Two ternary ligands consisting of two 2,2′:6′,2′′-terpyridines and one N4-quadridentate μ2,η2-bridging ligand were synthesized. The N4 bridge is 1,4-bis(2-pyridyl)phthalazine in ligand 1, and 3,6-bis(2-pyridyl)pyridazine in ligand 2. Two Co(II) dinuclear complexes [(1)Co2(μ-OH)]3+ and [(2)Co2(μ-OH)]3+, and one Ni(II) dinuclear complex [(1)Ni2(μ-Cl)]3+ were obtained. In the crystal structures of [(1)Co2(μ-OH)]3+ and [(1)Ni2(μ-Cl)]3+, two pyridine rings are twisted around the pyridine–phthalazine bonds to avoid steric repulsion between the hydrogen atoms. The pyridine rings also showed a significant tilt from the octahedral coordination plane, which causes the large positive shift of the first reduction potentials. Upon the addition of a proton, the cobalt dinuclear complexes can release one cobalt ion selectively, and the dinuclear complexes can be easily restored by the addition of a tertiary amine.
我们合成了由两个 2,2′:6′,2′′-三
吡啶和一个 N4-四叉μ2,η2-桥
配体组成的两个三元
配体。
配体 1 中的 N4 桥是 1,4-双(2-
吡啶基)
酞嗪,
配体 2 中的 N4 桥是 3,6-双(2-
吡啶基)
哒嗪。得到了两个 Co(II)双核配合物 [(1)Co2(μ-OH)]3+ 和 [(2)Co2(μ-OH)]3+ 以及一个 Ni(II)双核配合物 [(1)Ni2(μ-Cl)]3+ 。在[(1)Co2(μ-OH)]3+和[(1)Ni2(μ-Cl)]3+的晶体结构中,两个
吡啶环围绕
吡啶-
酞嗪键扭曲,以避免氢原子之间的立体排斥。
吡啶环还显示出明显的八面体配位面倾斜,这导致了第一还原电位的大幅正移。加入一个质子后,
钴双核配合物可以选择性地释放出一个
钴离子,加入一个叔胺后,双核配合物很容易恢复原状。