677796-56-4Relevant articles and documents
Synthesis, Structure, and Reactivity of Hydroxylaminato Alkyltitanium Complexes
Mahanthappa, Mahesh K.,Cole, Adam P.,Waymouth, Robert M.
, p. 1405 - 1410 (2008/10/09)
Alkyltitanium complexes bearing hydroxylaminato ligands were synthesized by two methods: (i) reaction of the stable nitroxide radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) with TiCl3 to generate (TEMPO)TiCl3 (1) followed by alkylation with PhCH2MgCl to furnish (TEMPO)Ti(CH2Ph)3 (2), and (ii) protonolysis of Ti(CH2Ph)4 (3) with hydroxylamines to yield (R 2NO)2Ti(CH2Ph)2 (R = CH 2Ph (4), Et (5)). 1H NMR studies of these compounds demonstrate that the hydroxylaminato ligands exhibit both η1- and η2-binding modes with varying degrees of hemilability. X-ray crystallographic analysis of 5 shows that titanium adopts a six-coordinate propeller conformation in which the hydroxylamine anions are η2-bound. The reaction of the complex 2 with B(C 6F5)3 at 20°C forms 1 equiv of toluene and a cationic benzyltitanium complex exhibiting strong η6-PhCH 2B(C6F5)3 anion coordination, in which one of the TEMPO methyl groups has undergone C-H bond activation as evidenced by 1H, 13C NMR, gHSQC, gHMBC, and gROESY experiments. Complexes 2-5 exhibit very low activities for propylene polymerization.
