Imino-zirconium complex

Chmura et al. also prepared air and moisture resistant chiral imino phenoxide complexes of zirconium and titanium, 14 [16]. They envisioned to study the effect of supporting ligand chirality on the stereoselectivity of LA ROP reaction. But at the end, they did not gain acceptable evidence enable to support any relationship. They showed that all isolated polymers had similar and moderate heterotactic microstructure which implied simple chain end control mechanism and resulted to the selective racemic enchainment during the propagation process. First, they investigate polymerization in toluene at 80°C and ambient temperature in which titanium complexes were absolutely inactive and zirconium coxmterparts showed moderate activity after 2 and 24 hours, respectively. Then they checked out solvent free conditions at 130°C and received almost complete conversion after 30 minutes for both titanium and zirconium alkoxide complexes (Table 7.2, entry 33-36). In this condition, titanium coxmterpart, in contrast to zirconium, resulted to full atactic polymer. Their investigation also showed that zirconium complex retained its activity in moisture or with lactic acid impurity in crude monomer which is deleterious for most metal alkoxide catalysts. 

Iminophosphoranes, mercuration, 2, 432 (Iminophosphoranyl)ferrocenes, synthesis, 6, 202 Imino-pyrrolate systems, with zirconium, 4, 1138-1139 Imino-pyrrolides, with Zr(IV) and Hf(IV), 4, 780 Imino-pyrrolyl ligands, in chromium complexes, 5, 355 Iminosilanes, reactions, 3, 440 Imprinted complexes, on oxide surface, 12, 810 Impurities, glovebox techniques, 1, 215 Inclusion chemistry... 

The first catalytic asymmetric allylation of imines has been reported using allyltri- -butyltin in the presence of a chiral 7r-allylpalladium complex.179 Zirconium is also demonstrated as a metal center for the design of chiral Lewis acid catalysts that are suitable for the activation of bidentate imino compounds.180 Jprgensen reports high enantio-selective allylation of ct-imino esters (Equation (52)).181... 

Several new complexes of iminophosphoranes have been reported by Cavell and co-workers (Scheme 9). Reaction of dimethyl zinc with bis- trimethylsilyl-imino-diphenylphosphorano methane (61) yields zinc complex (62) via elimination of methane. Complex (62) did not react with adamantyl nitrile or isonitrile but does undergo nucleophilic addition reactions with hetereroallenes such as carbodiimides and isocyanates. Thus, treatment of (62) with adamantyl isocyanate produces the novel tripodal alkyl zinc complex (63). Iminophos-phorane (61) reacts with [Sm(NCy2)3(THF)] and tetrakis(benzyl)zirconium(IV)... 

Using the zirconium carbene complexes 54 as olefination agents, stereochemical control can be achieved by replacing a carbonyl group of the substrates with an imino group (=NR) (Scheme 4.50) [119). The olefination of benzaldehyde with... 

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