Zirconium complexes reactions with isocyanates

The reactivity of zirconium imido complexes supported by a dibenzotetraaza[14]annulene (taa) macrocycle ligand toward a range of unsaturated substrates has been examined. Reaction with t-butyl isocyanate cleanly generated the cycloaddition product Zr N(2,6-( -Pr)2C6H3)C(0)N(t-Bu) (Me4taa) (equation 21). ... 

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)... 

Zirconium isoprene and butadiene complexes 314 undergo reaction with methyl-, t-butyl-and phenyl isocyanate to give 1 1 adducts 315 and 1 2 adducts 316. ... 

Zirconium and hafnium tetraalkoxides are highly reactive compounds. They react with water, alcohols, silanols, hydrogen halides, acetyl halides, certain Lewis bases, aryl isocyanates and other metal alkoxides. With chelating hydroxylic compounds HL, such as j8-diketones, carboxylic acids and Schiff bases, they give complexes of the type ML (OR)4 these reactions are discussed in the sections dealing with the chelating ligand. 

Yasuda H, Okamoto T, Matsuoka Y, Nakamura A, Kai Y, Kanehisa N, Kasai N (1989) Diverse reaction courses in the controlled carbometalation of heterocumulenes with zirconium-diene complexes and molecular structures of carbon dioxide, isocyanate and ketene 1 1 and 1 2 inserted compounds. Organometallics 8 1139-1152... 

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