Synthesis and Reactions of a Redox-Active α‑Diimine Aluminum Complex

The reaction of the ene-diamine LH2 (L = [ArNC­(Me)­C­(Me)­NAr]2–, Ar = 2,6-iPr2C6H3) with AlMe3 and AlEt3 yielded the aluminum dimethyl complex (LH)­AlMe2 (1) and the radical (L•)­AlEt2 (2; L• = [ArNC­(Me)­C­(Me)­NAr]•–), respectively. Treatment of 2 with O2 and TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) led to hydrogen abstraction from the methyl group at the ligand backbone to give the diamagnetic species (L*)­AlEt2 (3; L* = [ArNC­(Me)­C­(CH2)­NAr]−) and (L*)­Al­(TEMPO)­(Et) (4). In contrast, the reaction of 2 with iodine resulted in the iodination of the Al–C bonds and yielded the radical (L•)­AlI2 (5). Reaction of 2 with BCl3 led to electron transfer between the α-diimine radicals with the formation of the aluminum cation [(L0)­AlCl2]+[AlCl4]− (6; L0 = ArNC­(Me)­(Me)­CNAr) and the diazaborole LBCl (7). The structures of compounds 2, 3, and 7 have been determined by X-ray single-crystal diffraction, and the paramagnetic species 2 has been characterized by EPR measurements.烯二胺配体LH₂（其中L = [ArNC(Me)C(Me)NAr]²⁻，Ar = 2,6-二异丙基苯基(2,6-iPr₂C₆H₃)）与三甲基铝(AlMe₃)、三乙基铝(AlEt₃)分别反应，得到二甲基铝配合物(LH)AlMe₂（化合物1）和自由基物种(L•)AlEt₂（化合物2；其中L• = [ArNC(Me)C(Me)NAr]•⁻）。将化合物2与氧气(O₂)及2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)反应，可从配体骨架的甲基上发生夺氢反应，生成反磁性物种(L*)AlEt₂（化合物3；L* = [ArN=C(Me)C(CH₂)NAr]⁻）与(L*)Al(TEMPO)(Et)（化合物4）。与之相对，化合物2与碘单质反应会引发铝-碳键的碘化反应，得到自由基物种(L•)AlI₂（化合物5）。化合物2与三氯化硼(BCl₃)反应时，α-二亚胺自由基之间发生电子转移，生成铝阳离子盐[(L⁰)AlCl₂]⁺[AlCl₄]⁻（化合物6；其中L⁰ = ArN=C(Me)(Me)C=NAr）以及二氮杂硼咯配合物LBCl（化合物7）。已通过X射线单晶衍射确定了化合物2、3和7的晶体结构，并通过电子顺磁共振(Electron Paramagnetic Resonance, EPR)测试对顺磁性物种2进行了表征。