1,2,3,4-Tetramethyl-5-(trifluoromethyl)cyclopentadienide: a unique ligand with the steric properties of pentamethylcyclopentadienide and the electronic properties of cyclopentadienide

Complete Defluorination of 1,2,3,4-Tetramethyl-5-(trifluoromethyl)cyclopentadiene by Titanium Tetrakis(dimethylamide)—Selective Formation of a Cyclic Hexanuclear Titanium Fluoroamide and 6,6-Dimethylaminotetramethylfulvene

“…[2,3] In order to understand steric and electronic effects of Cp and Cp* ligands, especially as a driving force in metallocene chemistry, Gassman et al developed the 1,2,3,4-tetramethyl-5-(trifluoromethyl)cyclopentadiene ligand (Cp* CF3 , 1). [4] The Cp* CF3 ligand shows the electronic properties of a Cp and the steric bulk of Cp* (Scheme 1). Scheme 1.…”

“…Transition metal compounds of Cp* CF3 are accessible from the neutral 2,3,4,5-tetra-methyl-1-trifluoromethylcyclopentadiene (Cp* CF3 -H, 1). [4] Additionally, tetramethyltrifluoromethylcyclopentadienide can be readily generated in gas phase, and it was proposed by Kass et. al.…”

An Efficient Entry to Planar Chiral Organometallic Complexes via Pd-Catalyzed Asymmetric Hydrogenolysis

“…Reaction of complex 5c was then examined to clarify whether steric or electronic parameters are responsible for this low asymmetric induction. The 1,2,3,4-tetramethyl-5-(trifluoromethyl)cyclopentadiene ligand (Cp* CF3 ) developed by Gassman [12] exhibits the electronic properties of a Cp and the steric bulk of a Cp*, which makes 5c isoelectronic to 5a and isosteric to 5b. The reaction furnished (S)-7c with an intermediate enantiomeric excess of 78% ee, suggesting that both electronic and steric properties influence the enantioselection of the reaction.…”

Crystal structure of twinned (η5-C5(CH3)4CF3) (η5-C5(CH3)5)Ru

“…In a recent study [1] Gassman et al were able to provide a rational synthesis for the 1,2,3,4-tetramethyl-5-trifiuoromethylcyclopentadienyl ligand. It was designed as an electronic equivalent of unsubstituted cyclopentadienyl (Cp) and should have the steric properties of pentamethylcyclopentadienyl (Cp*).…”

“…Attempts to deprotonate the cyclopentadiene 1 failed as described by Gassman [1]. The synthesis of the mixed mthenocene had to be carried out on a different mute: The mild method described by Koelle et al using the versatile pentamethylcyclopentadienylmethoxoruthenium dimer [3] was applied.…”