Reductive elimination with main-group element compounds: From trihydrides to hydrides

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Reductive elimination with main-group element compounds: From trihydrides to hydrides The reductive elimination is an important reaction in metal organic chemistry. In this project we want to study the reductive elimination of hydrogen from germanium and tin compounds and elaborate this reaction towards the synthesis of new molecules. Through the reaction of Lewis bases like trialkylamines, substituted pyridines or N-heterocyclic carbenes with alkyl or aryl substituted trihydrides (R-EH3, E = Ge, Sn) we synthesize hydrides of divalent germanium and tin [(R-E-H)n] and carbene adducts [R-E-H(L)] thereof. Variation of the stoichiometric ratio of the N-heterocyclic carbene offers the possibility to isolate low valent clusters of type [(RE)n]. Because trihydrides are also known for substituents with less steric demand we aim on studying the steric influence of the substituent on the reactivity of the divalent hydrides and the size of the low valent clusters. In order to explore the reactivity of the hydrides and their carbene adducts, oxidative additions with for example boranes or silanes will be studied. The reactivity of the E-H bond will be investigated in reactions with unsaturated molecules like alkynes or ketones. Since divalent tin hydrides carrying sterically demanding substituents are known to catalyze the hydroboration of aldehydes and ketones, we will investigate the catalytic abilities of the synthesized hydrides of germanium and tin in hydroboration or hydrosilylation reactions. Finally, the coordination chemistry of the divalent hydrides is explored. Donor and acceptor properties of the hydridoylenes are investigated and the conditions for the alpha-elimination of the coordinated element hydride are studied.