Organometallic compounds of the lanthanides. CXXIII. Lanthanide bent-sandwich complexes with the bulky tetramethyl-iso-propylcyclopentadienyl ligand—synthesis, structures and catalytic activity for the hydrosilylation of alkenes/alkynes

Ruthenium Complexes Bearing Bulky Pentasubstituted Cyclopentadienyl Ligands and Evaluation of [Ru(η5‐C5Me4R)(MeCN)3][PF6] Precatalysts in Nucleophilic Allylic Substitution Reactions

“…Synthetic work stimulated by an increasing need for pentamethylcyclopentadiene has also provided two convenient routes to 1‐alkyl‐2,3,4,5‐tetramethylcyclopentadienes on the basis of (i) the reaction between two molecules of 2‐lithio‐2‐butene with an ethyl ester RCO 2 Et and (ii) the addition of an alkyllithium RLi to 2,3,4,5‐tetramethylcyclopent‐2‐en‐1‐one 13,14. Thus, trifluoromethyl‐,15 isopropyl‐16 and tert ‐butyl‐tetramethylcyclopentadienes17 were readily available. We have similarly prepared neopentyltetramethylcyclopentadiene as a yellow oil obtained in a 60 % yield by treating neopentyllithium with 2,3,4,5‐tetramethylcyclopent‐2‐en‐1‐one.…”

“…Synthesis of Cyclopentadienes: The C 5 HMe 4 R 1‐alkyl‐2,3,4,5‐tetramethylcyclopentadienes, R = CF 3 ,15 i Pr,16 t Bu,17 were prepared as reported previously. The C 5 HMe 4 CH 2 t Bu neopentyl cyclopentadiene was prepared as detailed for the tert ‐butyl one17 by using t BuCH 2 Li29 instead of a commercial solution of t BuLi.…”

Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands

“…For other lanthanide(III) complexes with amidinate ligands, see Richter et al (2004), Edelmann (2009Edelmann ( , 2012 and Deacon et al (2014). For related bent sandwich complexes of the lanthanides, see Lueken et al (1987Lueken et al ( , 1989, Schumann et al (1998) and Kü hling et al (2015).…”

Reaction of Alkynes

“…HMPA changes the reaction features: it accelerates the reaction and guides the reaction to provide (E)-alkenes selectively. The addition of an HaM species to alkynes is well known and is effectively promoted by various transition-metal catalysts [9][10][11]. Nickel complexes catalyze the addition of HaSiR 3 (hydrosilylation), HaSnR 3 (hydrostannylation), HaBR 2 (hydroboration), HaAlR 2 (hydroalumination), etc.…”

“…The hydrosilylation of alkynes with alkyl-and arylsilanes, such as Ph 2 SiH 2 , PhMe 2 SiH, and Et 3 SiH [9], has been studied under catalytic systems composed of an Ni(0), triarylphosphine, and butadiyne [12]. In all cases examined, the reaction is characterized by cis-addition of hydrogen and silicon.…”