Determination of an organic crystal structure with the aid of topochemical and related considerations: correlation of the molecular and crystal structures of α-benzylidene-γ-butyrolactone and 2-benzylidenecyclopentanone with their solid state photoreactivity
Determination of an organic crystal structure with the aid of topochemical and related considerations: correlation of the molecular and crystal structures of α-benzylidene-γ-butyrolactone and 2-benzylidenecyclopentanone with their solid state photoreactivity
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借助拓扑化学和相关考虑因素测定有机晶体结构：α-亚苄基-γ-丁内酯和 2-亚苄基环戊酮的分子和晶体结构与其固态光反应性的相关性
DOI：
10.1098/rspa.1985.0009
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
G. Desiraju
中科院分区：
文献类型：
--
作者：
S. Kearsley;G. Desiraju
α-亚苄基-γ-丁内酯2的晶体结构可以借助原子-原子成对能量评估程序来确定，因为其（先前报道的）固态光反应性与拓扑化学原理相结合，极大地限制了分子在晶胞中可能取向的数量。内酯2晶体属单斜晶系，空间群为P21/n，Z = 4，a = 11.014（2），B = 5.959（1），c = 14.286（5），β = 108.05（2）。对846个非零反射的细化导致R（可靠性）为0.046。相比之下，等电子酮2-亚苄基环戊酮（3）具有光稳定性，并在同一空间群中结晶，Z = 4，a = 7.466（4），B = 6.821（4），c = 19.005（1），β = 94.14（1）。3的结构通过直接方法解析，并在1037个非零反射上精修至0.036的R。这两种结构之间的差异可以根据分子内构象和弱C-H来合理化。. . O氢键。这两种化合物的固态光反应性的差异可以与最近邻分子上的“潜在反应性”双键之间的轨道重叠程度有关，所述双键通过反转而相关。化合物2在固态下进行拓扑化学反应，但不拓扑地显示方向偏好，而具有减少的轨道重叠的3是光稳定的。
The crystal structure of α-benzylidene-γ-butyrolactone 2, can be determined with the aid of atom-atom pairwise energy evaluation procedures, because its (previously reported) solid state photoreactivity coupled with topochemical principles, greatly restricts the number of possible orientations of the molecule in the unit cell. Crystals of lactone 2 are monoclinic with space group P21/n and with Z = 4, a = 11.014(2), b = 5.959(1), c = 14.286(5), β = 108.05(2). Refinement on 846 non-zero reflections led to an R (reliability) of 0.046. In contrast, the isoelectronic ketone 2-benzylidenecyclopentanone (3) is photostable, and crystallizes in the same space group with Z = 4, a = 7.466(4), b = 6.821(4), c = 19.005(1), β = 94.14(1). The structure of 3 was solved by direct methods and refined on 1037 non-zero reflections to an R of 0.036. The difference between the two structures can be rationalized in terms of intramolecular conformation and weak C-H. . . O hydrogen bonding. Differences in the solid state photoreactivities of the two compounds can be related to the extent of orbital overlap between ‘potentially reactive’ double bonds on nearest neighbour molecules that are related by inversion. Compound 2 reacts in the solid state topochemically but not topotactically showing directional preference, while 3, which has reduced orbital overlap, is photostable.