Abstract：
N-X⋅⋅⋅- O-N+ halogen-bonded systems formed by 27 pyridine N-oxides (PyNOs) as halogen-bond (XB) acceptors and two N-halosuccinimides, two N-halophthalimides, and two N-halosaccharins as XB donors are studied in silico, in solution, and in the solid state. This large set of data (132 DFT optimized structures, 75 crystal structures, and 168 1 H NMR titrations) provides a unique view to structural and bonding properties. In the computational part, a simple electrostatic model (SiElMo) for predicting XB energies using only the properties of halogen donors and oxygen acceptors is developed. The SiElMo energies are in perfect accord with energies calculated from XB complexes optimized with two high-level DFT approaches. Data from in silico bond energies and single-crystal X-ray structures correlate; however, data from solution do not. The polydentate bonding characteristic of the PyNOs\' oxygen atom in solution, as revealed by solid-state structures, is attributed to the lack of correlation between DFT/solid-state and solution data. XB strength is only slightly affected by the PyNO oxygen properties [(atomic charge (Q), ionization energy (Is,min ) and local negative minima (Vs,min )], as the σ-hole (Vs,max ) of the donor halogen is the key determinant leading to the sequence N-halosaccharin>N-halosuccinimide>N-halophthalimide on the XB strength.
摘要：
由27个吡啶N-氧化物（PyNOs）作为卤键（XB）受体和两个N-卤代琥珀酰亚胺形成的N-X···-O-N卤素键合系统，两种N-卤代苯二甲酰亚胺，并对两种N-卤糖素作为XB供体进行了计算机模拟研究，在解决方案中，在固态。这一大组数据(132个DFT优化结构，75个晶体结构，和1681HNMR滴定）提供了结构和粘合性能的独特观点。在计算部分，建立了仅使用卤素供体和氧受体的性质来预测XB能量的简单静电模型（SiElMo）。SiElMo能量与通过两种高级DFT方法优化的XB复合物计算的能量完全吻合。来自硅键能和单晶X射线结构的数据相关，然而，来自解决方案的数据没有。溶液中PyNOs\'氧气的多齿结合特性，正如固态结构所揭示的，归因于DFT/固态和溶液数据之间缺乏相关性。XB强度仅受到PyNO氧性质的轻微影响[(原子电荷(Q)，电离能(Is,最小值)和局部负最小值(Vs，min)],作为？-孔(Vs，供体卤素的max）是导致XB强度上的序列N-卤代丁二酰亚胺>N-卤代苯二甲酰亚胺的关键决定因素。
