A wide range of functionalized pyridine ligands have been employed to synthesize a variety of Pd(II) complexes of the general formulas [PdL₄](NO₃)₂ and [PdL₂Y₂], where L = 4-X-py and Y = Cl^– or NO₃^–. Their structures have been unambiguously established via analytical and spectroscopic methods in solution (NMR spectroscopy and mass spectrometry) as well as in the solid state (X-ray diffraction). This in-depth characterization has shown that the functionalization of ligand molecules with groups of either electron-withdrawing or -donating nature (EWG and EDG) results in significant changes in the physicochemical properties of the desired coordination compounds. Downfield shifts of signals in the ¹H NMR spectra were observed upon coordination within and across the complex families, clearly indicating the relationship between NMR chemical shifts and the ligand basicity as estimated from pK_a values. A detailed crystallographic study has revealed the operation of a variety of weak interactions, which may be factors explaining aspects of the solution chemistry of the complexes. The Pd(II) complexes have been found to be efficient and versatile precatalysts in Suzuki–Miyaura and Heck cross-coupling reactions within a scope of structurally distinct substrates, and factors have been identified that have contributed to efficiency improvement in both processes.

中文翻译：

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Pd(II) 与吡啶配体的配合物：取代基对 NMR 数据、晶体结构和催化活性的影响

广泛的功能化吡啶配体已被用于合成各种通式 [Pd L ₄ ](NO ₃ ) ₂和 [Pd L ₂ Y ₂ ] 的 Pd(II) 配合物，其中L = 4-X- py 和 Y = Cl ^–或 NO ₃ ^–. 它们的结构已通过溶液中的分析和光谱方法（核磁共振光谱和质谱）以及固态（X 射线衍射）明确确定。这种深入的表征表明，具有吸电子或供电子性质的基团（EWG 和 EDG）的配体分子的官能化导致所需配位化合物的物理化学性质发生显着变化。¹ H NMR 光谱中信号的低场位移在复合族内部和之间的配位时观察到，清楚地表明 NMR 化学位移和配体碱度之间的关系，由 p K _a估计价值观。详细的晶体学研究揭示了各种弱相互作用的作用，这可能是解释配合物溶液化学方面的因素。已发现 Pd(II) 配合物在结构不同的底物范围内是 Suzuki-Miyaura 和 Heck 交叉偶联反应中有效且通用的预催化剂，并且已确定有助于提高这两个过程效率的因素。