A cobalt-nitrosyl complex with a hindered hydrotris(pyrazolyl) borate coligand: detailed electronic structure, and reactivity towards dioxygen
A cobalt-nitrosyl complex with a hindered hydrotris(pyrazolyl) borate coligand: detailed electronic structure, and reactivity towards dioxygen
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DOI：
10.1039/c7dt01565h
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发表时间：
2017-10-21
影响因子：
4
通讯作者：
Lehnert, Nicolai
中科院分区：
文献类型：
--
作者：
Fujisawa, Kiyoshi;Soma, Shoko;Lehnert, Nicolai
钴-亚硝酰基配合物[Co（NO）（L3）]由高度受阻的三齿氮配体氢化三（3-叔丁基-5-异丙基-1-吡唑基）硼酸盐（记为L3（-））支撑，并显示线性Co-N-O单元。该配合物是通过L3（-）的钾盐与钴-亚硝酰基前体[Co（NO）（2）（tmeda）]（BPh 4）（tmeda = N，N，N，'N'-四甲基乙二胺）反应制备的。所得钴-亚硝酰基配合物以及与分子氧反应的相应产物[Co（eta（2）-O2 N）（L3）]和[Co（eta（2）-O2 NO）（L3）]通过X射线晶体学和许多光谱方法（包括IR/远红外、UV-Vis和NMR光谱）表征。我们还进行了MCD测量和DFT计算，以进一步阐明[Co（NO）（L3）]的电子结构和配合物的光学性质。MCD光谱揭示了两个NO-到-Co的电荷转移跃迁，其具有强的激发态位移，引起MCD光谱中的振动进展，指示非常共价的Co-NO键。这些结果为Co-NO键的性质和配合物中的电子分布提供了新的见解，最好描述为[Co-II（NO-）（L3）]。
The cobalt-nitrosyl complex [Co(NO)(L3)] is supported by a highly hindered tridentate nitrogen ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl) borate (denoted as L3(-)), and shows a linear Co-N-O unit. This complex was prepared by the reaction of the potassium salt of L3(-) with the cobalt-nitrosyl precursor [Co(NO)(2)(tmeda)](BPh4) (tmeda = N, N, N,' N'-tetramethylethylenediamine). The obtained cobalt-nitrosyl complex as well as the corresponding products from the reaction with dioxygen, [Co(eta(2)-O2N) (L3)] and [Co(eta(2)-O2NO)(L3)], were characterised by X-ray crystallography and a number of spectroscopic methods including IR/far-IR, UV-Vis, and NMR spectroscopy. We also performed MCD measurements and DFT calculations to further elucidate the electronic structure of [Co(NO)(L3)] and the optical properties of the complex. The MCD spectra reveal two NO-to-Co charge-transfer transitions with strong excited state displacements that give rise to vibrational progressions in the MCD spectra, indicative of a very covalent Co-NO bond. These results provide new insight into the properties of the Co-NO bond and the electron distribution in the complex, which is best described as [Co-II(NO-)(L3)].