The Rotational Orientation Angles of Axial Ligands in Low-Spin Fe(III) Heme Complexes As Determined from Frozen-Solution Samples

从冷冻溶液样品中测定低自旋 Fe(III) 血红素复合物中轴向配体的旋转取向角

• 批准号: 63571026
• 负责人: SATO Mitsuo
• 金额: $ 1.34万
• 依托单位: Teikyo University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63571026/
• 关键词: Low-spin Fe(III) heme complex; Rotational orientation of rhombic field; Rotational orientation of axial ligand; Iron-57 hf splitting; Relative orientations of g and hf tensors; Pー450モデル錯体; P-450モデル錯体; 軸配位子の回転配向

Hyperfine (hf) splittings due to the ^<57>Fe nucleus (I=1/2) have been observed in frozen-solution ESR measurements on a series of low-spin Fe(III) heme complexes, Fe(TPP)L_1L_2, where TPP =tetraphenylporphine dianion, L_1 = RS^-, L_2 = MeOH, DMF, and RSH, and R = Et, n-Pr, i-Pr, n-Bu, s-Bu, and t-Bu. The hf splitting (A_<(i)>) values of the g_i absorption peaks (i = X, Y, Z) are analyzed within the framework of a low-symmetry (C_2) crystal field model to determine the rotational orientation angle (phi) of the axes of rhombic component field and that (phi_l) of the axial thiolato ligand plane (Fe-S-C plane) with the approximation of phi_l = phi. It is found that phi_l varies from 6 to 37ﾟ depending upon the thiolato ligand (RS^-), the 6th axial ligand (L_2), and the solvent system (CH_2Cl_2 - MeOH, DMF-MeOH, or CH_2Cl_2-RSH), but with no clear correlation between phi_l and RS^-. However, phi_l correlates well with the energy splittings in the three t_2 orbitals: phi_l increases as the tetragonal splitting decreases or as the rhombic splitting and crystal field rhombicly increase. These results suggest that two major factors, namely, steric and electronic effects, influence the axial ligand orientation. The observed angles phi_l = 6-37ﾟ are the results of the two effects.

在冷冻溶液ESR测量中，观察到了一系列低自旋Fe(III)血红素络合物Fe(TPP)L_1L_2的超精细(HF)分裂，其中TPP=四苯基卟啉双阴离子，L_1=RS^-，L_2=甲醇，DMF和RSH，R=Et，n-Pr，i-Pr，n-Bu，S-Bu和t-Bu。在低对称性(C2)晶场模型的框架下，分析了gI吸收峰(i=X，Y，Z)的HF分裂(A&lt；(I)&gt；)值，以Phi_L=Phi近似确定了菱形分量场轴的旋转取向角(Phi)和轴向硫醇配体平面(Fe-S-C面)的旋转取向角(Phi_L)。结果表明，pH_L随硫醇配体(RS^-)、第6轴配体(L_2)和溶剂体系(CH_2Cl_2-甲醇、DMF-甲醇或CH_2Cl_2-RSH)的不同而变化，但Phi_L与RS^-之间没有明显的相关性。然而，Phi_L与三个t2轨道上的能量分裂有很好的相关性：Phi_L随着四方分裂的减小或菱形分裂和晶场的菱形增大而增大。这些结果表明，立体效应和电子效应是影响配体轴向取向的两个主要因素。观测到的角Phi_L=6-37ﾟ是两种效应共同作用的结果。

项目成果

T.Itoh: "Deoxygenation of Oxiran Compounds to Olefins by[Fe_4S_4(SC_6H_5)_4]^<2-> in the Presence of NaBH_4" Tetrahedron Let.,. 30. 6387-6388 (1989)

T.Itoh：“在 NaBH_4 存在下，[Fe_4S_4(SC_6H_5)_4]^<2-> 将环氧乙烷化合物脱氧为烯烃”Tetrahedron Let.,。

A.Tohara: "Photoreduction of Hydroxotetramesitylporphinatoiron(III)in Aromatic Hydrocarbons and the Concurrent Generation of Hydroxyl Radical" Chem.Let.,. 153-156 (1989)

A.Tohara：“芳香烃中羟基四均基卟啉铁 (III) 的光还原以及同时生成羟基自由基”Chem.Let.,。

M. Sato, T. Otsuka, T. Ohya: "Electron Spin Resonance Studies of Low-Spin Ferric Heme Complexes in Frozen Solutions. Iron-57 Hyperfine Splittings and the Angular Orientation of Rhombic Crystal Field" Nippon Kagaku Kaishi, 522, 1988.

M. Sato、T. Otsuka、T. Ohya：“冷冻溶液中低自旋三价铁血红素复合物的电子自旋共振研究。Iron-57 超精细分裂和菱形晶体场的角取向”Nippon Kagaku Kaishi，522，1988。

A. Tohara, M. Sato: "Photoreduction of Hydroxotetramesitylporphinato)iron(III) in Aromatic Hydrocarbons and the Concurrent Generation of Hydroxyl Radical" Chemistry Letters, 153, 1989.

A. Tohara, M. Sato：“芳香烃中羟基四均基卟啉）铁 (III) 的光还原和同时生成羟基自由基”，《化学快报》，153，1989。

M.Sato: "Rotational Angular Orientation of Axial Thiolato Ligand in Low-Spin P-450 Model Complexes" J.Pharmacobio-Dyn.,. 13. s-5 (1990)

M.Sato：“低自旋 P-450 模型复合物中轴向硫醇配体的旋转角方向”J.Pharmacobio-Dyn.,。