Hydrogen bonds and dispersion forces serving as molecular locks for tailored Group 11 bis(amidine) complexes
Hydrogen bonds and dispersion forces serving as molecular locks for tailored Group 11 bis(amidine) complexes
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氢键和色散力作为定制第 11 族双（脒）配合物的分子锁
DOI：
10.1039/d2qi00443g
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发表时间：
2022
影响因子：
7
通讯作者：
Stollenz, Michael
中科院分区：
文献类型：
--
作者：
Arras, Janet;Ugarte Trejo, Omar;Bhuvanesh, Nattamai;McMillen, Colin D.;Stollenz, Michael
柔性多齿双(酰胺)配体LH2，LH2={CH2NH(TBU)CN-2-(6-MePy)}2，对各种金属碎片起分子锁作用，形成双核配合物[LH2(MCL)2]，M=Cu2(1)，Au(2)，配位聚合物[{(LH2)2(Py)2(AgCl3)3}(Py)3]n(3)，以及通过形式插入MR片段形成的二茂铁基双缩二茂铁络合物[LH2(AuMes)2](4)；R=Cl，Mes)转化为氢氢的N-H⋯N氢键，产率为43-95%。配合物1、2和4在固体状态下具有C2对称结构，具有两个相互连接的11元环，并被两个分子内N-H⋯R-M氢键锁定。对计算几何优化的结构1a、2a和4a的QTAIM分析分别揭示了13、11和22个额外的键临界点，所有这些临界点都与分子内的弱吸引相互作用有关，主要代表色散力，有助于C2对称立体异构体在固体状态下的构象稳定。变温~1H核磁共振谱结合密度泛函理论计算表明，溶液中两个C2对称基态结构(ΔG‡c=11.1-13.8kcal−1)之间发生了动态构象转换，同时形成了保持氢键的具有Ci对称性的中间体。
A flexible polydentate bis(amidine) ligand LH2, LH2 = {CH2NH(tBu)CN-2-(6-MePy)}2, operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes [LH2(MCl)2], M = Cu (1), Au (2), the coordination polymer [{(LH2)2(py)2(AgCl)3}(py)3]n (3), and the dimesityl-digold complex [LH2(AuMes)2] (4) by formal insertion of MR fragments (M = Cu, Ag, Au; R = Cl, Mes) into the N–H⋯N hydrogen bonds of LH2 in yields of 43–95%. Complexes 1, 2, and 4 adopt C2-symmetrical structures in the solid state featuring two interconnected 11-membered rings that are locked by two intramolecular N–H⋯R–M hydrogen bonds. QTAIM analyses of the computational geometry-optimized structures 1a, 2a, and 4a reveal 13, 11, and 22 additional bond critical points, respectively, all of which are related to weak intramolecular attractive interactions, predominantly representing dispersion forces, contributing to the conformational stabilization of the C2-symmetrical stereoisomers in the solid state. Variable-temperature 1H NMR spectroscopy in combination with DFT calculations indicate a dynamic conformational interconversion between two C2-symmetrical ground state structures in solution (ΔG‡c = 11.1–13.8 kcal mol−1), which is accompanied by the formation of an intermediate possessing Ci symmetry that retains the hydrogen bonds.