Two diazapyrenes, 5,10-dimethyl-4,9-diazapyrene (1) and novel 2,7-dimethyl-4,9-diazapyrene (2) have been synthesized. Their crystal structures are reported here and are the first representatives of diazapyrenes. Crystal data: (1) monoclinic, P21/c, a = 4.0246 (5), b = 15.5147 (5), c = 9.1453 (9) Å, β = 101.23 (1)°, V = 560.1 (1) Å3, Z = 2, R = 0.043; (2) monoclinic, C2/m, a = 12.4968 (3), b = 11.4751 (4), c = 3.9615 (5) Å, β = 96.80 (1)°, V = 564.09 (5) Å3, Z = 2, R = 0.0405. The experimental bond lengths are compared with those calculated by molecular mechanics (MM3), semi-empirical methods (MOPAC6.0-PM3, AM1, MNDO) and values predicted by valence-bond and variable-electronegativity self-consistent field (VESCF) methods. π\cdotsπ interactions in (1), (2) and seventeen other pyrene and pyrene-like molecules selected from the Cambridge Structural Database [Allen & Kennard (1993). Chem. Des. Autom. News, 8, 131–137] have been studied. The following quantitative parameters of π\cdotsπ interactions have been calculated: the shortest crystallographic axis, the offset parameter, the interplanar angle, the interactive volume and the overlapping surfaces. They are used for the classification of crystal-packing motifs; a high predominance of β and a few cases of γ and sandwich-herringbone types are observed. In addition, electronegativity, the sum of partial atomic charges of the ring non-H atoms and the number of aromatic skeleton electrons are used as parameters for classification. MOPAC-PM3 was used to calculate the partial atomic charges in (1), (2) and pyrene analogues. Correlations between geometrical and electronic structure parameters reveal an analogy between the β-type structures and the crystal structure of graphite.
我们合成了两种二氮杂环戊烯,即 5,10-二甲基-4,9-二氮杂环戊烯(1)和新型 2,7-二甲基-4,9-二氮杂环戊烯(2)。本文报告了它们的晶体结构,它们是二氮杂并芘的首批代表。晶体数据:(1) 单斜,P21/c,a = 4.0246 (5),b = 15.5147 (5),c = 9.1453 (9) Å,β = 101.23 (1)°,V = 560.1 (1) Å3,Z = 2,R = 0.043;(2)单斜,C2/m,a = 12.4968 (3),b = 11.4751 (4),c = 3.9615 (5)埃,β = 96.80 (1)°,V = 564.09 (5) Å3,Z = 2,R = 0.0405。实验键长与分子力学 (MM3)、半经验方法 (MOPAC6.0-PM3、AM1、MNDO) 计算的键长以及价键和变电负性自洽场 (VESCF) 方法预测的键长进行了比较。从剑桥结构数据库 [Allen & Kennard (1993). Chem. Des. Autom. News, 8, 131-137] 中选取了 (1)、(2) 和其他十七种芘和类芘分子中的πcdotsπ 相互作用进行了研究。计算出了π/cdotsπ相互作用的以下定量参数:最短晶轴、偏移参数、平面间角度、相互作用体积和重叠面。它们被用于晶体堆积图案的分类;观察到的晶体堆积图案主要是 β 型,少数是 γ 型和三明治-人字形型。此外,电负性、环上非 H 原子的部分原子电荷之和以及芳香骨架电子数也被用作分类参数。MOPAC-PM3 用于计算 (1)、(2) 和芘类似物的部分原子电荷。几何和电子结构参数之间的相关性揭示了 β 型结构与石墨晶体结构之间的相似性。