SYNTHESIS OF DIIRON COMPLEXES AS EFFICIENT CATALYSTS FOR OXIDATIVE ALKANE-HYDROXYLATION

合成了2，2 ′-二[二（2-吡啶基）甲基]-6，6 ′-亚乙基二吡啶（L^1）和3，3-二-2-吡啶基丙酸（L^2）。这些配体自发地形成μ-氧代-二-间-乙酸基二铁（III）配合物[Fe_2（O）（OAc）_2（L^1）]（X）_2（x=ClO_4 1a和CF_3SO_3 1b）和[Fe_2（O）（OAc）_2（L^2）_2]（2），通过与三价铁离子和乙酸钠的反应，这些二铁配合物作为可溶性甲烷单加氧酶（sMMO）的模型发挥作用。其在甲烷氧化菌中催化甲烷羟基化为甲醇。以间氯过苯甲酸（m-CPBA）为氧化剂时，1催化环己烷、甲基环己烷、金刚烷、正构烷烃和正构烷烃的氧化反应。环己烷与1的氧化反应的催化转化数和转化频率分别大于1000和100次/min。1的转换数是环己烷/（四苯基卟啉）铁（III）/m-CPBA体系的10倍。化合物2催化相同的反应。 关于我们 2催化的反应比1催化的反应快得多。羧酸根离子的配位使2呈电中性，提高了2在非极性溶剂中的溶解度，使烷烃的功能化反应快速有效; 1b在乙腈/环己烷中的浅棕色溶液加入H2 O2后变为紫色。紫色溶液的电子吸收光谱在约40 nm处有两个吸收带。500（λ：1000）和600（λ：1000 M·<-1>cm ~ 2<-1>）nm，表明形成了过氧二铁（Ⅲ）配合物[Fe_2（O）（Ac）（O_2）（L ~ 1）]（CF_3SO_3）（3）。3在乙腈/环己烷中的半衰期为79 min，表明3是热稳定的。为了分离3，将紫色溶液浓缩至干。分离的3的FAB质谱在m/z：739，707和679处显示出相对较强的母峰，分别归属于[Fe_2（O）（OAc）（O_2）（L^1）] ^+，[Fe_2（O）（OAc）（L^1）] ^+和[Fe_2（O）（O_2）（L^1）] ^+。这些数据合理地解释了过氧二铁（III）络合物3的形成。少

2,2'-Bis [di (2-pyridyl) methyl] -6,6'-ethylenedipyridine (L^1) and 3,3-di-2-pyridylpropanoic acid (L^2) have been synthesized. These ligands form spontaneously mu-oxo-di-m-acetatodiiron (III) complexes, [Fe_2 (O) (OAc) _2 (L^1)] (X) _2 (x=ClO_4 1a and CF_3SO_3 1b) and [Fe_2 (O) (OAc) _2 (L^2) _2] (2), by the reaction with iron (III) ion and sodium acetate.These diiron complexes funciton as a model of soluble methane monooxygenase (sMMO) which catalyzes the hydroxylation of methane to methanol in methanotroph. When m-chloroperbenzoic acid (m-CPBA) is used as oxidant, 1 catalyzes the oxygenation of cyclohexane, methylcyclohexane, adamantane, n-alkanes, and ethylbenzene. The catalytic turnover number and the turnover frequency for the oxygenaiton of cyclohexane with 1 are larger than 1000 and 100 cycles/min, respectively. The turnover number of 1 is ten-fold larger than that of a cyclohexane/ (tetraphenyl-porphynato) iron (III) /m-CPBA system. The compound 2 catalyzes the same reaction. … More The reaction ctatlyzed by 2 is much faster than that of 1. The coordination of carboxylate ion makes 2 electrically neutral and enhances the solubility of 2 in non-polar solvent, leading to the rapid and efficient alkane functionalization.A pale brown solution of 1b in CH_3CN/cyclohexane turns purple by the addition of H_2O_2. The electronic absorption spectrum of the purple solution shows two bands at ca. 500 (epsilon : 1000) and 600 (epsilon : 1000 M^<-1>cm^<-1>) nm, suggesting the formation of a peroxodiiron (III) complex [Fe_2 (O) (OAc) (O_2) (L^1)] (CF_3SO_3) (3). A half life time of 3 in CH_3CN/cyclohexane is 79 min, showing that 3 is thermally quite stable. In order to isolate 3, the purple solution is concentrated to dryness. FAB Mass spectrum of the isolated 3 shows relatively strong parent peaks at m/z : 739,707, and 679, which are assignable to [Fe_2 (O) (OAc) (O_2) (L^1)] ^+, [Fe _2 (O) (OAc) (L^1)] ^+, and [Fe_2 (O) (O_2) (L^1)] ^+, respectively. These data reasonably explain the formation of the peroxodiiron (III) complex 3. Less