Synthesis, Characterization And Catalysis Behavior Of Complexes Based On Acenaphthene And Phenanthrene Imine Derivative Ligands

Polybutadiene (PB) and polyisoprene (PIP) have been the most widely used synthetic rubbers. BIAN and BIP have the unique properties of combining both the diimine and naphthalene (or phenanthrene ) p systems and can act as strongerσ-donors towards the metal. In addition to be used as neutral ligands, Ar-BIAN and Ar-BIP ligands might form stable mono- and di-, and possibly even tri- and tetraanions by electron transfer to their mixed 14(or 16)-electron imine-naphthalene (or phenanthrene ) p system,we have successfully designed and synthesized series of Cr , Fe and Co complexes by one pot reaction of CrCl₂(THF)₂ ,FeCl₂ and CoCl₂ with Ar-BIAN and Ar-BIP ligands. The catalytic behaviors of these complexes for diene polymerization were also investigated. Upon activation with MAO, these complexes show moderate to high activities in butadiene and isoprene polymerization affording cis-1,4 enriched polymers.In chapter 2, taking into account the unequal electronic effect and stereo effect of ligands, we obtained 8 chromium catalysts according to change the constituent on the imine. These complexes have been analyzed by IR, elemental analysis and single crystal X-ray diffraction analysis. X-ray crystallographic analysis reveals that the geometries around the chromium atom can be best described as octahedral . The ability of diene polymerization under different catalysis systems have been examined, the influence of different substituents, the ratio of Al/Cr and the polymerization time has been studied. While when activated with MAO, these complexes show medium to high activities towards isoprene polymerization with varied cis-1,4 selectivity at room temperature and the diimine complexes show relatively higher activities than that with monoimine derivates. When 3d was used as precatalyst, the conversion increased with the increasing Al/Cr ratios and 82.6% conversion was achieved at Al/Cr = 500. Upon activation with MAO, these complexes also show high activities in butadiene polymerization at room temperature. It is worth to note that the selectivity are influenced by the polymerization emperature and the cis-1,4 selectivity gradually increased from 89.3% at 25°C to 95.2% at– 40°C.In chapter 3, a number of chromium complexes supported by ligands N-aryl- 9,10-iminophenanthraquinone Ar-IPQCrCl₂(THF)₂ (1, Ar = 2,6-Me₂C₆H₃; 2, Ar = 2,6-Et2C₆H₃; 3, Ar = 2,6-iPr₂C₆H₃) were synthesized from the reaction of mono- imine ligands with CrCl₂(THF)₂ in CH2Cl₂. Molecular structures of 1 and 3 were revealed to be monomeric with the chromium atoms in distorted 10 octahedral geometries. Similar reactions of CrCl₂(THF)₂ with N,N-bis(arylimino)phenanthrene ligands afford the diimine complexes Ar1,Ar2 BIPCrCl(μ-Cl)3Cr(THF) Ar1,Ar2 BIP (4, Ar1 = Ar2 = 2,6-Me₂C₆H₃; 5, Ar1 = Ar2 = 2,6-Et2C₆H₃; 6, Ar1 = Ar2 = 2,6-iPr₂C₆H₃; 7, Ar1 = 2,6-Me₂C₆H₃, Ar2 = 2,6-iPr₂C₆H₃). The X-ray diffraction analysis show that 4, 5 and 7 are chlorine-bridged dimers with each chromium atom in a distorted octahedral geometry. Upon activation with MAO, all these complexes exhibit good catalytic activities for isoprene polymerization affording thepolyisoprene with dominant cis-1,4 unit.In chapter 4, two series of iron and cobalt based catalysts supported by ligands N-aryl-9,10-iminophenanthraquinone were synthesized from the reaction of mono-imine ligands with FeCl₂ and CoCl₂ powder in THF, activated by MAO, have been investigated in 1,3-butadiene polymerization. These complexes have been analyzed by IR, elemental analysis and single crystal X-ray diffraction analysis. When activated with MAO, these complexes show medium to high activities towards butadiene polymerization with varied dominant cis-1,4 selectivity at room temperature.