Suramitr Songwut, Teanwarawat Jitpinan, Ithiapa Nuttapong, Wattanathana Worawat, Suramitr Anwaraporn
Department of Chemistry, Faculty of Science and Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, KU Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
Department of Materials Engineering, Faculty of Engineering, Kasetsart University 10900, Thailand.
Acta Crystallogr E Crystallogr Commun. 2020 Jun 5;76(Pt 7):1027-1032. doi: 10.1107/S2056989020007197. eCollection 2020 Jul 1.
The mol-ecular structure of the title compound {systematic name: 3',6'-bis(di-ethyl-amino)-2-[(2-hy-droxy-benzyl-idene)amino]-spiro-[isoindoline-1,9'-xan-then]-3-one}, CHNO or RbSa, can be seen as being composed of two parts sharing a central quaternary carbon atom. Both the xanthene and iso-indole moieties are nearly planar: 14 atoms in the former moiety show an r.m.s. deviation of 0.0411 Å and eleven atoms in the latter moiety show an r.m.s. deviation of 0.0545 Å. These two planes are almost perpendicular to each other, the angle between the mean planes being 87.71 (2)°. The title compound appears to be in its enol form. The corresponding H atom was located and freely refined at a distance of 1.02 (3) Å from the O atom and 1.72 (2) Å from the N atom. The strong intra-molecular hydrogen bond O-H⋯N bridging the hydroxyl group and its neighboring nitro-gen atom forms an (6) graph-set motif. Apart from the intra-molecular O-H⋯N hydrogen bond, C-H⋯O inter-actions are observed between two neighbouring RbSa mol-ecules related by an inversion center. The C-O donor-acceptor distance is 3.474 (2) Å. Moreover, C-H⋯π inter-actions are observed between the C-H bond of one of the ethyl groups and the centroid of the benzene ring of the iso-indole moiety. The C⋯centroid distance is 3.8191 (15) Å. No π-π inter-actions are observed in the crystal structure as the shortest distance between ring centroids is more than 4 Å. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H, C⋯H/H⋯C, O⋯H/H⋯O and N⋯H/H⋯N inter-actions. DFT calculations at the CAM-B3LYP/6-31 G() level were carried out to gain a better understanding of the relative energies and the tautomerization process between two possible conformers (keto and enol), as well as the transition state of the title compound.
标题化合物{系统名称：3',6'-双（二乙氨基）-2-[(2-羟基亚苄基)氨基]-螺[异吲哚啉-1,9'-呫吨]-3-酮}，CHNO或RbSa的分子结构可视为由共享一个中心季碳原子的两部分组成。呫吨和异吲哚部分几乎都是平面的：前一部分中的14个原子的均方根偏差为0.0411 Å，后一部分中的11个原子的均方根偏差为0.0545 Å。这两个平面几乎相互垂直，平均平面之间的夹角为87.71(2)°。标题化合物似乎处于其烯醇形式。相应的H原子位于距O原子1.02(3) Å和距N原子1.72(2) Å处，并进行了自由精修。连接羟基及其相邻氮原子的强分子内氢键O-H⋯N形成了一个(6)图集 motif。除了分子内的O-H⋯N氢键外，在通过对称中心相关的两个相邻RbSa分子之间观察到C-H⋯O相互作用。C-O供体-受体距离为3.474(2) Å。此外，在一个乙基的C-H键与异吲哚部分苯环的质心之间观察到C-H⋯π相互作用。C⋯质心距离为3.8191(15) Å。在晶体结构中未观察到π-π相互作用，因为环质心之间的最短距离超过4 Å。对晶体结构的Hirshfeld表面分析表明，晶体堆积的最重要贡献来自H⋯H、C⋯H/H⋯C、O⋯H/H⋯O和N⋯H/H⋯N相互作用。在CAM-B3LYP/6-31 G()水平上进行了DFT计算，以更好地理解两种可能构象（酮式和烯醇式）之间的相对能量和互变异构过程，以及标题化合物的过渡态。
