Yttrium alkyl complex

Table 10 shows the results of polymerization of oc-olefins catalyzed with trivalent complexes. When a bulkiler tBuMe2Si group instead of the Me3Si group was introduced into the yttrium complex, the racemic complex was formed exclusively [74c]. However, this alkyl complex did not react with olefins, and hence it was converted to a hydride complex by reaction with H2. The complex obtained was reactive to various olefins and produced polymers at... 

Neutral lanthanide complexes are convenient models for the cationic zirconocene systems and avoid complications due to the presence of counteranions and the limited solubility of ionic compounds. Dynamic NMR studies on yttrium complexes 44-46 has allowed the determination of the alkene binding enthalpy, the activation enthalpy of alkene dissociation, and the relative rates of dissociation and alkyl site exchange (site epimerisation) (Scheme 8.20). Compared to the Zr... 

Yttrium bis(alkyl) and bis(amido) complexes of the type [LY(CH2SiMe3)2] bearing N,0-multidentate ligands (L), such as p-diimines, displayed high activity for the ROP of L-lactide at room temperature (100% conversion in most experiments in THF within 2-60 min). In this case, an influence of the ligand framework and the geometry of the alkyl(amido) species (single site or double site) on the catalytic activity have been reported [106]. 

Finally, a samarium aluminate tetramer featuring /J-dikeliminalo ligands was obtained in low yield (20%) by J. Arnold et al. (Scheme 54) [224], Once again this example corroborates the feasibility of selective [amide] [alkyl] transformations in N-ligand-based postlanthanidocene chemistry, previously observed for octaethylporphyrin yttrium complexes by C.J. Schaverien [225, 226],... 

The yttrium complex reacts with Lewis bases, like amines, tetrahydrofurane or phosphine oxides, but less readily with soft donors like phosphines, as monitored by NMR spectra. The triplet at —0.81 ppm collapses to a doublet at lower field, but no isolation of an adduct was possible, pointing out a weaker Lewis acidity for Y" in comparison to Sc. Alkyl- or alkylchloroaluminum compounds react with dimeric dicyclopentadienyl methyl yttrium to give di-ju-alkyl- or di-ju-chloro-bridged compounds as shown in eqs. (41) and (42). The chloro- and methyl-bridged complex (eq. 43) decomposes with formation of trimethyl aluminum and dicyclopentadienyl... 

Homoleptic lithium complexes [Li NNE 2]Cl (E = 0, S), containing Juc-coordinating NNE-donor hgands prepared from bis(3,5-dimethylpyrazol-l-yl)methanewith BuLi and alkyl- or aryl-containing isocyanates or isothiocyanates, have been used to synthesize a series of scandium and yttrium complexes. ... 

Otero A, Lara-Sanchez A, Femandez-Baeza J, et al. New achiral and chiral NNE heteroscorpionate ligands. Synthesis of homoleptic lithium complexes as well as halide and alkyl scandium and yttrium complexes. Dalton Trans. 2010 39 930-940. 

Scheme 15 Reactivities of bis(iminophosphoranyl)methanediide yttrium complexes toward benzophenone alkyl vs. carbene based reactivity...

The acetylacetonates are stable in air and readily soluble in organic solvents. From this standpoint, they have the advantage over the alkyls and other alkoxides, which, with the exception of the iron alkoxides, are not as easily soluble. They can be readily synthesized in the laboratory. Many are used extensively as catalysts and are readily available. They are also used in CVD in the deposition of metals such as iridium, scandium and rhenium and of compounds, such as the yttrium-barium-copper oxide complexes, used as superconductors. 1 1 PI Commercially available acetyl-acetonates are shown in Table 4.2. 

The guanidinate-supported titanium imido complex [Me2NC(NPr02l2Ti = NAr (Ar = 2,6-Me2C6H3) (cf. Section IILB.2) was reported to be an effective catalyst for the hydroamination of alkynes. The catalytic activity of bulky amidinato bis(alkyl) complexes of scandium and yttrium (cf. Section III.B.l) in the intramolecular hydroamination/cyclization of 2,2-dimethyl-4-pentenylamine has been investigated and compared to the activity of the corresponding cationic mono(alkyl) derivatives. 

Marks et al. reported the co-polymerization of ethylene and 1-hexene by using ansa-type complexes of lanthanide metals [127]. Recently, bulky alkyl substituted ansa-type metallocene complexes of yttrium have been reported to exhibit high activity for the polymerization of 1-hexane. [114, 119, 128]... 

Limited research studies [6] show that the minerals from the yttrium groups can be recovered using alkyl hydroxamate collectors which form complex reactions with REO. 

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