal catalysts for highly selective dehydropolymerisation of amine boranes

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The field of so-called inorganic polymers has seen significant advances in recent years. Poly(aminoborane)s as inorganic analogues of ubiquitous polyolefins represent examples for compounds of this type, possessing a polymer main chain that exclusively contains boron and nitrogen. These structures are of fundamental and application-oriented interest in the context of BN/CC isosterism and as pre-ceramics for new B-N containing materials. Modification of the amine borane precursor itself, the poly(aminoborane), or the reactions conditions used for the synthesis of heterogeneous materials (i.e., temperature, atmosphere, metal dopants) could open new avenues in the chemistry of main group materials, including applications in heterogeneous catalysis. Within the framework of this project, the knowledge gained in the previous project on the catalytic dehydropolymerisation of methylamine-borane is to be extended to new catalysts based on group 9 metals. Previous investigations showed that mainly rhodium complexes as well as complexes with pincer ligands catalyse this reaction with high selectivity for the desired polymer. In the investigations now proposed, this approach is to be systematically pursued further and extended to include the use of pincer ligands with a modifiable secondary coordination sphere for metal-ligand cooperative binding, activation, dehydrogenation, and coupling of amine boranes. We will furthermore evaluate possibilities to replace phosphine-based ligands. The presented project will contribute to the mechanistic understanding of the reaction as well as to the development of new catalysts for the selective dehydropolymerisation of primary amine boranes. Furthermore, the possibility of synthesising poly(aminoboranes) on a large scale for use as precursors for new, modifiable B-N materials will be investigated.