Tsaturyan Arshak A, Budnyk Andriy P, Ramalingan Chennan
Institute of Physical and Organic Chemistry, Southern Federal University, Stachki Av. 194/2, 344090 Rostov-on-Don, Russian Federation.
Southern Scientific Center, Russian Academy of Sciences, 41 Chehova str, 344006 Rostov-on-Don, Russian Federation.
ACS Omega. 2019 Jun 24;4(6):10991-11003. doi: 10.1021/acsomega.9b00921. eCollection 2019 Jun 30.
Geometry parameters, total energy of the system in different spin states, harmonic vibrational frequencies, and absorption spectra were computed for a range of mononuclear quaterpyridine Ru(II), Fe(III/II), and Co(III/II) complexes with two axial ambidentate CNS ligands by using density functional theory (DFT) and time-dependent DFT calculations. Both structural and electronic properties were found to be correlating with the type of the binding atom in the CNS ligand (isomerization differs by 4-13 kcal·mol). The N-bonding of CNS ligands is energetically favored. It was also found that the low spin (LS) state is the ground state for both Ru(II) and Co(III) complexes regardless of the CNS arrangement. The other complexes are the high-spin (HS) ground-state ones with the only exception of the S-bonded CNS isomer of the Fe(III) complex. The dependencies of energy differences between the HS and LS states versus C demonstrated stabilization of the HS state with an increasing amount of the exact exchange admixture (C) for iron and cobalt complexes. An opposite behavior was observed for ruthenium complexes. The best match in harmonic vibrational frequencies between the experimental and calculated values has been reached at C = 0.15 for all the complexes. The absorption profile of the Fe(II) complex with the alternatively bonded CNS ligands strongly depends on the angle between them. The light-harvesting efficiency of the Fe(II) complexes is very similar (∼0.4) and sufficiently close to that of the Ru(II) complexes. The iron-based coordination compounds are considered as a prospective dye for dye-sensitized solar cells. The results of calculations were completed with experimental reference data, thus providing a systematic compendium for practical use.
通过使用密度泛函理论（DFT）和含时DFT计算，对一系列带有两个轴向两可配位体CNS配体的单核四吡啶钌（II）、铁（III/II）和钴（III/II）配合物，计算了几何参数、不同自旋态下体系的总能量、谐振动频率和吸收光谱。发现结构和电子性质都与CNS配体中结合原子的类型相关（异构化相差4 - 13千卡·摩尔）。CNS配体的N键合在能量上更有利。还发现，无论CNS的排列如何，低自旋（LS）态都是Ru（II）和Co（III）配合物的基态。其他配合物是高自旋（HS）基态配合物，唯一的例外是Fe（III）配合物的S键合CNS异构体。HS和LS态之间的能量差与C的依赖关系表明，对于铁和钴配合物，随着精确交换混合量（C）的增加，HS态趋于稳定。钌配合物则表现出相反的行为。对于所有配合物，在C = 0.15时，实验值与计算值之间的谐振动频率达到了最佳匹配。具有交替键合CNS配体的Fe（II）配合物的吸收谱强烈依赖于它们之间的夹角。Fe（II）配合物的光捕获效率非常相似（约为0.4），并且与Ru（II）配合物的光捕获效率足够接近。铁基配位化合物被认为是染料敏化太阳能电池的一种有前景的染料。计算结果与实验参考数据相结合，从而提供了一个可供实际使用的系统概要。
