Carrier influence on the paramagnetic and catalytic properties of supported titanium complexes

Study on the NaNp/CpTiCl3/Al2O3–SiO2 system

“…A similar deactivating effect of the carrier has already been described for the BuLi (Et 3 Al) CpTiCl 3 /Al 2 O 3 -SiO 2 (Bu = butyl, Et = ethyl) system, where for the same range of Al 2 O 3 content in the carrier trace yield of the reduction of titanium [IV] ions was noted [26].…”

“…This is due to the "spin-spin exchanged interaction" effect in paramagnetic complexes as a result of too close a distance between them [19,26].…”

“…The EPR spectra of cyclopentadienyl Ti[III] complexes supported on inorganic carriers typically are broad signals characteristic of the tetrahedral surroundings of the titanium ion of a distorted axial or rhombic symmetry [26].…”

Study on the NaNp/Al2O3–SiO2 system

“…The aluminosilicate phase in the gels containing from 30 to 50 wt% of Al 2 O 3 prohibits the reduction of supported cyclopentadienyl titanium (IV) complexes with butyllithium or with triethylaluminum [15,16] and direct butadiene polymerization to 1,4-cis-polybutadiene [17] in the presence of π -allylnickel complexes supported on alumina-silica gels. These complexes, supported on the γ -Al 2 O 3 phase, catalyze the polymerization to 1,4-transpolybutadiene [17,18].…”

“…Thus, when applying alumina-silica gels with a gradual increase of Al 2 O 3 content, it is possible to prove that the determined phase or active surface centers, e.g., Lewis or Brønsted acid sites, catalyze an investigated reaction or, e.g., Lewis base sites activate supported titanium complexes in olefin hydrogenation [16].…”