A series of Ni(II), Pd(II) and Pt(II) complexes [ML][PF₆]₂ [L = L¹, M = Ni (1), Pd (2), Pt (3); L = L², M = Ni (4), Pd (5), Pt (6)] and [Pt(L²)(acac)] (7) have been prepared by the reactions of two tetradentate macrocyclic amine-NHC ligand precursors, [H₂L¹][PF₆]₂ and [H₂L²][PF₆]₂, with Ni(OAc)₂·4H₂O, Pd(OAc)₂ and Pt(acac)₂ in the presence of NaOAc. Complex 7 is isolated along with 6 from the same reaction between [H₂L²][PF₆]₂ and Pt(acac)₂. There are two atropisomers in 1–3 and two achiral conformers in 4–6. The crystal structures of 1–3 and one conformer of 4–6 (4a–6a) have been determined by single-crystal X-ray diffraction studies. The metal ion is found to reside in the cavity of the macrocyclic ring and adopts a square-planar configuration. Detailed NMR studies including variable-temperature NMR spectroscopy reveal a dynamic interconverting process between two atropisomers of 1–3 in the solutions via a ring twisting mechanism. Two conformers in the equilibrated solution of 4–6, probably arising from the orientation of two amine N–H bonds with respect to the coordination plane, exchange slowly. Time-dependent ¹H NMR spectra show that one conformer (4a–6a) in solution converts into the other (4b–6b) via the inversion of the nitrogen atom.

中文翻译：

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具有大环胺N-杂环卡宾配体的10族金属配合物的合成，结构表征和NMR研究†

一系列Ni（II），Pd（II）和Pt（II）配合物[ML] [PF ₆ ] ₂ [L = L ¹，M = Ni（1），Pd（2），Pt（3）；通过两个四齿大环胺-NHC配体的反应制备了L = L ²，M = Ni（4），Pd（5），Pt（6）]和[Pt（L ²）（acac）]（7）。前体[H ₂ L ¹ ] [PF ₆ ] ₂和[H ₂ L ² ] [PF ₆] ₂，在NaOAc存在下用Ni（OAc）₂ ·4H ₂ O，Pd（OAc）₂和Pt（acac）₂。从[H ₂ L ² ] [PF ₆ ] ₂和Pt（acac）₂之间的相同反应中分离出配合物7和6。在1-3中有两个阻转异构体，在4-6中有两个非手性构象异构体。1-3的晶体结构和4-6（4a-6a的一个构象））是通过单晶X射线衍射研究确定的。发现金属离子驻留在大环的腔中并且采用正方形平面构型。包括变温NMR光谱在内的详细NMR研究表明，溶液中的两个1–3阻转异构体之间通过环加捻机制进行了动态相互转化过程。平衡溶液4–6中的两个构象异构体交换缓慢，可能是由于两个胺N–H键相对于配位平面的取向而引起的。时间依赖性¹ 1 H NMR光谱显示一个构象异构体（图4a-6A）的溶液转换成另一种（4B-6B）经由 氮原子的转化。