화학공학소재연구정보센터
Inorganic Chemistry, Vol.58, No.24, 16559-16573, 2019
Synthesis and epsilon-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand
The synthesis of electron-deficient gallium- and aluminum-centered species containing a redox-active dpp-Bian ligand (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) is described. The reaction of digallane [(dpp-Bian)Ga-Ga(dpp-Bian)] with [Ph3C][PF6] or AgPF6 resulted in polyoxidized species [(dpp-Bian)GaF2](2) (1), [(dpp-Bian)H-2][PF6] (2), and [(dpp-Bian)GaF(O2PF2)](2) (3). The reaction of digallane with B(C6F5)(3) led to electron-deficient gallylene [(dpp-Bian)GaB(C6F5)(3)] 4 of a dpp-Bian radical anion. The soft oxidation of digallane with tosyl cyanide gave the trinuclear cationic species [(dpp-Bian)Ga(Tos)(3)Ga(Tos)(3)Ga(dpp-Bian)][Ga(CN)(4)] (5) containing dpp-Bian radical anions. The reaction of [(dpp-Bian)AlEt2] with 1 equiv of [Ph3C][B(C6F5)(4)] resulted in the cationic complex [(dpp-Bian)A1Et(2)][B(C6F5)(4)] (6) of neutral dpp-Bian, while the treatment of [(dpp-Bian)AlEt(Et2O)] with 1 equiv of [Ph3C][B(C6F5)(4)] resulted in the compound Rdpp-Bian)AlEt(Et2O)][B(C6F5)(4)] (7) of a dpp-Bian radical anion. The reaction of diethylaluminum derivative [(dpp-Bian)AlEt2] with 1 equiv of B(C6F5)(3) gave the cationic complex [{(dpp-Bian)AIEt}(2)F] [EtB(C6F5)(3)] (8) containing radical-anion dpp-Bian ligands. The paramagnetic compounds 1, 2, 4, 5, 7, and 8 were characterized by electron paramagnetic resonance spectroscopy, and the diamagnetic complex 6 was characterized by NMR spectroscopy. The molecular structures of 1-6 and 8 were established by single-crystal X-ray diffraction analysis. Compounds 4 and 6-8 were found to be active initiators for immortal ring-opening polymerization of epsilon-caprolactone.