Excitation-Wavelength-Dependent Photophysics of d 8 d 8 Di-isocyanide Complexes
Excitation-Wavelength-Dependent Photophysics of d 8 d 8 Di-isocyanide Complexes
复制标题
d 8 d 8 二异氰化物配合物的激发波长依赖性光物理学
DOI：
10.1021/acs.inorgchem.1c02645
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发表时间：
2022
影响因子：
4.6
通讯作者：
Vlček, Antonín
中科院分区：
文献类型：
--
作者：
Pižl, Martin;Hunter, Bryan M.;Sazanovich, Igor V.;Towrie, Michael;Gray, Harry B.;Záliš, Stanislav;Vlček, Antonín
双核Rh(I)和Ir(I) TMB（2,5-二甲基-2,5-二异氰环己烷）和二氨基（1,8-二异氰环烷）配合物具有dσ*pσ和dπpσ单重态和三重态，可在可见光和紫外光谱区选择性激发。利用微扰自旋轨道TDDFT，我们揭示了这些电子跃迁的详细特征和自旋混合，并发现pσ和dπ轨道在C≡N -基团上的离域使得C≡N拉伸振动敏感地记录了电子激发后的电子密度和结构变化。在可见光、375 nm和316 nm激发后测量的皮秒时间分辨红外光谱显示了与激发波长相关的失活级联。在可见光照射下制备了1dσ*pσ态，经过1 ~ 2个（亚）皮秒的弛豫步骤后，经过70 ~ 1300 ps的系统间穿越到3dσ*pσ，这对于更灵活的尺寸配合物来说是更快的。uv激发的3 - dπpσ态以（亚）皮秒动力学通过高三重态和混合自旋态的流形衰减到3 - dσ*pσ，寿命范围为6-19 ps （316 nm）和19-43 ps (375 nm，仅Ir)，绕过1 - dσ*pσ。大多数激发态转换和一些弛豫步骤都伴随着基态的直接衰减，这对于最灵活的长/重叠Rh（维）构象尤其明显。
Binuclear Rh(I) and Ir(I) TMB (2,5-dimethyl-2,5-diisocyanohexane) and dimen (1,8-diisocyanomenthane) complexes possess dσ*pσ and dπpσ singlet and triplet excited states that can be selectively excited in the visible and UV spectral regions. Using perturbational spin–orbit TDDFT, we unraveled the detailed character and spin mixing of these electronic transitions and found that delocalization of pσ and dπ orbitals over C≡N– groups makes C≡N stretching vibrations sensitive reporters of electron density and structural changes upon electronic excitation. Picosecond time-resolved infrared spectra measured after visible light, 375 nm, and 316 nm excitation revealed excitation-wavelength-dependent deactivation cascades. Visible light irradiation prepares the1dσ*pσ state that, after one or two (sub)picosecond relaxation steps, undergoes 70–1300 ps intersystem crossing to3dσ*pσ, which is faster for the more flexible dimen complexes. UV-excited1,3dπpσ states decay with (sub)picosecond kinetics through a manifold of high-lying triplet and mixed-spin states to3dσ*pσ with lifetimes in the range of 6–19 ps (316 nm) and 19–43 ps (375 nm, Ir only), bypassing1dσ*pσ. Most excited-state conversion and some relaxation steps are accompanied by direct decay to the ground state that is especially pronounced for the most flexible long/eclipsed Rh(dimen) conformer.