Coordination chemistry of neutral quinolyl- and aminophenylcyclopentadiene derivatives

Role of Ligand Protonation in Dihydrogen Evolution from a Pentamethylcyclopentadienyl Rhodium Catalyst

“…The observation of a catalytically competent η 4 -Cp*H complex in this work contradicts the usual notion from organometallic chemistry that [η 5 -Cp*] is a spectator ancillary ligand in catalytic systems; instead, close metal–ligand cooperation appears to be involved in effective catalysis here. − Importantly, Cp*H has been demonstrated in previous work to serve as a ligand in several classes of transition-metal complexes. − However, involvement of [Cp*H] in hydrogen evolution catalysis was not previously postulated for this system . Considering the high activity of [Cp*] metal complexes in a number of important catalytic systems , as well as recent results by Peters and co-workers demonstrating a possible role for [Cp*H] moieties as H + /e – donors in N 2 reduction catalysis, an understanding of the role of [Cp*H] in hydrogen evolution with 1 could lead to better catalysts that exploit noninnocent reactivity modes of [Cp*] .…”

Proton–hydride tautomerism in hydrogen evolution catalysis

“…In other relevant work, Jones et al (20) showed that the dihydride complex Cp*Rh(PMe 3 )(H) 2 loses free Cp*H on treatment with excess PMe 3 at elevated temperature. Also, several other rhodium and iron complexes with Cp*H ligands are known (21)(22)(23)(24)(25).…”

New Chromium(III) Complexes as Highly Active Catalysts for Olefin Polymerization

“…The synthesis of the novel chromium complexes is straightforward. The ligands 1 − 4 were obtained in a one-step preparation and subsequent deprotonation of the corresponding cyclopentadiene derivatives with potassium hydride ( 1 , 2 , 4 ) or n -butyllithium ( 3 ), respectively . Reaction of 1 − 4 with CrCl 3 (THF) 3 leads to the half-sandwich compounds 5 − 8 , which were isolated in 37−70% yield .…”