Isolation and crystal structure of a peroxo-bridged heme-copper complex
Isolation and crystal structure of a peroxo-bridged heme-copper complex
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DOI：
10.1002/anie.200351415
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发表时间：
2003-01-01
影响因子：
16.6
通讯作者：
Maeda, Y
中科院分区：
文献类型：
--
作者：
Chishiro, T;Shimazaki, Y;Maeda, Y
2789安徽。化学。内部艾德2003，42,2788-2791 www.安格万特。Org2003 Wiley-VCH Verlag GmbH&Co.KGaA，Weinheim卟啉配合物(M=TiIII，[10]或MnIII[12])，与过氧铁(III)卟啉的EXAFS结构一致。[14B]TPA-Cu-OO单元的结构类似于由[(μ)CuI(CH3CN)]+(TMPA=三(2-吡啶甲基)胺)和二氧衍生的反式(TMPA)双铜(II)配合物的结构。[15]铜离子由三个吡啶、氮原子与扭曲的三角双锥构型配位过氧基配体的一个叔氮原子和一个氧原子。铜(1)从N(1)、N(2)、N(3)三角平面移位0.319(2)，远离叔氮N(4)朝向过氧基的O(2)。铜(1)-O(2)键长(103.0(5))和铜(1)-O(2)-O(3)角(103.0(4)8)与反式(μ-1，2-过氧基)二铜(II)络合物相近。过氧络合物2在4K下ESR失活，磁化率在10~300K之间测量，测得有效磁矩为4.65MB，在此温度范围内与温度无关。该磁矩与唯一自旋值S=2(μEf=4.90μB)相一致，因此，2被指定为顺磁性物种，总体S=2自旋态。2(77K，零场)的穆斯堡尔谱显示一个尖锐的四极偶极子，其参数(ΔEq=1.17 mm S±1，d=0.56 mm S±1)是高自旋FeIII化合物(见辅助信息)的典型参数，并与过氧键合铁(III)-卟啉配合物的结果很好地一致。基于这些结果，铁离子具有高自旋d5组态(S=5/2)，并以反铁磁方式与铜(II)离子(S=1/2)强烈耦合。这种金属离子之间的强相互作用是由桥接的过氧基配体介导的。综上所述，我们合成并表征了一个过氧桥联的铁-铜配合物2。元素分析和多种光谱方法证实了2的成功分离。2的X-射线结构分析表明，Fe-O2-Cu部分具有μ-η2：η1配位模式。据我们所知，这是确定过氧桥联异双核配合物结构的第一个例子。此外，这是第一个具有侧向过氧基的“铁”-卟啉配合物的X射线结构。[14]配合物2是一个自旋态为S=2的顺磁性物种，因为桥接过氧基的配体介导了高自旋铁(III)和铜(II)离子之间的强烈反铁磁性耦合。2的进一步研究正在我们实验室进行中。
2789 Angew. Chem. Int. Ed. 2003, 42, 2788–2791 www. angewandte. org 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim phyrin complexes (M= TiIII,[10] or MnIII [12]) and is consistent with the EXAFS structure of peroxo–iron (iii) porphyrin.[14b] The structure of the TPA-Cu-OO unit is similar with that of the trans-(μ-1, 2-peroxo) dicopper (ii) complex derived from [(TMPA) CuI (CH3CN)]+(TMPA= tris (2-pyridylmethyl)-amine) and dioxygen.[15] The copper ion is pentacoordinated with a distorted trigonal-bipyramidal geometry by the three pyridine nitrogen atoms, the one tertiary nitrogen atom and the one oxygen atom of the peroxo ligand. Cu (1) is displaced 0.319 (2) out of the N (1), N (2), N (3) trigonal plane away from the tertiary nitrogen N (4) toward O (2) of the peroxo ligand. The Cu (1)-O (2) bond length (1.915 (5)) and the Cu (1)-O (2)-O (3) angle (103.0 (4) 8) are close to those of the trans-(μ-1, 2-peroxo) dicopper (ii) complex.[15] Evidence that the peroxo ligand bridges the iron and the copper ions is also obvious from magnetic studies. The peroxo complex 2 is ESR inactive at 4 K. The magnetic susceptibility of 2 was measured from 10 to 300 K. The determined effective magnetic moment is 4.65 mB and temperature independent within this temperature range. This magnetic moment is consistent with a spin-only value of S= 2 (μeff= 4.90 μB), therefore, 2 is assigned as a paramagnetic species with an overall S= 2 spin state. The Mössbauer spectrum of 2 (77 K, zero field) showed a sharp quadrupole doublet with parameters (ΔEq= 1.17 mm sÀ1, d= 0.56 mm sÀ1) typical for highspin FeIII compound (see Supporting Information), and is in good agreement with those of peroxo-bound iron (iii)-porphyrin complexes.[5e, 14c] Based on these results, the iron ion has a high-spin d5 configuration (S= 5/2), and is strongly coupled with the copper (ii) ion (S= 1/2) in an antiferromagnetic fashion. This strong interaction between the metal ions is mediated by the bridging peroxo ligand. In conclusion, we synthesized and characterized a peroxobridged iron-copper complex 2. The successful isolation of 2 was confirmed by the elemental analysis and various spectroscopic methods. The X-ray structure analysis of 2 revealed that the Fe–O2–Cu moiety has a μ-η2: η1 coordination mode. To the best our knowlege, this is the first example of the structure determination of a peroxo-bridged heterodinuclear complex. Further, this is the first X-ray structure of an “iron”-porphyrin complex with a side-on peroxo ligand.[14] Complex 2 is a paramagnetic species with a spin state of S= 2, as the bridging peroxo ligand mediates the strong antiferromagnetic coupling between the high-spin iron (iii) and the copper (ii) ions. Further studies of 2 are in progress in our laboratory.