Sulfur K-edge X-ray absorption spectroscopy as a probe of ligand-metal bond covalency: Metal vs ligand oxidation in copper and nickel dithiolene complexes
Sulfur K-edge X-ray absorption spectroscopy as a probe of ligand-metal bond covalency: Metal vs ligand oxidation in copper and nickel dithiolene complexes
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DOI：
10.1021/ja0665949
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发表时间：
2007-02-28
影响因子：
15
通讯作者：
Solomon, Edward I.
中科院分区：
文献类型：
--
作者：
Sarangi, Ritimukta;George, Serena DeBeer;Solomon, Edward I.
结合Cu L边和S K边的X射线吸收数据和密度泛函理论（DFT）计算与S-33电子顺磁共振超精细结果关联，得到了（TBA）（2）[Cu（MNT）（2）]（TBA）四正丁基铵）中二硫杂环戊烯配体马来腈二硫纶（MNT）的S1 s-> 3 p跃迁的偶极积分（I-s）.将所得结果与来自XPS研究的硫化物的I-s相结合，以实验方式获得S 1 s-> 4p跃迁能（其反映S原子上的电荷，Q mol S）与Q mol S的大范围内的偶极积分之间的关系。结果表明，对于S上的高电荷，I-s可以与先前报道的I-s值不同，该I-s值是使用Q mol S的有限范围内的数据计算的。结合S K边、Cu K边和L边的X射线吸收数据和密度泛函理论计算，研究了[Cu（MNT）2]（2）-和[Ni（MNT）2]（2）-的单电子氧化反应. [Cu（MNT）（2）]（2）-向[Cu（MNT）（2）]-的转化导致分子中Cu原子上的电荷（Q mol Cu）的大变化，并且与基于金属的氧化一致。这伴随着来自配体的大量电荷捐赠，以分别基于增加的S K边缘和降低的Cu L边缘强度来补偿[Cu（MNT）2]中Cu上的高电荷。相比之下，[Ni（MNT）2] 2-氧化为[Ni（MNT）2]-导致Q mol Ni的微小变化，表明基于配体的氧化与具有主要配体特征的分子轨道psi*（SOMO）（单占据分子轨道）的氧化一致。
A combination of Cu L-edge and S K-edge X-ray absorption data and density functional theory (DFT) calculations has been correlated with S-33 electron paramagnetic resonance superhyperfine results to obtain the dipole integral (I-s) for the S 1s -> 3p transition for the dithiolene ligand maleonitriledithiolate (MNT) in (TBA)(2)[Cu(MNT)(2)] (TBA) tetra-n-butylammonium). The results have been combined with the I-s of sulfide derived from XPS studies to experimentally obtain a relation between the S 1s -> 4p transition energy (which reflects the charge on the S atom, Q mol S) and the dipole integral over a large range of Q mol S. The results show that, for high charges on S, I-s can vary from the previously reported I-s values, calculated using data over a limited range of Q mol S. A combination of S K-edge and Cu K-and L-edge X-ray absorption data and DFT calculations has been used to investigate the one-electron oxidation of [Cu(MNT)2](2)-and [Ni(MNT)(2)](2-). The conversion of [Cu(MNT)(2)](2)-to [Cu(MNT)(2)]-results in a large change in the charge on the Cu atom in the molecule (Q mol Cu) and is consistent with a metal-based oxidation. This is accompanied by extensive charge donation from the ligands to compensate the high charge on the Cu in [Cu(MNT) 2]based on the increased S K-edge and decreased Cu L-edge intensity, respectively. In contrast, the oxidation of [Ni(MNT) 2] 2-to [Ni(MNT) 2]-results in a small change in Q mol Ni, indicating a ligand-based oxidation consistent with oxidation of a molecular orbital, psi*(SOMO) (singly occupied molecular orbital), with predominant ligand character.