Zirconium aryloxides

Evans JW, Ansari AM, Ziller WJ. Synthesis of zirconium aryloxide complexes eontain-ing pendent vinyl groups. Inorg Chem 1999 38(6) 1160-4. 

Zirconium dichiorohis(dimethylamide) [87227-57-4] ZrCl2[N(CH2)2]2 h made direcdy from methylamine and zirconium tetrachloride but all of the halogens can be substituted by treating zirconium tetrachloride with the appropriate lithium alkylamide (229). Zirconium arylamines are made from zirconium alkoxides which first are converted to aryloxides (230). 

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. 

In the case of zirconium and hafnium the lack of accessible dichlorides means that alkyl derivatives are generated via the corresponding homoleptic alkyl intermediates. With bulky 2,6-di-ferf-butylphenoxide the tris-benzyls [(ArO)ZrR3] can be isolated and studied. " The dialkyls [(ArO)2MR2] (M = Zr, Hf R = Me, benzyl) can also be isolated for bulky aryloxides. In the case of 2,6-diphenylphenols the monomethyl species [(ArO)3ZrMe] are readily formed by simple addition of parent phenol to the dimethyl compound. 

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