Eskelinen Toni, Buss Stefan, Petrovskii Stanislav K, Grachova Elena V, Krause Maren, Kletsch Lukas, Klein Axel, Strassert Cristian A, Koshevoy Igor O, Hirva Pipsa
Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80100 Joensuu, Finland.
CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 11, D-48149 Münster, Germany.
Inorg Chem. 2021 Jun 21;60(12):8777-8789. doi: 10.1021/acs.inorgchem.1c00680. Epub 2021 Jun 7.
Cyclometalated complexes [M(Phbpy)(CN)] (HPhbpy = 6-phenyl-2,2'-bipyridine) of the group 10 metals (Ni, Pd, and Pt) bearing a carbanionic CNN pincer ligand were synthesized and studied in a combined experimental and computational DFT approach. All three complexes were crystallographically characterized showing closely packed dimers with head-to-tail stacking and short metal-metal contacts in the solid state. The computational models for geometries, excited states, and electronic transitions addressed both monomeric (, , and ) and dimeric (, , and ) entities. Photophysical properties and excited state dynamics of all title complexes were investigated in solution and in the solid at 298 and 77 K. [Ni(Phbpy)(CN)] and [Pd(Phbpy)(CN)] are virtually nonemissive in solution at 298 K, whereas [Pt(Phbpy)(CN)] shows phosphorescence in CHCl (DCM) solution (λ = 562 nm) stemming from a mixed MLCT/ILCT (metal-to-ligand charge transfer/intraligand charge transfer) state. At 77 K in a glassy frozen DCM:MeOH matrix, [Pd(Phbpy)(CN)] shows a remarkable emission (λ = 571 nm) with a photoluminescence quantum yield reaching almost unity, whereas [Ni(Phbpy)(CN)] is again nonemissive. Calculations on the monomeric models show that low-lying metal-centered states (MC, i.e., d-d* configuration) with dissociative character quench the photoluminescence. In the solid state, the complexes [M(Phbpy)(CN)] show defined photoluminescence bands (λ = 561 nm for Pd and 701 nm for Pt). Calculations on the dimeric models shows that the axial M···M interactions alter the photophysical properties of and toward MMLCT (metal-metal-to-ligand charge transfer) excited states with showing temperature-dependent emission lifetimes, suggesting thermally activated delayed fluorescence, whereas displayed phosphorescence with excimeric character. The metal-metal interactions were analyzed in detail with the quantum theory of atoms in molecules approach.
合成了第10族金属（镍、钯和铂）带有碳负离子型CNN钳形配体的环金属化配合物[M(Phbpy)(CN)]（HPhbpy = 6-苯基-2,2'-联吡啶），并采用实验和计算DFT相结合的方法对其进行了研究。所有三种配合物均通过晶体学表征，显示出在固态中具有头对头堆积和短金属-金属接触的紧密堆积二聚体。针对几何结构、激发态和电子跃迁的计算模型涉及单体（、和）和二聚体（、和）实体。在298 K和77 K下，研究了所有标题配合物在溶液和固体中的光物理性质和激发态动力学。[Ni(Phbpy)(CN)]和[Pd(Phbpy)(CN)]在298 K的溶液中几乎不发光，而[Pt(Phbpy)(CN)]在CHCl（二氯甲烷）溶液（λ = 562 nm）中显示出源于混合MLCT/ILCT（金属-配体电荷转移/配体内电荷转移）态的磷光。在77 K的玻璃态冷冻二氯甲烷：甲醇基质中，[Pd(Phbpy)(CN)]显示出显著的发射（λ = 571 nm），光致发光量子产率几乎达到1，而[Ni(Phbpy)(CN)]再次不发光。对单体模型的计算表明，具有解离特征的低能金属中心态（MC，即d-d*构型）会淬灭光致发光。在固态中，配合物[M(Phbpy)(CN)]显示出明确的光致发光带（钯的λ = 561 nm，铂的λ = 701 nm）。对二聚体模型的计算表明，轴向M···M相互作用将和的光物理性质改变为朝向MMLCT（金属-金属-配体电荷转移）激发态，显示出温度依赖性的发射寿命，表明存在热激活延迟荧光，则显示出具有准分子特征的磷光。采用分子中原子的量子理论方法对金属-金属相互作用进行了详细分析。
