New concepts for the directed synthesis of functional free boroles and development of their coordination chemistry toward main group elements.

• Applicant: Professor Dr. Christian Sindlinger
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 496024290

The monoanionic Cp-ligand is a fundamental pillar of organometallic coordination chemistry. It forms stable compounds with almost all elements throughout the periodic table with great relevance ranging from fundamental research to materials and industrial catalysis. In many ways, the isoelectronic, dianionic boracyclopentadiene (borole) can be compared to the cyclopentadienyl, however the application of boroles in coordination chemistry has only been studied with regards to d-block elements. Boroles as ligands in p-block chemistry are almost or entirely unknown.The scope of this research project is the development of selective synthetic routes to novel free boroles of controlled reactivity and the corresponding dianions of these boroles to introduce and establish these compounds as versatile and robust ligands for the application in p- block chemistry. The key focus will be on developing a fundamental understanding of reaction conditions to access free boroles which will then enable the crucial extension of applicable substitution patterns for this class of heterocycles.In order to achieve this, we will systematically probe regioselective, metal-centred couplings of unsymmetrical acetylenes to generate new 1,4-dimetallabutadiene reagents to enable the selective synthesis of diversely substituted boroles. By substituent-based control of the electronic and/or steric profiles or by additional functional groups introduced into the system, the suitability of boroles as ligands will be systematically adjusted and optimised – ultimately laying grounds for an application-focussed design of borole ligands. Investigations into new, mild borole transfer reagents will enable further synthetic access routes with p-block precursors and pave way for an extension of their coordination chemistry. The structures, properties and reactivities of respectively accessed, yet unknown target compounds of main group element borolediides will be investigated and developed towards further applications by constant controlled adjustedment of the substituents. Fundamental knowledge of the synthesis of hand-tailored functional boroles and of effective synthetic protocols for p-block borolediides represents a huge potential for further developments in chemical applications, including catalytic or materials-oriented topics.

• DFG Programme: Research Grants