Synthesis And Characterization Of Amidate Divalent Lanthanide Amides And Their Applications In The Chemical Fixation Of Carbon Dioxide

Based on three new amidate ligands HL(HL1 = tBu C6H4CONHC6H3(iPr)2; HL2 = Cl C6H4CONHC6H3(iPr)2; HL4 = Me3C6H2CONHC6H3Me2), three amidate divalent lanthanide complexes were synthesized. All complexes were well characterized including X-ray diffraction determination. The catalytic activities of these complexes both on the cyclization reaction of 2-aminobenzonitriles with CO2 and the reaction of aziridines with CO2 were investigated, meanwhile the effects of different ligands and metals of the complexes were studied. The main results are as follows:1. Reactions of HL1, HL2 with Eu[N(Si Me3)2]2 in 1:1 molar ratio afforded amidate lanthanide amidates {L1Eu[N(Si Me3)2](THF)}2(1) and { L2Eu[N(TMS)2]THF}{L22Eu(THF)2}(2), both of which were binuclear structures. Reaction of HL4 with Eu[N(Si Me3)2]2 in 2:1 molar ratio afforded complex { L46Eu3(THF)2}(5) which was trinuclear structure. All of these complexes were characterized by various techniques including the elemental analysis and X-ray single crystal diffraction. Two known complexes 3 and 4({L3Ln[N(TMS)2]THF}2(Ln = Eu(3), Yb(4); HL3 = C6H5CONHC6H3(iPr)2)) were prepared as described in literature.2. The catalytic activities of amidate divalent lanthanide complexes 1-5 for the formation of 2,4-quinazolidinones from CO2 and 2-aminobenzonitriles were tested. The reaction conditions, such as the amount of catalyst loading, additives, reaction time, solvent, temperature and so on, were screened. And the comparison of catalytic activity with different metals and ligands of the complexes were investigated. The result showed that complex 3 has the highest activity and performed well in a relatively wide scope of substrates at atmospheric pressure.3. The catalytic activities of complexes 1-5 for the formation of 5-substituted oxazolidinones from the treatment of aziridines with CO2 were also tested. We screened the reaction conditions such as the amount of catalyst loading, reaction time, solvent, and temperature. And the comparison of catalytic activity with different metals and ligands of the complexes were investigated. The results showed that complex 1 has the highest activity in the transformation and performed well in a relatively wide scope of substrates we synthesized.