Non-bridged amido cyclopentadienyl complexes of titanium: synthesis, characterization, and olefin polymerization catalysis

Radical and migratory insertion reaction mechanisms in Schiff base zirconium alkyls

“…A similar reaction was carried out using [ZrL 4 (CH 2 Ph) 2 ]. In both cases, the 1 H NMR spectra indicated formation of [B(C 6 F 5 ) 3 (CH 2 Ph)] À [15]. Below ca.…”

“…1 H NMR spectra were recorded at À80°C and at +10°C increments up to room temperature. Resonances for [B(CH 2 Ph)(C 6 F 5 ) 3 ] À were observed at low temperature [15], indicating that a reaction had taken place, but while some resonances assignable to a cationic species [Zr(L 10 ) 2 (CH 2 Ph)] + were observed, by À40°C extensive decomposition had occurred. This result and the attempts to form [ZrL 1,4 (CH 2 Ph)] + (Section 2.8), do not bode well for isolation of a stable alkyl cationic species such as that implicated in olefin polymerisation catalyses by these complexes.…”

Synthesis, structure and ethylene polymerization behavior of titanium phosphinoamide complexes

“…The Ti-N bond lengths of the complex 2a (2.004(2) and 2.000(2) Å ) are longer than that of constrained geometry catalyst (CGC) complexes such as [(C 5 Me 5 )SiMe 2 (N t Bu)]TiCl 2 (1.907(4) Å ) [26], and non-bridged Ti(g 5 -C 5 Me 5 )[N(Me)Cy] (1.870(3) Å ) [7] [27], and ( t Bu 3 P@N)TiCl 3 (1.709(6) Å ) [28], but closer to the estimated value (2.02Å ) for Ti-N single bond according to PaulingÕs covalent radii [29]. The bond lengths Ti-P are 2.4928(9) and 2.4912(9) Å , which are somewhat shorter than those Ti-P bond distances shown in the literature (ca.…”

“…Within this area, mono(cyclopentadienyl) complexes of group 4 with an additional monoanionic p-donor ancillary ligand are currently receiving increasing attention. In comparison to conventional metallocene initiators Cp 2 MX 2 , monocyclopentadienyl complexes CpM(L)X 2 offer the advantage of catalyst modification by changing the nature of the spectator ligand, L. Typical p-donor ancillary ligands L that have been used in these catalysts are substituted phenoxides [5,6], amido [7][8][9], amidinate [10][11][12], ketimides [13][14][15], phosphinimides [16], and iminoimidazolidide [17].…”

Efficient living polymerization of 1-hexene by Cp*TiMe2(O-2,6-iPr2C6H3)-borate catalyst systems at low temperature

“…Nonbridged half-metallocene type group 4 transition metal complexes of the type, Cp M(L)X 2 (Cp = cyclopentadienyl group; M = Ti, Zr, Hf; L = anionic ligand such as OAr, NR 2 , NPR 3 , etc. ; X = halogen, alkyl) [1][2][3][4][5][6][7][8][9][10][11][12] have been one of the promising candidates as the new type of olefin polymerization catalysts, because some of these complexes exhibited unique characteristics that are different from both ordinary metallocene type [13] and so-called 'constrained geometry' (linked half-metallocene) type catalysts [13b, [14][15][16][17][18][19].…”