Dihydroguaiazulenide Complexes and Catalysts of Group 8–12 Transition Metals: Ligands from Renewable Feedstock Replace, even Outmatch Petrochemical Based Cyclopentadienyl Chemistry

Abstract

We present an in‐depth study of the sterically demanding Cp synthon (8‐H‐GuaH)Li isolated from natural product guaiazulene as a ligand transfer reagent towards late transition metal complex precursors. The synthesis and full characterization of selected, essentially unexplored homo‐ and heteroleptic 8‐H‐guaiazulenide complexes of iron, ruthenium, cobalt, rhodium, platinum, copper and zinc are discussed in detail. In order to demonstrate their potential in catalytic applications, [(GuaH)PtMe3] was selected. The latter proved an even higher catalytic activity in light induced olefin hydrosilylation at catalyst loads as low as 5 ppm than classical [CpPtMe3] in a typical test reaction of silicone elastomer fabrication. Our results demonstrate that traditional petrochemical based Cp metal chemistry and catalysis can be replaced, sometimes even outmatched by superior catalysts based on cheap building blocks from renewable feedstock.

Organotransition Metal Chemistry of Terpenes: Syntheses, Structures, Reactivity and Molecular Rearrangements

“…Later studies established that this interconversion can also be induced photochemically, and the barrier to haptotropic migration was found to be 117 ± 8 kJ mol −1 [99]; in the ruthenium analogues, the barriers were found to be markedly higher [100]. In an excellent very recent publication, it was reported that hydrolithiation of guaiazulene yields the isomerically pure dihydroguaiazulenide anion, a stable and storable cyclopentadienide-type ligand ideally suited for reaction with a wide range of organometallic precursors [101]. A number of half-sandwich complexes shown in Figure 6, in particular the trimethylplatinum complex, exhibit excellent catalytic activity in alkene hydrosilylations.…”

“…A number of half-sandwich complexes shown in Figure 6, in particular the trimethylplatinum complex, exhibit excellent catalytic activity in alkene hydrosilylations. In an excellent very recent publication, it was reported that hydrolithiation of guaiazulene yields the isomerically pure dihydroguaiazulenide anion, a stable and storable cyclopentadienide-type ligand ideally suited for reaction with a wide range of organometallic precursors [101]. A number of half-sandwich complexes shown in Figure 6, in particular the trimethylplatinum complex, exhibit excellent catalytic activity in alkene hydrosilylations.…”