Zirconium complexes amines

Zirconium tribenzyl complex 212 incorporating diisopropyltriazacyclonone, a type of mono-anionic, tridentate diamino-amido [/V,iV ,./V] ligand, was obtained via alkane elimination (Scheme 42) alternatively, this complex can also be prepared via either salt metathesis or amine elimination approaches.179 The crystal structure of 212 reveals a monomeric form on heating at 80 °C in benzene solution for 24 h, this complex undergoes elimination of 1 equiv. of toluene, affording complex 213 bearing a dianionic, acyclic, diamido-amino [/V-,iV,./V-] moiety. 

Amine or hydrocarbyl elimination was also employed to prepare the following t -mono-Cp-silylamido derivatives (Scheme 106), including zirconium bis(diethylamido) complexes 469 with variations on the ring and amido substitutions,330 zirconium dibenzyl complex 4 70,331 t -mono-Ind-silylamido zirconium complex 471, 0 isodicy-clopentadienyl zirconium complexes 472,332 and enantiomerically pure zirconium bis(dimethylamido) and dichloro complexes 473333 with the R or S -CH(Me)Ph group attached to the amido nitrogen the last two complexes of this... 

Highly enantioselective catalytic desymmetrization of meso-epoxides through nucleophihc ring opening was first effectively demonstrated by Nugent, who found that a zirconium trialkanolamine complex catalyzed the addition of azi-dosilanes to meso-epoxides (Scheme 1) [3]. Azide has been the most widely explored nitrogen nucleophile [4,5,6,7], in part due to its utiHty as an amine sur-... 

Efficient reactivity with secondary amines points clearly toward alternative mechanistic profiles from the weU-estabhshed [2-E2] cycloaddition of a metal imido to a C-C multiple bond. Indeed, early computational work on a cyclopentadienyl system suggested that while the [2-E2] cycloaddition step is energetically feasible, the subsequent protonolysis step for catalyst turnover is turnover-limiting [40, 59]. More recently, Scott and coworkers [60] showed experimentally that proton transfer in the release of product and generation of the requisite zirconium imido complex can be turnover-limiting (Scheme 15.10). 

The activity of 36 200 kg mol h (Table 15.1) is comparable to the extremely high activities reported for zirconium amine-bis(phenoxide) complexes [20]. Upon reducing the polymerization temperature to -30 "C, the activity dropped to 2030 kg mol h" however, at this temperature the poly(l-hexene) produced... 

The extraction of metals by liquid amines has been widely investigated and depends on the formation of anionic complexes of the metals in aqueous solution. Such applications are illustrated by the use of Amberlite LA.l for extraction of zirconium and hafnium from hydrochloric acid solutions, and the use of liquid amines for extraction of uranium from sulphuric acid solutions.42,43... 

Complexes of tetravalent zirconium with organic acids, such as citric, tartaric, malic, and lactic acids, and a complex of aluminum and citric acid have been claimed to be active as dispersants. The dispersant is especially useful in dispersing bentonite suspensions [288]. Polymers with amine sulfide terminal moieties are synthesized by using aminethiols as chain transfer agents in aqueous addition polymerizations. The polymers are useful as mineral dispersants [1182]. 

Other examples of this synthetic strategy are known for example, a recent zirconium polymer by Illingsworth and Burke (8), who joined amine side groups of a zirconium bis(quadridentate Schiff-base) with an acid dianhydride to give amide linkages. Once again, caution is necesary, as Jones and Power (2) learned when they attempted to link metal bisO-diketonates) with sulfur halides that is, they obtained insoluble metal sulfides because the p-diketone complexes which they used were fairly labile and the insolubility drove the reactions to completion in the wrong direction. 

Aryl chlorothioformates, 23 628 Aryl complexes, zirconium, 26 655 Aryl ethers, uses for, 70 581 2-Arylglycine esters, 72 166 Aryl halide amination, 9 278 Aryl halides, reaction with carbon monoxide, 5 11 Arylhydrazines, 9 270 Arylmethane dyes, 9 503... 

Aminoborollide complexes of zirconium and hafnium that incorporate both Lewis acid and Lewis base sites have been explored.1 a In molecules such as 9, the amine nitrogen carries an electron lone pair while the d° metal center is acidic ... 

Representative metal complexes employed for the catalytic asymmetric Strecker reaction are summarized in Figure 4.2. Aluminum-, titanium-, lanthanoid-, and zirconium-based catalysts are highly efficient. Direct one-pot synthesis starting from aldehydes, and amines is reported using the Zr complex described in Figure 4.2. ... 

Zirconium(IV) and hafnium(IV) halides form adducts with a variety of monodentate and polydentate amines. Typical complexes are listed in Table 3. In general, these compounds are air- and moisture-sensitive white solids (yellow when the halide is iodide), thermally stable and insoluble in most organic solvents. 

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