Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
Inorg Chem. 2011 May 2;50(9):3866-87. doi: 10.1021/ic1020324. Epub 2011 Mar 31.
To model the heterodinuclear active sites in plant purple acid phosphatases, a mononuclear synthon, [Fe(III)(H(2)IPCPMP)(Cl(2))][PF(6)] (1), has been generated in situ from the ligand 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)amino methyl)-4-methylphenol (IPCPMP) and used to synthesize heterodinuclear complexes of the formulas [Fe(III)M(II)(IPCPMP)(OAc)(2)(CH(3)OH)][PF(6)] (M = Zn (2), Co (3), Ni (4), Mn (5)), [Fe(III)Zn(II)(IPCPMP)(mpdp)][PF(6)] (6) (mpdp = meta-phenylene-dipropionate), and [Fe(III)Cu(II)(IPCPMP) (OAc)}(2)(μ-O)][PF(6)] (7). Complexes 2-4, 6, and 7 have been crystallographically characterized. The structure of 6 is a solid state coordination polymer with heterodinuclear monomeric units, and 7 is a tetranuclear complex consisting of two heterodinuclear phenolate-bridged Fe(III)Cu(II) units bridged through a μ-oxido group between the two Fe(III) ions. Mössbauer spectra confirm the presence of high spin Fe(III) in an octahedral environment for 1, 3, and 5 while 2 and 4 display relaxation effects. Magnetic susceptibility measurements indicate weak antiferromagnetic coupling for 3, 4, and 5 and confirm the assignment of the metal centers in 2-5 as high spin Fe(III)-M(II) (M = Zn, Co (high spin), Ni (high spin), Mn (high spin)). Complexes 2-5 are intact in acetonitrile solution as indicated by IR spectroscopy (for 2-4) and electrospray ionization mass spectrometry (ESI-MS) but partly dissociate to hydroxide species and a mononuclear complex in water/acetonitrile solutions. UV-vis spectroscopy reveal pH-dependent behavior, and species that form upon increasing the pH have been assigned to μ-hydroxido-bridged Fe(III)M(II) complexes for 2-5 although 2 and 3 is further transformed into what is propsed to be a μ-oxido-bridged tetranuclear complex similar to 7. Complexes 2-5 enhance phosphodiester cleavage of 2-hydroxy-propyl-p-nitrophenyl phosphate (HPNP) and bis(2,4-dinitrophenyl)phosphate (BDNPP), but the reactivities are different for different complexes and generally show strong pH dependence.
为了模拟植物紫色酸性磷酸酶中的异双核活性位点，我们原位生成了单核合成物 [Fe(III)(H(2)IPCPMP)(Cl(2))][PF(6)]（1），其中 IPCPMP 是 2-(N-异丙基-N-((2-吡啶基)甲基)氨甲基)-6-(N-(羧甲基)-N-((2-吡啶基)甲基)氨基甲基)-4-甲基苯酚。使用该单核合成物来合成了异双核配合物，其化学式为 [Fe(III)M(II)(IPCPMP)(OAc)(2)(CH(3)OH)][PF(6)]（M = Zn（2），Co（3），Ni（4），Mn（5）），[Fe(III)Zn(II)(IPCPMP)(mpdp)][PF(6)]（6）（mpdp = 间苯二丙酸）和 [Fe(III)Cu(II)(IPCPMP)(OAc)}_2(μ-O)][PF(6)]（7）。这些配合物均已通过晶体学进行了表征。6 的结构是一种固态配位聚合物，具有异双核单体单元，而 7 是一种由两个异双核的 phenolate 桥接的 Fe(III)Cu(II)单元组成的四核配合物，通过两个 Fe(III)离子之间的 μ-氧桥连接。穆斯堡尔光谱证实 1、3 和 5 中存在高自旋 Fe(III)在八面体环境中，而 2 和 4 则显示出弛豫效应。磁导率测量表明 3、4 和 5 之间存在弱反铁磁耦合，并证实 2-5 中金属中心的分配为高自旋 Fe(III)-M(II)（M = Zn、Co（高自旋）、Ni（高自旋）、Mn（高自旋））。2-5 在乙腈溶液中是完整的，这可以通过红外光谱（2-4）和电喷雾电离质谱（ESI-MS）来证明，但在水/乙腈溶液中会部分解离为氢氧化物和单核配合物。紫外可见光谱揭示了 pH 依赖性行为，并且随着 pH 值的增加形成的物质被分配到μ-羟基桥接的 Fe(III)M(II)配合物，用于 2-5，尽管 2 和 3 进一步转化为被提议为类似于 7 的μ-氧桥接的四核配合物。配合物 2-5 增强了 2-羟基丙基对硝基苯磷酸盐（HPNP）和双（2,4-二硝基苯基）磷酸酯（BDNPP）的磷酸二酯断裂，但不同配合物的反应性不同，并且通常表现出强烈的 pH 依赖性。
