Zirconium complex compounds, anion

They are based on various metals. Such as zirconium, complexed with cyclopentadienide anions. This type of compound is called a zirconocene and is used with organoalu-minum to make highly regular polymers. The catalyst has the ability to flip back and forth from making atactic to isotactic polypropylene in the same polymerization. The alternating tacticity of the polymer breaks up the crystallinity of the chains and yields an elastomer. Metallocene catalysts are currently very expensive and cannot yet polymerize dienes such as butadiene, so they have only enjoyed limited commercial success in elastomers. However, this is one of the most intense fields of polymer research and many new product breakthroughs are expected in the near future. 

A few strong complexing ions are able to remain coordinated to the cation throughout hydrolysis and condensation. They are therefore included in the structures of the solid. Since these structures include ions other than 0x0 or hydroxo ions, they are called basic salts . In a way, these anions play a role in the formation of the network since, under similar acid conditions, no solid is formed in their absence. Most metallic elements form basic salts in nature, such as carbonates, sulfates and phosphates, which play an important role in mineralogy. A few structurally interesting zirconium(IV) compounds are discussed belosv. 

A particulate gel breaker for acid fracturing for gels crosslinked with titanium or zirconium compounds is composed of complexing materials such as fluoride, phosphate, sulfate anions, and multicarboxylated compounds. The particles are coated with a water-insoluble resin coating, which reduces the rate of release of the breaker materials of the particles so that the viscosity of the gel is reduced at a retarded rate [205]. 

Zwitterionic structures with a borate anion covalently attached to a cyclopentadienyl donor can be obtained by a number of synthetic approaches. In the known compounds, the means by which the borate is tethered to the ring has a significant impact on the properties of the zwitterions. In particular, the length of the tether connecting the ring with the borate is crucial for the stability and intramolecular ion-ion contacts. For example tris cyclopentadienyl zirconium betaine complex in which boron atom is directly bonded to Cp can be generated from boron substituted cyclopentadienyl anion (equation 21). ... 

Compound (CsH4SiMe2NBut)TiCl2 has been synthesized and used as pre-catalyst for ethylene polymerization. The activities and the properties of the polymers have been compared to similar zirconium and hafnium derivatives.720 The consequences of anion-cation interactions on the activity of GGG group 4 metal complexes in olefin polymerizations have been explored for a series of zirconocene derivatives as well as the cationic species [(C5Me4SiMe2NBut)TiMe]+ with the sterically congested tris(perfluorobiphenyl)fluoroaluminate as the counteranion.721 The co-polymerization of ethylene and 1-butene by (CsMe iMe Bu TiC in the presence of... 

Treatment of a benzene solution of the sterically crowded bis(aryloxide)zirconium dibenzyl complex 5 with BIC F5)3 leads to the facile formation of the corresponding zwitterionic species 6 (Scheme 3).44 The molecular structure of 6 features a three-legged piano-stool geometry about Zr with the 7/ -bound benzyl group and the tightly associated benzyl borate anion through r/ -arcne coordination this complex is stable in solution in the presence of propylene and phenylpropyne. In contrast, treatment of the 2,6-di-Buc-substituted aryloxide dibenzyl derivative 7 with B(C6Fs)3 forms the cyclometallated compound 8 after elimination of toluene (Scheme 3) 45 compound 8 was structurally characterized. 

Neutral Ti(CO)6 is an extremely unstable compound which decomposed even below -220 °C, as shown by matrix isolation spectroscopy [165]. The much more stable phosphine derivatives Ti(CO)3(dmpe)2, Ti(CO)5(dmpe), Ti(CO)5(PMe3)2, Ti(CO)4(PMe3)3 have been isolated [166-168]. In contrast, the dianionic salt [Ti(CO)6] (53) is thermally much more stable and decomposes only above 200 C. Complex 53 was obtained by reductive carbonylation of Ti(CO)3(dmpe)2 by alkali metal naphthalenides in the presence of cryptand [169]. Carbonylation of 79 also produces 53 [170]. The naph-thalenide-assisted reductive carbonylation of the zirconium tetrachloride afforded the zirconium analog [Zr(CO)6] (54) [171], which was also derived by carbonylation of the tris(diene) dianion 45 [150]. One anion [R3Sn] effectively stabilizes Ti(CO)e as an air stable monoanionic salt, [R3SnTi(CO)J [172]. 

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