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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Synthesis, structure and dynamics of NHC-based palladium macrocycles
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Synthesis, structure and dynamics of NHC-based palladium macrocycles

机译：NHC基钯大环化合物的合成，结构和动力学

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A series of macrocyclic CNC pincer pro-ligands based on bis(imidazolium)lutidine salts with octa-, decaand dodecamethylene spacers have been prepared and their coordination chemistry investigated. Using a Ag_2O based transmetallation strategy, cationic palladium(II) chloride complexes [PdCl{CNC-(CH_2)_n}]- [BAr_4~F] (n = 8, 10, 12; Ar~F = 3,5-C_6H_3(CF_3)_2) were prepared and fully characterised in solution, by NMR spectroscopy and ESI-MS, and in the solid-state, by X-ray crystallography. The smaller macrocyclic complexes (n = 8 and 10) exhibit dynamic behaviour in solution, involving ring flipping of the alkyl spacer across the Pd-Cl bond, which was interrogated by variable temperature NMR spectroscopy. In the solidstate, distorted coordination geometries are observed with the spacer skewed to one side of the Pd-Cl bond. In contrast, a static C_2 symmetric structure is observed for the dodecamethylene based macrocycle. For comparison, palladium(II) fluoride analogues [PdF{CNC-(CH_2)_n}][BAr_4~F] (n = 8, 10, 12) were also prepared and their solution and solid-state structures contrasted with those of the chlorides. Notably, these complexes exhibit very low frequency ~(19)F chemical shifts (ca. -400 ppm) and the presence of C-H?F interactions (~(2h)JFC coupling observed by ~(13)C NMR spectroscopy). The dynamic behaviour of the fluoride complexes is largely consistent with the smaller ancillary ligand; [PdF{CNC-(CH_2)_8}][BAr_4~F] exceptionally shows C_(2v) time averaged symmetry in solution at room temperature (CD_2Cl_2, 500 MHz) as a consequence of dual fluxional processes of the pincer backbone and alkyl spacer.
机译：制备了一系列基于双（咪唑鎓）二甲基吡啶盐与八-，十-和十二-十二烷基间隔基的大环CNC夹钳原配体，并研究了它们的配位化学。使用基于Ag_2O的金属转移策略，阳离子氯化钯（II）络合物[PdCl {CNC-（CH_2）_n}]-[BAr_4〜F]（n = 8，10，12; Ar〜F = 3,5-C_6H_3（制备了CF_3）_2），并在溶液中通过NMR光谱和ESI-MS进行了全面表征，并在固态下通过X射线晶体学进行了全面表征。较小的大环络合物（n = 8和10）在溶液中表现出动态行为，涉及烷基间隔基通过Pd-Cl键的环翻转，这通过可变温度NMR光谱法进行了研究。在固态中，观察到扭曲的配位几何结构，其中间隔基偏向Pd-Cl键的一侧。相反，对于基于十二亚甲基的大环，观察到静态的C_2对称结构。为了进行比较，还制备了氟化钯（II）类似物[PdF {CNC-（CH_2）_n}] [BAr_4〜F]（n = 8、10、12），并将它们的溶液和固态结构与它们的对比。氯化物。值得注意的是，这些配合物表现出非常低的〜（19）F化学位移频率（约-400 ppm），并且存在C-H2F相互作用（〜（13h）NMR光谱观察到〜（2h）JFC偶联）。氟化物配合物的动力学行为与较小的辅助配体基本一致。 [PdF {CNC-（CH_2）_8}] [BAr_4〜F]表现出室温（CD_2Cl_2，500 MHz）在溶液中的C_（2v）时间平均对称性，这是钳形骨架和烷基间隔基的双重通量过程的结果。

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