Binary copolymerizations of styrene, isoprene, butadiene and 4-methyl-l,3-pentadiene, in the presence of the catalyst cyclopentadienyltitanium trichloride-methylaluminoxane (CpTiCI,-MAO), are investigated. The reactivity ratios as well as the reactivities of the different monomers in homopolymerization are tentatively correlated to a possible polymerization mechanism. A qualitative explanation of the reactivity of different monomers in homo-and copolymerization is achieved by considering the nucleophilicity of the monomers and the electrophilicity of the active species. The latter is affected by the nature of the bond between the active Ti and the last unit of the growing chain end. The block copolymerization of ethylene with styrene is also tentatively explained by considering that the more the active species are electrophilic the less they should be selective toward monomers of different nucleophilicity.

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The solution structure of AlMe F and its reactivity with a prototypical ansa-metallocene have been investigated by advanced NMR techniques, in an attempt to indirectly shed some light on the structure and working principles of methylalumoxane (MAO) mixtures in olefin polymerization. In solution, AlMe F gives rise to a complex equilibrium of oligomeric species, including a heterocubane [(Me Al) F ] tetramer, resembling the behavior of MAO. This complex mixture reacts with (ETH)ZrMe (ETH=rac-[ethylenebis(4,5,6,7-tetrahydro-1-indenyl)]) to afford [(ETH)ZrMe (μ-F)(AlMe F) AlMe ] inner-sphere ion pairs through successive insertions/deinsertions of AlMe F units into the Zr⋅⋅⋅(μ-F) bond.

This article describes three cases of Datura stramonium intake on two nonconsecutive days. In the first case, the patient took a small amount of D. stramonium seeds without showing any symptoms of intoxication. The other two patients had taken a considerable amount of seeds and reported a sudden surge in strength and energy, with some aggressive compulsion towards their peers. They showed delirium as well as confusion and disorientation. The absence of any specific legislation makes D. stramonium a tempting alternative to other psychoactive substances. Thus, it is extremely important to be able to recognize its symptoms so as to be able to diagnose any signs of intoxication properly.