Here we report P K‐edge X‐ray absorption spectroscopy (XAS), density functional theory (DFT), and time‐dependent density functional theory (TDDFT) studies of [R₂P(CH₂)_nPR₂]PdCl₂, where R = phenyl or cyclohexyl and n = 1–3. P K‐edge XAS data were collected on room temperature CH₂Cl₂ solutions of [Ph₂P(CH₂)_nPPh₂]PdCl₂, where n = 1 (dppm; 1), 2 (dppe; 2), or 3 (dppp; 3) to determine if solid‐state variations in covalent Pd–P bonding reported previously (Inorg. Chem. 2015, 54, 5646) were present in solution. A flow cell was used to overcome challenges associated with photon‐induced decomposition, which often occurs rapidly in solution during ligand K‐edge XAS data collection at room temperature. While the solid‐state data for 2 revealed a 10 % increase in P 1s→Pd‐P σ* transition intensity compared to 1 and 3, no statistical difference in Pd–P covalency was observed for 1–3 in solution. In contrast, solid‐state P K‐edge XAS data collected on [Cy₂P(CH₂)_nPCy₂]PdCl₂, where n = 1 (dcpm; 4), 2 (dcpe; 5), or 3 (dcpp; 6), matched the trend in P 1s→Pd–P σ* transition intensity for solids of 1–3 despite exchanging the phenyl substituents for cyclohexyl. DFT and TDDFT calculations conducted on 4–6 corroborated the experimental data. Collectively, the solid‐state XAS and DFT results suggest that changes in the diphosphine backbone have the same relative effect on Pd–P σ covalency regardless of the substituents attached to phosphorus.

中文翻译：

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含苯基和环己基取代基的PdCl ₂二膦配合物的溶液和固态配体K-Edge XAS研究

在这里，我们报告了[R ₂ P（CH ₂）_n PR ₂ ] PdCl _2的PK边缘X射线吸收光谱法（XAS），密度泛函理论（DFT）和随时间变化的密度泛函理论（TDDFT）研究，其中R =苯基或环己基，n = 1-3。在[Ph ₂ P（CH ₂）_n PPh ₂ ] PdCl _2的室温CH ₂ Cl ₂溶液中收集PK边缘XAS数据，其中n = 1（dppm; 1），2（dppe; 2）或3 （dppp; 3），以确定是否在共价的Pd-P键合的固态变化先前报道（Inorg。化学。2015，54，5646）存在于溶液中。流通池用于克服与光子诱导分解相关的挑战，光解通常在室温下在配体K边缘XAS数据收集期间在溶液中迅速发生。而对于固态数据2显示P中1S→PD-Pσ*跃迁强度相比增加10％的1和3中，观察到在存在Pd-P共价无显着差异为1 - 3在溶液中。相反，在[Cy ₂ P（CH ₂）_n PCy ₂ ] PdCl ₂，其中n = 1（dcpm; 4），2（dcpe; 5）或3（dcpp; 6），符合P 1s→Pd– Pσ *固体的跃迁强度趋势。1 - 3尽管交换苯基取代基为环己基。在4 – 6上进行的DFT和TDDFT计算证实了实验数据。总的来说，固态XAS和DFT结果表明，无论与磷连接的取代基如何，二膦骨架的变化对Pd-Pσ共价都有相同的相对影响。