Multiply Lewis-acidic and metallophilic receptor systems with trisilacyclohexane skeletons

• Applicant: Professor Dr. Norbert W. Mitzel
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 313483887

Specific chemical functionality can be achieved by purposeful selection of functions and their defined spatial positioning. This principle is realized in nature in many ways, for example in enzymes and chemists use it when designing molecular catalysts. Typically, donor functions or hydrogen bridging units are made use of, while the arrangement of Lewis-acidic receptors is much less common. However, such an approach opens up the possibility for detecting and complexing anions or Lewis bases and thus to change their properties and reactivities. The aim of this project is the synthesis and utilization of new systems with multiple spatially aligned Lewis-acidic or metallophilic receptor functions. In previous work we have shown that trisilacyclohexane frameworks substituted with three alkyne groups represent a class of molecules that possess all prerequisites for the construction of the desired target systems: good preparative accessibility, absence of competing Lewis base functionalities and facile functionalization by a number of established reactions. In this project several classes of trialkyne-trisilacyclohexanes are to be terminally metalated with metal alkyls via alkane elimination reactions, or metal functions are to be added via hydrometalation reactions to the alkyne groups. In this way, groups like R2Al, Cl2Ga and R2Ga or electronegatively substituted boryl and silyl groups such as BR2 and SiR3 (R = F, Cl, C2F5, C6F5, C6F3(CF3)2, etc.) but also other metal atoms such as gold and mercury will be attached to the rigid frameworks. The former serve to construct molecular skeletons with the possibility of substrate recognition via Lewis acid-base interactions, the latter make use of dispersive driven d10-d10 interactions. The goal is to learn constructing tailor-made receptors and to use them for selective recognition and modification of chemical and physical properties of Lewis basic or metallophilic substrates. Further application aspects of this chemistry concern the examination of chelating Lewis acids in the chemistry of frustrated Lewis pairs and to try a new approach in designing super-Lewis-acids in the form of metal-adadamantane compounds with pyramidal coordination environments of their Group 13 elements.

• DFG Programme: Research Grants