Syntheses of [ethylene-1,2-bis(.eta.5-4,5,6,7-tetrahydro-1-indenyl)]zirconium and -hafnium hydride complexes. Improved syntheses of the corresponding dichlorides

Cationic Organozirconium and Organohafnium Complexes

“…The chiral hydride (107a) catalyzes alkene hydrogenation, though with low stereoselectivity. 31 Hydrogen-deuterium exchange o f (108) and (184) with C 6 D 6 was noted. 71…”

“…46 The p-agostic mono(MeCN) species (86) Hf (107b)). 31 The reaction of [Zr(R)(THF)(r|-C 5 H 4 Me) 2 ] + (R = Me (3) or Bz (7)) with H 2 yields [Zr(H)(THF)(Ti-C 5 H 4 Me) 2 ] + (62), which is a useful reagent for the synthesis of other alkyl complexes (Section 12.2.1.4).…”

Hydrogenation of Unfunctionalized Alkenes

“…The only other catalysts that have reacted with both high conversion and selectivity are the cationic zirconocene complexes (see below) reported by Buchwald [34] .…”

“…A number of other research groups have prepared various chiral nonracemic group (IV) metallocene precatalysts, which generally use an alkyl lithium, such as n -BuLi, as a cocatalyst for activation [67] . Although the best It was not until Buchwald and coworkers reported the use of reduced forms of Brintzinger ' s complexes (45) (X 2 = binaphtholate) [68] and (46) (X = Me) [34] that group (IV) metallocenes (Figure 2.12 ) became interesting synthetically. The titanocene precatalyst (45) (X 2 = binaphtholate), activated with n -BuLi and stabilized with phenylsilane, was used in the asymmetric hydrogenation of trisubstituted alkenes with great success; many substrates were reduced in > 90% ee (entries 1 -8, Table 2.9 ) [68] .…”

Activation of Metallacyclopropenes, five‐membered Metallacyclocumulenes and Metallacyclopentynes of Zirconium with iBu2AlH

“…These results were compared with results in which the complexes Cp 2 Zr(h 4 -1,2,3,4-H 2 C 4 H 2 ) (8), rac-(EBTHI)ZrF 2 (9), [13] rac-(EBTHI)ZrCl 2 (10), [14] [rac-(EBTHI)-Zr(H)(m-H)] 2 (11) [15] and rac-(EBTHI)-Zr(F)CH 2 -CH 2 (2-Py) (12) [16] were activated by the addition of i-Bu 2 AlH together with water, too. Additionally, the complexes rac-(EBTHI)ZrF 2 (9), rac-(EBTHI) ZrCl 2 (10) and rac-(EBTHI)ZrMe 2 (13) [17] were activated by MAO to understand the importance of alkylation for the formation of these active catalysts.…”