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首页> 外文期刊>Acta Crystallographica Section E: Crystallographic Communications >Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis­(pent-4-ynoate)
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Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis­(pent-4-ynoate)

机译：4-甲基-2-氧代-2-H-色烯-7,8-二乙酸二甲酯和4-甲基-2-氧代-2H-色烯-7,8-二（双-4-戊酸酯）的晶体结构

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摘要

In the structures of the two title coumarin derivatives, C14H12O6, (1), and C20H16O6, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by π–π stacking involving the coumarin rings and weak C—H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R22(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π–π stacking.
机译：在两个标题香豆素衍生物C14H12O6（1）和C20H16O6，（2）的结构中，一个带有乙酸盐，另一个带有戊-4-酸取代基，两个香豆素环几乎都是平面的。在（1）中，两个乙酸酯取代基均显着旋转出香豆素平面，以使空间排斥最小化。一个乙酸酯取代基在两个等价构象上是无序的，占空度为0.755（17）和0.245（17）。在（2）中，有两个戊四酸取代基，其中一个的C基团在两个位置上是无序的，占空度为0.55（2）和0.45（2）。戊-4-酸酯取代基之一处于延长构象，而另一个处于弯曲构象。在该衍生物中，两个4-戊酸酯取代基的平面部分偏离香豆素平面。 （1）的堆积主要由涉及香豆素环的π-π堆积和弱的CH⋯O触点在[101]方向上连接平行的堆积组成。相反，在（2）中，堆积由R22（24）氢键控制，该氢键涉及酸性sp H原子和oxo O原子，它们将分子连接成中心对称的二聚体。戊-4-酸取代基之一的弯曲构型可防止香豆素环参与π-π堆积。

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