亚硝酰铁（III）卟啉酸盐：卟啉核心构象与FeNO几何结构。有何关联？

Nitrosyliron(III) porphyrinates: porphyrin core conformation and FeNO geometry. Any correlation?

作者信息

Ellison Mary K, Schulz Charles E, Scheidt W Robert

机构信息

Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.

出版信息

J Am Chem Soc. 2002 Nov 20;124(46):13833-41. doi: 10.1021/ja0207145.

DOI:10.1021/ja0207145

PMID:12431114

Abstract

The synthesis, structural, and spectroscopic characterization of (nitrosyl)iron(III) porphyrinate complexes designed to have strongly nonplanar porphyrin core conformations is reported. The species have a nitrogen-donor axial ligand trans to the nitrosyl ligand and display planar as well as highly nonplanar porphyrin core conformations. The systems were designed to test the idea, expressly discussed for the heme protein nitrophorin (Roberts, et al. Biochemistry 2001, 40, 11327), that porphyrin core distortions could lead to an unexpected, bent geometry for the FeNO group. For [Fe(OETPP)(1-MeIm)(NO)]ClO(4).C(6)H(5)Cl (H(2)OETPP = octaethyltetraphenylporphyrin), the porphyrin core is found to be severely saddled. However, this distortion has little or no effect on the geometric parameters of the coordination group: Fe-N(p) = 1.990(9) A, Fe-N(NO) = 1.650(2) A, Fe-N(L) = 1.983(2) A, and Fe-N-O = 177.0(3) degrees. For the complex [Fe(OEP)(2-MeHIm)(NO)]ClO(4).0.5CH(2)Cl(2) (H(2)OEP = octaethylporphyrin), there are two independent molecules in the asymmetric unit. The cation denoted Fe(OEP)(2-MeHIm)(NO)(pla) has a close-to-planar porphyrin core. For this cation, Fe-N(p) = 2.014(8) A, Fe-N(NO) = 1.649(2) A, Fe-N(L) = 2.053(2) A, and Fe-N-O = 175.6(2) degrees. The second cation, Fe(OEP)(2-MeHIm)(NO)(ruf), has a ruffled core: Fe-N(p) = 2.003(7) A, Fe-N(NO) = 1.648(2) A, Fe-N(L) = 2.032(2) A, and Fe-N-O = 177.4(2) degrees. Thus, there is no effect on the coordination group geometry caused by either type of nonplanar core deformation; it is unlikely that a protein engendered core deformation would cause FeNO bending either. The solid-state nitrosyl stretching frequencies of 1917 cm(-)(1) for [Fe(OEP)(2-MeHIm)(NO)]ClO(4) and 1871 cm(-)(1) for [Fe(OETPP)(1-MeIm)(NO)]ClO(4) are well within the range seen for linear Fe-N-O groups. Mössbauer data for [Fe(OEP)(2-MeHIm)(NO)]ClO(4) confirm that the ground state is diamagnetic. In addition, the quadrupole splitting value of 1.88 mm/s and isomer shift (0.05 mm/s) at 4.2 K are similar to other (nitrosyl)iron(III) porphyrin complexes with linear Fe-N-O groups. Crystal data: [Fe(OETPP)(1-MeIm)(NO)]ClO(4).C(6)H(5)Cl, monoclinic, space group P2(1)/c, Z = 4, with a = 12.9829(6) A, b = 36.305(2) A, c = 14.0126(6) A, beta = 108.087(1) degrees; [Fe(OEP)(2-MeHIm)(NO)]ClO(4).0.5CH(2)Cl(2), triclinic, space group Ponemacr;, Z = 4, with a = 14.062(2) A, b = 16.175(3) A, c = 19.948(3) A, alpha = 69.427(3) degrees, beta = 71.504(3) degrees, gamma = 89.054(3) degrees.

摘要

报道了具有强非平面卟啉核心构象的（亚硝酰基）铁（III）卟啉配合物的合成、结构和光谱表征。这些物种具有与亚硝酰基配体反位的氮供体轴向配体，并呈现平面以及高度非平面的卟啉核心构象。设计这些体系是为了检验血红素蛋白嗜硝蛋白（罗伯茨等人，《生物化学》，2001年，40卷，11327页）明确讨论的观点，即卟啉核心畸变可能导致FeNO基团出现意想不到的弯曲几何形状。对于[Fe(OETPP)(1-MeIm)(NO)]ClO₄·C₆H₅Cl（H₂OETPP = 八乙基四苯基卟啉），发现卟啉核心严重鞍形化。然而，这种畸变对配位基团的几何参数影响很小或没有影响：Fe-N(p) = 1.990(9) Å，Fe-N(NO) = 1.650(2) Å，Fe-N(L) = 1.983(2) Å，Fe-N-O = 177.0(3)°。对于配合物[Fe(OEP)(2-MeHIm)(NO)]ClO₄·0.5CH₂Cl₂（H₂OEP = 八乙基卟啉），不对称单元中有两个独立分子。标记为[Fe(OEP)(2-MeHIm)(NO)]⁺(pla)的阳离子具有接近平面的卟啉核心。对于该阳离子，Fe-N(p) = 2.014(8) Å，Fe-N(NO) = 1.649(2) Å，Fe-N(L) = 2.053(2) Å，Fe-N-O = 175.6(2)°。第二个阳离子[Fe(OEP)(2-MeHIm)(NO)]⁺(ruf)具有褶皱核心：Fe-N(p) = 2.003(7) Å，Fe-N(NO) = 1.648(2) Å，Fe-N(L) = 2.032(2) Å，Fe-N-O = 177.4(2)°。因此，两种类型的非平面核心变形均未对配位基团几何形状产生影响；蛋白质引起的核心变形也不太可能导致FeNO弯曲。[Fe(OEP)(2-MeHIm)(NO)]ClO₄的固态亚硝酰基伸缩频率为1917 cm⁻¹，[Fe(OETPP)(1-MeIm)(NO)]ClO₄的为1871 cm⁻¹，均处于线性Fe-N-O基团的频率范围内。[Fe(OEP)(2-MeHIm)(NO)]ClO₄的穆斯堡尔数据证实基态为抗磁性。此外，在4.2 K时的四极分裂值为1.88 mm/s，同质异能位移为(0.05 mm/s)，与其他具有线性Fe-N-O基团的（亚硝酰基）铁（III）卟啉配合物相似。晶体数据：[Fe(OETPP)(1-MeIm)(NO)]ClO₄·C₆H₅Cl，单斜晶系，空间群P2(1)/c，Z = 4，a = 12.9829(6) Å，b = 36.305(2) Å，c = 14.0126(6) Å，β = 108.087(1)°；[Fe(OEP)(2-MeHIm)(NO)]ClO₄·0.5CH₂Cl₂，三斜晶系，空间群P1，Z = 4，a = 14.062(2) Å，b = 16.175(3) Å，c = 19.948(3) Å，α = 69.427(3)°，β = 71.504(3)°，γ = 89.054(3)°。