The development of organometallic complexes capable of promoting bifunctional catalysis through hydrogen bonding, proton abstraction or activation of non polar bonds is fundamental to our research group, aiming to novel reactivity. This may be achieved with nitrogen donor ligands, such as triazenes functionalized with N-heterocyclic as pyrazol. We have reported that a triazenide ligand functionalized with pyrazole reacted with [MCl2Cp*]2 [M = Rh(III), Ir(III)] and [RuCl2(p-cymene)]2 in acetonitrile at room temperature to generate the mononuclear complexes 2a-3. The catalytic activity of complex 2a in the transfer hydrogenation of chalcone and 5-hexen-2-one was enhanced at higher temperatures in the absence of base. In this direction other substrates as cinnamaldehyde and 6-methyl-5-hepten-2-one have been also evaluated with interesting results. We have found that in the absence of base complex 2a in addition to hydrogenation of the olefin and the carbonyl of aldehydes, also performs a Fisher coupling with the hydrogen source. Heptenone was also tested with less promising results.

Base-free transfer hydrogenation of alkenones with organometallic complexes bearing a triazenide ligand functionalized with pyrazole

255th National Meeting (2018)

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