Hafnium complexes allyl

Bercaw and co-workers showed that pentamethylcyclopentadienyl-aminoborole complexes of hafnium and zirconium 52 react with allyl magnesium bromide in diethyl ether to yield the allyl complexes 53 (Equation 8) <1997JOM65>. 

This reaction has been extended to the reaction between aldehydes and alkenyl complexes of boranes, silanes, and stannes to give allylic alcohols, " where the reaction with alkenyl complexes of silanes is known as the silyl-Prins reaction. In addition, several Lewis acids-mediated or -promoted Prins reactions have recently been developed, including the application of TMSI, hafnium (IV) bis(perfluorooctanesulfonyl)amides (in fluorous biphase system),iron (III) species," and 2,6-di-f rf-butylphenoxy(difluoro)borane. J... 

At higher temperatures, allyl complexes are no longer rigid they become dynamic, fluxional compounds. Therefore, AM2X2 spectra become AX4 spectra. Temperatures of such transitions for various compounds range from 200 to 450 K. The hafnium allyl compound [Hf( / -C3H5)4] exhibits an AX4-type spectrum even at 199 K. For dynamic... 

Titanium group allyl compounds are sensitive to air, water, and alcohols. Tetrallyl derivatives of zirconium and hafnium are dynamic compounds. The complex Hf(allyl)4 gives the AX4 type NMR spectrum even at very low temperatures (199 K). The Ti(III) complexes are paramagnetic magnetic moments correspond to one unpaired electron and, for various allyl groups, vary in the 1.47-1.75 BM range. The properties of allyl... 

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