Schiff碱双核配合物的磁性及模拟甲烷单加氧酶催化性能的研究

存在于生命体中的甲烷单加氧酶是一种双金属单加氧酶，其结构及催化作用机制目前还不十分清楚．为了模拟甲烷单加氧酶的催化作用，探讨甲烷单加氧酶中两个金属离子间是否存在协同作用，本文按前文方法合成了双N，N’-亚乙基-2，2’-(苯亚甲基)二(3，4-二甲基吡咯-5-醛缩亚胺)]合单金属配合物MH2L(1～7)及双金属配合物MnML(8-14)(结构见Scheme 1)．

Magnetic and Biomimetic Catalytic Properties of New Schiff Base Dinuclear Complexes as Model Compounds of Methane Monooxygenase

This paper reports the biomimetic catalytic properties of new Schiff base mononuclear complexes MH2LM = Mn(Ⅱ), Fe(Ⅲ)Cl, Cr(Ⅲ)Cl, Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Zn(Ⅱ); L=bis N,N'-ethylene-2,2'-(phenylmethylene)bis(3,4-dimethylpyrrole-5-aldimino)] and dinuclear complexes MnMLM=Mn(Ⅱ), Fe(Ⅲ)Cl, Cr(Ⅲ)Cl, Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Zn(Ⅱ)] for studying the monooxygenation of cyclohexane with PhIO and magnetic properties of the dinuclear complexes. The investigation of the magnetic properties(4—300 K) of the dinuclear complexes revealed that their antiferromagnetic spin exchange with J varied from -10.49 to -0.482 cm -1 except MnZnL, and antiferromagnetic spin exchange decreased in the order: Mn(Ⅱ)-Cu(Ⅱ)>Mn(Ⅱ)-Ni(Ⅱ)>Mn(Ⅱ)-Mn(Ⅱ)>Mn(Ⅱ)-Fe(Ⅲ)>Mn(Ⅱ)-Co(Ⅱ)>Mn(Ⅱ)-Cr(Ⅲ). The yield determination of monooxygenation of cyclohexane indicated that the catalytic reactivity of the dinuclear complex was better than that of the corresponding mononuclear complex, so we supposed that there was some cooperative action between the two metals in these dinuclear complexes. It was found that the cooperation lay in the decreasing order: Mn-Fe>Mn-Cr>Mn-Cu>Mn-Mn>Mn-Co>Mn-Ni>Mn-Zn. It seems that this cooperation increased with the increase of the number of unpaired d electrons and the magnetic exchange between the two metals in these dinuclear complexes.