Department of Chemistry, The George Washington University , 800 22nd Street NW, Washington, D.C. 20052, United States.
Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil.
J Am Chem Soc. 2017 Aug 9;139(31):10843-10855. doi: 10.1021/jacs.7b05689. Epub 2017 Jul 26.
Assembly of a family of 12 supramolecular compounds containing [AnOCl] (An = U, Np, Pu), via hydrogen and halogen bonds donated by substituted 4-X-pyridinium cations (X = H, Cl, Br, I), is reported. These materials were prepared from a room-temperature synthesis wherein crystallization of unhydrolyzed and valence-pure [An(VI)OCl] (An = U, Np, Pu) tectons is the norm. We present a hierarchy of assembly criteria based on crystallographic observations and subsequently quantify the strengths of the non-covalent interactions using Kohn-Sham density functional calculations. We provide, for the first time, a detailed description of the electrostatic potentials of the actinyl tetrahalide dianions and reconcile crystallographically observed structural motifs and non-covalent interaction acceptor-donor pairings. Our findings indicate that the average electrostatic potential across the halogen ligands (the acceptors) changes by only ∼2 kJ mol across the AnO series, indicating that the magnitude of the potential is independent of the metal center. The role of the cation is therefore critical in directing structural motifs and dictating the resulting hydrogen and halogen bond strengths, the former being stronger due to the positive charge centralized on the pyridyl nitrogen, N-H. Subsequent analyses using the quantum theory of atoms in molecules and natural bond orbital approaches support this conclusion and highlight the structure-directing role of the cations. Whereas one can infer that Columbic attraction is the driver for assembly, the contribution of the non-covalent interaction is to direct the molecular-level arrangement (or disposition) of the tectons.
报道了通过取代的 4-X-吡啶鎓阳离子（X = H、Cl、Br、I）提供的氢键和卤素键，组装包含 [AnOCl]（An = U、Np、Pu）的 12 个超分子化合物家族。这些材料是通过室温合成制备的，其中未水解和价态纯的 [An(VI)OCl]（An = U、Np、Pu）构筑块的结晶是常态。我们提出了基于晶体学观察的组装标准层次结构，并随后使用 Kohn-Sham 密度泛函计算量化非共价相互作用的强度。我们首次详细描述了锕系元素四卤化物二阴离子的静电势，并协调了晶体学观察到的结构基元和非共价相互作用受体-供体配对。我们的发现表明，在 AnO 系列中，卤素配体（受体）上的平均静电势仅变化约 2 kJ mol，表明电势的大小与金属中心无关。因此，阳离子的作用对于指导结构基元和决定所得氢键和卤素键强度至关重要，前者由于吡啶氮 N-H 上的正电荷而更强。使用分子中的原子量子理论和自然键轨道方法进行的后续分析支持这一结论，并强调了阳离子的结构导向作用。虽然可以推断库仑吸引力是组装的驱动力，但非共价相互作用的贡献是指导构筑块的分子水平排列（或布置）。
