DFT/TDDFT study of lanthanide(III) mono- and bisporphyrin complexes.
DFT/TDDFT study of lanthanide(III) mono- and bisporphyrin complexes.
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DOI：
10.1021/jp0632236
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发表时间：
2006-11
期刊：
影响因子：
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通讯作者：
M. Liao;J. Watts;Ming-Ju Huang
中科院分区：
文献类型：
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作者：
M. Liao;J. Watts;Ming-Ju Huang
采用DFT/TDDFT方法研究了镧系（III）单卟啉和双卟啉配合物的电子结构、分子结构和电子能谱。这些配合物包括YbP（acac）、YbP(2)、[YbP(2)]（+）、YbHP(2)和[YbP(2)](-)（其中P =卟啉，acac =乙酰丙酮）。为了阐明YbP（acac）中Yb的面外位移的来源，我们计算了平面D（4h）和变形C(4nu) YbP的非连接模型系统。为了比较，计算还扩展到包括C和[Ce(IV)P(2)]（+）体系。即使没有轴向配体，镧系元素也位于卟啉平面的上方；YbP分子结构从平面D（4h）变为非平面C（4nu）对称，导致能量显著降低。轴向配体使金属的面外位移更大，也改变了镧系单卟啉的氧化还原性质。考虑了几种可能的低洼状态，确定了YbP(2)和YbHP(2)的基态构型。YbP(2)被证实为单孔自由基。双卟啉配合物的特殊氧化还原性质可以很好地由计算的电离势和电子亲和来解释。TDDFT结果提供了各种镧系卟啉的紫外-可见和近红外吸收光谱的清晰描述。
The electronic structure, molecular structure, and electronic spectra of lanthanide(III) mono- and bisporphyrin complexes are investigated using a DFT/TDDFT method. These complexes include YbP(acac), YbP(2), [YbP(2)](+), YbHP(2), and [YbP(2)](-) (where P = porphine and acac = acetylacetonate). To shed some light on the origin of the out-of-plane displacement of Yb in YbP(acac), unligated model systems, namely, planar D(4h) and distorted C(4nu) YbP, were calculated. For comparison, the calculations were also extended to include the C and [Ce(IV)P(2) ](+) systems. Even without an axial ligand, the lanthanide atom lies considerably above the porphyrin plane; the distortion of the YbP molecular structure from a planar D(4h) to the nonplanar C(4nu) symmetry leads to a considerable energy lowering. The axial ligand makes the metal out-of-plane displacement even larger, and it also changes the redox properties of the lanthanide monoporphyrin. The ground-state configurations of YbP(2) and YbHP(2) were determined by considering several possible low-lying states. YbP(2) is confirmed to be a single-hole radical. The special redox properties of the bisporphyrin complexes can well be accounted for by the calculated ionization potentials and electron affinities. The TDDFT results provide a clear description of the UV-vis and near-IR absorption spectra of the various lanthanide porphyrins.