The NCN palladium(II) pincer complex [^Benzoyl(N∧C∧N)PdBr] (16) was synthesized by the oxidative addition of ^Benzoyl(N∧C∧N)Br to Pd(dba)₂ in 85% yield [(N∧C∧N) = 5-tert-butyl-1,3-bis(N-substituted benzimidazol-2′-yl)phenyl)]. Then treatment of complex 16 with KI yielded the iodopalladium complex [^Benzoyl(N∧C∧N)PdI] (17) in 92% yield. Furthermore, a series of cationic palladium(II) complexes, including [^Benzoyl(N∧C∧N)Pd(MeCN)]⁺[BF₄]⁻ (18), [^Benzoyl(N∧C∧N)Pd(MeCN)]⁺[SbF₆]⁻ (19), and [^Benzoyl(N∧C∧N)Pd(OTf)] (20), were prepared in 68–79% yields by the reaction of the neutral palladium(II) complex (16) with AgBF₄, AgSbF₆, and AgOTf, respectively. Similarly, previously synthesized ^Tosyl(N∧C∧N)PdBr [5-tert-butyl-1,3-bis(N-tosylbenzimidazol-2′-yl)phenyl]palladium bromide (5b) was treated with AgSO₃CF₃ and AgSbF₆ to afford cationic palladium(II) complexes [^Tosyl(N∧C∧N)Pd(OTf)] (21) and [^Tosyl(N∧C∧N)Pd(MeCN)]⁺[SbF₆]⁻ (22) in 41 and 61% yields, respectively. 5-tert-Butyl-1,3-bis[{(N-tosylbenzimidazol-2′-yl)phenyl}palladium(II)] triflate (21) exhibited an unsupported metallophillic Pd···Pd interaction [3.166(8) Å] that is corroborated by X-ray crystallographic studies. Compared to other cationic palladium complexes, complex 21 was found to be less stable. In Atoms in Molecule (AIM) analysis, the bond critical point (ρ) between Pd and Pd atoms is 0.000865 au, supporting the presence of metallophillic interaction in complex 21. The bond strength of the Pd···Pd bond was also measured by density functional theory calculations that indicated that the calculated bond order was approximately one-fourth of the normal covalent Pd–Pd bond (natural atomic orbital bond order method). All eight complexes, two neutral and six cationic, were characterized by common spectroscopic techniques, and six complexes were corroborated by X-ray diffraction studies.

中文翻译：

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5-叔丁基-1,3-双（N-取代的苯并咪唑-2'-基）苯的阳离子NCN钯（II）钳形配合物：合成，结构和Pd···Pd嗜金属相互作用

的NCN钯（II）钳形络合物[^苯甲酰（N∧C∧N）PDBR]（16）由氧化加成的合成^将苯甲酰（N∧C∧N）溴与Pd（DBA）₂产率85％[（ N ＝ C ＝ N）＝ 5-叔丁基-1，3-双（N-取代的苯并咪唑-2'-基）苯基）]。然后用KI处理配合物16，得到碘钯配合物[^苯甲酰基（N∧C∧N）PdI]（17），产率为92％。此外，一系列阳离子钯（II）配合物，包括[^苯甲酰基（N∧C∧N）Pd（MeCN）] ⁺ [BF ₄ ] ^-（18），[^苯甲酰基（N∧C∧N）Pd（MeCN）] ⁺ [SbF ₆ ] ^-（19）和[^苯甲酰基（N∧C∧N）Pd（OTf）]（20）的制备产率为68–79％，中性钯（II）配合物（16）与AgBF ₄，AgSbF ₆和AgOTf的反应。同样，将先前合成的^{甲苯磺酰基}（N∧C∧N）PdBr [5-叔丁基-1,3-双（N-^甲苯磺酰基苯并咪唑-2'-基）苯基]溴化钯（5b）用AgSO ₃ CF _3处理，用AgSbF ₆制备阳离子钯（II）络合物[ ^Tosyl（N∧C∧N）Pd（OTf）]（21）和[^{甲苯磺酰基}（N∧C∧N）Pd（MeCN）] ⁺ [SbF ₆ ] ^-（22）的产率分别为41％和61％。三氟甲磺酸5-叔丁基-1,3-双[{（N-甲苯磺酰基苯并咪唑-2'-基）苯基}钯（II）]三氟甲磺酸酯（21）表现出不受支撑的亲金属Pd···Pd相互作用[3.166（8）Å X射线晶体学研究证实了这一点。与其他阳离子钯配合物相比，发现配合物21的稳定性较差。在分子中的原子（AIM）分析中，Pd和Pd原子之间的键临界点（ρ）为0.000865 au，这支持在配合物21中存在亲金属相互作用。通过密度泛函理论计算还测量了Pd···Pd键的键强度，表明计算出的键序约为正常共价Pd-Pd键（自然原子轨道键序法）的四分之一。所有八种络合物（两种中性和六种阳离子）均通过常规光谱技术进行了表征，并且六种络合物通过X射线衍射研究得到了证实。