Syntheses of Highly Functionalized Metal Complexes as Models of Metal Proteins

合成了一种新的双核配体1，2-双[2-（双（2-吡啶甲基）氨甲基）-6-吡啶基]乙烷（6-HPA），其中两个三（2-吡啶甲基）胺（TPA）单元在6-py位上连接到一个-CH_2CH_2-链上。6-HPA形成二铁（III）配合物[Fe_2（6-HPA）（O）（OH_2）_2]（ClO_4）_4（1），其作为sMMO的功能模型。通过X射线衍射分析确定了化合物1的晶体结构。在稳定的二铁核存在下，1主要催化烯烃与H_2O_2的环氧化反应，得到了高产率和大的转化数，反式-β-甲基苯乙烯得到了91%的反式环氧化物，转化数超过100。在低电离势条件下，烯烃的环氧化产率较高，顺式-β-甲基苯乙烯的环氧化产物为反式环氧化物，表明烯烃发生了单电子氧化。在-40℃的乙腈溶液中，1与2当量H_2O_2反应生成一个绿色产物4。电子吸收数据，490 nm（1130 M·<-1>cm-1<-1>），670（1060）和882（sh，370），CSI MS的主峰在m/z 865处，用H_2·O_2移动到m/z 869<18>，表明4是μ-氧代-μ-过氧二铁（III）。以<18>反式-β-甲基苯乙烯为底物，用<18>H_2^O_2、μ-^<18>O-1、<18>H_2^O、μ-^O_2<18>进行了不同条件下的^O标记实验，探讨了O_2活化机理。在<18><18>Ar气氛下，当<16>H_2^O_2/μ-^<18>O-1（1/1）或（3/1）时，环氧化合物中的μ-^ O-1的掺入率分别为3/1%和17%。结果表明，化合物4中的μ-O和μ-O_2中的O原子是等量地结合到环氧化物中的。4可以通过O-O键的均裂转化为二氧代-μ-氧代二铁（IV），其中三个O原子彼此混杂。

1,2-Bis[2-(bis(2-pyridylmethyl)aminomethyl)-6-pyridyl]ethane (6-HPA) was prepared as a new dinucleating ligand, where two tris(2-pyridylmethyl)amine (TPA) units are attached to a -CH_2CH_2- tether at the 6-py position. 6-HPA forms the diiron(III) complex [Fe_2(6-HPA)(O)(OH_2)_2](ClO_4)_4 (1), which acts as functional models of sMMO. Crystal structure of 1 was determined by X-ray analysis. Given the stable diiron core, 1 catalyzes the predominant epoxidation of the alkene with H_2O_2, where both a high yield and large turnover number were attained; trans-β-methylstyrene gave the trans-epoxide in 91% yield and the turnover number exceeded one hundred. A high epoxide yield for the alkene with low ionization potential and trans-epoxide production from cis-β-methylstyrene indicated that a one-electron oxidation of the alkene had occurred. The radical cation given was partly rearranged from cis to trans. The addition of 2 eq of H_2O_2 to 1 at -40℃ in MeCN generated a green species 4. The electronic absorption data, 490 nm (1130 M^<-1> cm^<-1>), 670 (1060), and 882 (sh, 370), with the main peak of the CSI MS at m/z 865, and a shift to m/z 869 with H_2^<18>O_2 shows that 4 is a μ-oxo-μ-peroxodiiron(III). ^<18>O-labeling experiments using trans-β-methylstyrene as a substrate were carried out under various conditions using H2^<18>O_2, μ-^<18>O-1, H_2^<18>O, and ^<18>O_2 to gain some insights into the O_2-activation mechanism. ^<18>O was incorporated into 94% of the epoxide with H_2^<18>O_2/1 (10/1, mol/mol) under Ar and into 31 or 17% of the epoxide with H_2^<16>O_2/μ-^<18>O-1 (1/1) or (3/1) under Ar. The data clearly showed that O-atoms of μ-O and μ-O_2 in 4 were incorporated equivalently into the epoxide. 4 may be converted to a dioxo-μ-oxodiiron(IV) via homolytic scission of the O-O bond, where three O-atoms scramble one another.