Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36,D-45470 Mülheim an der Ruhr, Germany.
Chemistry. 2010 Mar 22;16(12):3628-45. doi: 10.1002/chem.200903381.
A detailed spectroscopic and quantum chemical analysis is presented to elucidate the electronic structures of the octahedral complexes Fe(Et(2)dtc)(3-n)(mnt)(n) (1-4, n=3, 2, 1, 0) and their one-electron oxidized analogues Fe(Et(2)dtc)(3-n)(mnt)(n) (1(ox)-4(ox)); (mnt)(2-) represents maleonitriledithiolate(2-) and (Et(2)dtc)(1-) is the diethyldithiocarbamato(1-) ligand. By using X-ray crystallography, Mössbauer spectroscopy, and Fe and S K-edge X-ray absorption spectroscopy (XAS) it is convincingly shown that, in contrast to our previous studies on Fe(cyclam)(mnt) (cyclam=1,4,8,11-tetraazacyclotetradecane), the oxidation of 1-4 is metal-centered yielding the genuine Fe(IV) complexes 1(ox)-4(ox). For the latter complexes, a spin ground state of S=1 has been established by magnetic susceptibility measurements, which indicates a low-spin d(4) configuration. DFT calculations at the B3LYP level support this electronic structure and exclude the presence of a ligand pi radical coordinated to an intermediate-spin ferric ion. Mössbauer parameters and XAS spectra have been calculated to calibrate our computational results against the experiment. Finally, a simple ligand-field approach is presented to correlate the structural features obtained from X-ray crystallography (100 K) with the spectroscopic data.
本文进行了详细的光谱和量子化学分析，以阐明八面体配合物Fe(Et(2)dtc)(3-n)(mnt)(n)（1-4，n=3，2，1，0）及其单电子氧化类似物Fe(Et(2)dtc)(3-n)(mnt)(n)（1(ox)-4(ox)）的电子结构；(mnt)(2-)代表丙二腈二硫代甲酸盐(2-)，(Et(2)dtc)(1-)是二乙二硫代氨基甲酸盐(1-)配体。通过使用 X 射线晶体学、穆斯堡尔光谱学和 Fe 和 S K 边 X 射线吸收光谱（XAS），令人信服地表明，与我们之前对Fe(cyclam)(mnt)（cyclam=1,4,8,11-四氮杂环十四烷）的研究相反，1-4 的氧化是金属中心的，生成真正的 Fe(IV)配合物 1(ox)-4(ox)。对于后一种配合物，通过磁化率测量确定了自旋基态为 S=1，这表明了低自旋 d(4)构型。B3LYP 水平的 DFT 计算支持这种电子结构，并排除了配体 pi 自由基与中间自旋铁离子配位的存在。计算了穆斯堡尔参数和 XAS 谱，以将我们的计算结果与实验结果进行校准。最后，提出了一种简单的配体场方法，将 X 射线晶体学（100 K）获得的结构特征与光谱数据相关联。
