Studies on the Preparation of Dinuclear Transition Metal Complexes, and the Activation-states of Small Molecules and the Magnetic Interactions involved therein

(1)双核铁络合物：已知的双核混价铁(II，III)中心参与了半甲基氯氰菊酯和粉红色子宫铁蛋白等铁蛋白的形成。我们设计了两个新的双核配体，2，6-双[双(2-吡啶甲基)和2-benzimidazolylmethyl)aminomethyl]-4-methylphenol，，具有双边双对称结构。新合成了含有上述配体和羧酸根离子的双核铁(II，II)、(II，III)和(III，III)配合物。从电子、电子自旋共振、穆斯堡尔谱和混合磁化率的结果发现：(1)铁(II，III)络合物比铁(II，II)和(III，III)络合物更稳定，(2)铁(II，III)络合物属于所谓的II类混价络合物；二核和四核锰配合物：绿色植物光系统II(PS II)中的双核和四核锰中心对水催化氧化成分子氧(2H_2O-&GT；O_24H^4E)起着至关重要的作用。我们新合成了双核锰(II，II)，(II，III)，(III，IV)和(IV，IV)与2，6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol.的配合物四核锰(II，III，III，II)与三(2-吡啶甲基)胺(N_4-py)的配合物，用X-射线单晶衍射法确定了它们的结构。在这些络合物中，N_4-Py络合物显示出催化氧化水的可能性，但我们还没有得到足够好的证据。这方面的研究具有很大的发展潜力。(3)成功地分离了可逆地与分子氧结合的双核钴(II，II)配合物。以线性氰离子为桥联配体的双核铬(III，III)配合物具有较弱的反铁磁性相互作用。

(1) Dinuclear Iron Complexes: dinuclear mixed-valence iron(II,III) centers have been known to be involved in the iron proteins such as semi-methemerythrin and pink uteroferrin. We designed two new dinucleating ligands, 2,6- bis[bis(2-pyridylmethyl and 2-benzimidazolylmethyl)aminomethyl]-4-methylphenol, which have bilaterally bisymmetric structures. The dinuclear iron(II,II), (II,III) and (III,III) complexes containing the above ligands and carboxylate ions were newly prepared. From the results of electronic, ESR and Mossbauer spectra, and mignbtic susceptibilities, it was found that (1) the iron(II,III) complex is much more stabilized than the iron(II,II) and (III,III) complexes; (2) the iron(II,III) complex belongs to the so-called Class II mixed-valence complex; and (3) a weak antiferromagnetic interaction it exerted between the two iron ions.(2) Dinuclear and Tetranuclear Manganese Complexes: the dinuclear and tetranuclear manganese centers in photosystem II (PS II) in green plants have been shown to play a-n essential role for the catalytic oxidation of water to molecular oxygen (2H_2O -> O_2 + 4H^+ + 4e ). We newly prepared the dinuclear manganese(II,II), (II,III), (III,IV), and (IV,IV) complexes with 2,6 bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol. and the tetranuclear manganese(II,III,III,II) complexes with tris(2-pyridylmethyl)amine (N_4-py).The structures of the complexes were clarified by means of X-ray crystallography. Among these complexes, the N_4-py complex showed the sign of possibility of the catalytic oxidation of water, but we have not yet obtained good enough evidences. The study in this category has great potentialities for future level opment.(3) We succeeded in isolating the dinuclear cobalt(II,II) complexes which bind reversibly molecular oxygen. A weak antiferromagnetic interaction was recognized in the dinuclear chromium(III,III) complexes which contain a linear cyanide ion as the bridging ligand.