Heterobimetallic metallocenes

Recently, the quadratic hyperpolarizabilities of heterobimetallic metallocenes have also been studied using the HRS technique [116-118]. The addition of ametal-pentacarbonyl function to a pyridyl acceptor group appeared to substantially increase the NLO efficiencies of the ferrocene-pyridyl compound [117, 118]. Notwith-... 

Both compounds exhibited three oxidation states. Cyclic voltammetry, in the presence of host / -cyclodextrin revealed that the Fc" "-Co form is not bound to this ligand, the Fc-Co oxidation state forming a stable complex by inclusion of the ferrocene site, while the fully reduced form Fc-Co presenting two binding sites for the CD host A large series of heterobimetallic metallocenes in which a zirconocene moiety was associated with another metallocene (M = Rh, Mn, Ru, Fe, Co, Zr, Hf) in the same molecule were synthesized in order to check their ability to polymerize ethylene. The Zr-Co member 365 of this series was shown to be among the most active catalysts, and it also provided the most uniform polymers (Figure 69). ... 

SCHEME 10 Preparation of half-metallocene Group-4 heterobimetallic catalysts. 

TABLE 1 Data Characterizing Ethylene Polymerization in the Presence of Metallocene-Derived Heterobimetallic Catalysts.°... 

From this result it is clear that the highest activity is observed for the heterobimetallic complexes in which a metallocene based active metal... 

Treatment of Cp2ZrCl2 with LiAlH4 and then HsGaNMes or reaction of the preformed hydride Cp2ZrH2 with H3 AINMes affords the heterobimetallic complex (15). Boron-containing heterobimetallic complexes (16) can be prepared by reaction of metallocene dichlorides with the cyclic hydroborate anion [H2BC5H10] then reduction of MX l bond with LiH. 

The reaction of bis(phenylacetylide) zirconocenes (C5H4R)2Zr(C=CPh)2 (R = H, Me, Buc, SiMe3) with vanado-cene in toluene at ambient temperature gives heterobimetallic complexes 708531 532 (Equation (44)). The molecular structures show the Cp2V and CpR2Zr metallocene moieties bonded to a butadiene framework through the two... 

Broad or bimodal molecular mass distributions have been obtained using mixtures of metallocenes,452 487-491 linked homo- and heterobimetallic bis(cyclopentadienyl) complexes for broad molecular mass distribution,492 or amino-functionalized bis-Cp complexes.476... 

Scheme 32.4 Synthesis of heterobimetallic complexes derived from M (OR>2 aUcoxides and group 4 metallocenes.

Heterobimetallic complexes involving group 4 metallocene and Ni(0)-cycloolefin moieties have been prepared from Ni-alkyne complexes. For instance, reacting the butadiyne-Ni(O) complex Ni(r7 -Ph-G=G-G=G-Ph)(PPh3)2, 10, with MGp2 precursors (M = Ti and Zr) leads to the species 11, in which metallacyclopentadienes are coordinated in ry -fashion to the Ni center (Equation (2)). It is important to note that these complexes are stable with Ph substituents only. 

Scheme 28 Synthesis of Al-O-M Al/group 4 metallocenes heterobimetallic complexes for use in ethylene polymerization...

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