No abstract

The solubility of NbCl 5 , TaCl 5 , TiCl 4 , ZrCl 4 , and HfCl 4 in neutral [BMIM][AlCl 4 ] (BMIM = 1-butyl-3-methylimidazolium) was determined. While TiCl 4 was immiscible with the neutral ionic liquid, 0.80 molar equivalents of ZrCl 4 and stoichiometric amounts of HfCl 4 dissolved in the melt at ambient temperature. The crystal structures and the unit cell parameters of [BMIM]

Based on two well-established ligand systems, the aminopyridinato (Ap) and the phenoxyimine (FI) ligand systems, new Ap-FI hybrid ligands were developed. Four different Ap-FI hybrid ligands were synthesized through a simple condensation reaction and fully characterized. The reaction of hafnium tetrabenzyl with all four Ap-FI hybrid ligands exclusively led to mono(Ap-FI) complexes of the type [(Ap-FI)HfBn2 ]. The ligands acted as tetradentate dianionic chelates. Upon activation with tris(pentafluorophenyl)borane, the hafnium-dibenzyl complexes led to highly active catalysts for the polymerization of 1-hexene. Ultrahigh molecular weights and extremely narrow polydispersities support the living nature of this polymerization process. A possible deactivation product of the hafnium catalysts was characterized by single-crystal X-ray analysis and is discussed. The coordination modes of these new ligands were studied with the help of model titanium complexes. The reaction of titanium(IV) isopropoxide with ligand 1 led to a mono(Ap-FI) complex, which showed the desired fac-mer coordination mode. Titanium (IV) isopropoxide reacted with ligand 4 to give a complex of the type [(ApH-FI)2 Ti(OiPr)2 ], which featured the ligand in its monoanionic form. The two titanium complexes were characterized by X-ray crystal-structure analysis.

Long chain running: The polymerization performance of guanidinato titanium(IV) olefin catalysts is tuned by monodentate ancillary ligands. Polymerization activities of up to 8800 kgPE molcat.−1 h−1 bar−1 together with molecular weights of 2500 kg mol−1 were observed (see figure; d‐MAO=dry methylalumoxane). Ligand transfer of the additional donor ligands has to be avoided.