Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes
Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes
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DOI：
10.1021/ic981091s
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发表时间：
1999-03-08
影响因子：
4.6
通讯作者：
Karlin, KD
中科院分区：
文献类型：
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作者：
Corsi, DM;Murthy, NN;Karlin, KD
已知一系列小分子，例如氰化物，结合和/或抑制血红素-铜氧化酶的活性位点。因此，模型研究的目的是阐明配体结合模式及其对衍生复合物光谱性质的后续影响。本文描述了两种含有Fe-CN-Cu部分的化合物[（py）（F-8-TPP）Fe-III-CN-Cu-II（TMPA）]（2+）（5）和[（F-8-TPP）Fe-III-（CN）（2）-{Cu-II（TMPA）}（2）]（3+）（6）[py =吡啶，TMPA =三（2-吡啶基甲基）胺，和（F-8-TPP）=四（2，6-二氟苯基）卟啉（2-）]的分离和表征。[Cu-II（TMPA）（CH3CN）]（CIO4）（2）和[（py）（F-8-TPP）Fe（II）（CN）]（3）反应生成5，而6由[Cu-II（TMPA）（CN）] PF6（2-（PF6））和[（F-8-TPP）Fe-III（PF6）]（4）组合形成。配合物2-（PF 6）属于正交晶系，空间群为Iba 2，晶胞参数a = 17.2269（5）埃，B = 17.3143（4）埃，c = 14.4971（4）埃，Z = 8，5-（Sb/P）F-6配合物（1.5）（CLO4）（0.5）在正交空间群P222中获得，a = 17.9541（2）埃，B = 20.5359（1）埃，c = 21.2023（2）埃，Z = 4，6-（PF_6）（3）晶体属单斜晶系，空间群P_2（1）/c，a = 15.318（4）埃，B = 33.921（2）埃，c = 19.649（6）埃，β = 109.69（2）4，Z = 4。化合物5具有低自旋铁（III）中心，通过氰化物桥连到铜。铁氰化物矢量略微偏离线性（174.6（5）度）。铜（II）离子由TMPA N-供体原子和氰化物碳原子五配位。Cu（TMPA）部分围绕氰化物-铜矢量以163.8（5）度的角度弯曲。化合物6具有一个低自旋铁（III）原子轴向配位的两个氰化物配位体由三角配位的[Cu（TMPA）]部分在任何一侧封端。[Cu（1）（TMPA）]单元稍微扭曲（角Cu1-N = C = 168度），而[Cu（2）（TMPA）]单元相对于氰化物-铁矢量以接近线性的方式配位（角Cu2-N = C4 = 175度）。5和6的H-1和H-2 NMR光谱证实了这些铁络合物的低自旋性质（分别在-11.1和-8 ppm处发现吡咯共振）。NMR数据以及观察到的溶液磁矩（对于5，mu（B）= 2.7;对于6，mu（B）= 3.4）表明顺磁性金属离子之间的铁磁耦合。这引起了5和6中Cu（II）的电子弛豫速率的增强，从而允许观察到尖锐和低场偏移的TMPA配体质子信号。
A range of small molecules, such as cyanide, are known to bind and/or inhibit the active site of the heme-copper oxidase enzymes. As such, model studies are aimed at elucidating Ligand binding modes and their subsequent impact on spectroscopic properties of derived complexes. We describe here the isolation and characterization of two compounds containing the Fe-CN-Cu moiety, [(py)(F-8-TPP)Fe-III-CN-Cu-II(TMPA)](2+) (5) and [(F-8-TPP)Fe-III-(CN)(2)-{Cu-II(TMPA)}(2)](3+) (6) [py = pyridine, TMPA = tris(2-pyridylmethyl)amine, and (F-8-TPP) = tetrakis(2,6-difluorophenyl)porphyrinate(2-)]. [Cu-II(TMPA)(CH3CN)](CIO4)(2) and [(py)(F-8-TPP)Fe(II)(CN)] (3) react to yield 5, while 6 is formed by combination of [Cu-II(TMPA)(CN)]PF6 (2-(PF6)) and [(F-8-TPP)Fe-III(PF6)] (4). Complex 2-(PF6) crystallizes in the orthorhombic space group Iba2 with a = 17.2269(5) Angstrom, b = 17.3143(4) Angstrom, and c = 14.4971(4) Angstrom, Z= 8, complex (5-(Sb/P)F-6)(1.5)(CLO4)(0.5) was obtained in the orthorhombic space group P222 with a = 17.9541(2) Angstrom, b = 20.5359(1) Angstrom, and c = 21.2023(2) Angstrom, Z = 4, and 6-(PF6)(3) crystallized in the monoclinic space group P2(1)/c with a = 15.318(4) Angstrom b = 33.921(2) Angstrom, and c = 19.649(6) Angstrom, beta = 109.69(2)4 and Z = 4. Compound 5 possesses a low-spin iron(III) center, bridged via cyanide to copper. The iron-cyanide vector deviates slightly from linearity (174.6(5)degrees). The copper(II) ion is five-coordinated by the TMPA N-donor atoms and the cyanide carbon atom. The Cu(TMPA) moiety is bent with an angle of 163.8(5)degrees around the cyanide-copper vector. Compound 6 possesses a low-spin iron(III) atom axially coordinated by two cyanide ligands capped on either side by trigonally coordinated [Cu(TMPA)] moieties. The [Cu(1)(TMPA)] unit is twisted somewhat (angle Cu1-N=C = 168 degrees), whereas the [Cu(2)(TMPA)] unit is coordinated in a nearly linear fashion with respect to the cyanide-iron vector (angle Cu2-N=C4 = 175 degrees). H-1 and H-2 NMR spectroscopy on 5 and 6 confirmed the low-spin nature of these iron complexes (pyrrole resonance found at -11.1 and -8 ppm, respectively). The NMR data as well as observed solution magnetic moment (mu(B) = 2.7 for 5; mu(B) = 3.4 for 6) suggest ferromagnetic coupling between the paramagnetic metal ions. This gives rise to an enhancement of the electronic relaxation rate for Cu(II) in both 5 and 6 allowing for the observation of the sharp and downfield shifted TMPA ligand proton signals.