Ossinger Sascha, Prescimone Alessandro, Häussinger Daniel, Wenger Oliver S
Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland.
Inorg Chem. 2022 Jul 11;61(27):10533-10547. doi: 10.1021/acs.inorgchem.2c01438. Epub 2022 Jun 29.
Recently reported manganese(I) complexes with chelating arylisocyanide ligands exhibit luminescent metal-to-ligand charge-transfer (MLCT) excited states, similar to ruthenium(II) polypyridine complexes with the same d valence electron configuration used for many different applications in photophysics and photochemistry. However, chelating arylisocyanide ligands require substantial synthetic effort, and therefore it seemed attractive to explore the possibility of using more readily accessible monodentate arylisocyanides instead. Here, we synthesized the new Mn(I) complex [Mn(CNdippPh)]PF with the known ligand CNdippPh = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide. This complex was investigated by NMR spectroscopy, single-crystal structure analysis, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) measurements, IR spectroscopy supported by density functional theory (DFT) calculations, cyclic voltammetry, and time-resolved as well as steady-state UV-vis absorption spectroscopy. The key finding is that the new Mn(I) complex is nonluminescent and instead undergoes arylisocyanide ligand loss during continuous visible laser irradiation into ligand-centered and charge-transfer absorption bands, presumably owed to the population of dissociative d-d excited states. Thus, it seems that chelating bi- or tridentate binding motifs are essential for obtaining emissive MLCT excited states in manganese(I) arylisocyanides. Our work contributes to understanding the basic properties of photoactive first-row transition metal complexes and could help advance the search for alternatives to precious metal-based luminophores, photocatalysts, and sensors.
最近报道的含有螯合芳基异腈配体的锰（I）配合物表现出发光的金属到配体电荷转移（MLCT）激发态，类似于具有相同d价电子构型的钌（II）多吡啶配合物，后者在光物理和光化学中有许多不同的应用。然而，螯合芳基异腈配体需要大量的合成工作，因此探索使用更容易获得的单齿芳基异腈的可能性似乎很有吸引力。在此，我们用已知的配体CNdippPh = 4-(3,5-二甲氧基苯基)-2,6-二异丙基苯基异腈合成了新的锰（I）配合物[Mn(CNdippPh)]PF。通过核磁共振光谱、单晶结构分析、高分辨率电喷雾电离质谱（HR-ESI-MS）测量、密度泛函理论（DFT）计算支持的红外光谱、循环伏安法以及时间分辨和稳态紫外可见吸收光谱对该配合物进行了研究。关键发现是，新的锰（I）配合物不发光，而是在连续可见激光照射到以配体为中心和电荷转移吸收带期间发生芳基异腈配体损失，这可能归因于解离性d-d激发态的填充。因此，似乎螯合双齿或三齿结合基序对于在锰（I）芳基异腈中获得发射性MLCT激发态至关重要。我们的工作有助于理解光活性第一排过渡金属配合物的基本性质，并可能有助于推进对基于贵金属的发光体、光催化剂和传感器的替代品的探索。
