In this study we have calculated global and local DFT reactivity descriptors for isomeric pyrano-, thiopyrano- and selenopyranopyrroles. The geometric optimization of the obtained structures have been realized with the density functional theory (DFT, B3LYP) at the level of 6-311G(d,p) and show these isomers have planar configurations. The structural properties such as dipole moments, bond lengths and bond angles of these isomers have been calculated. The heats of formation have also been calculated based on the optimized geometry. The energies of HOMO and LUMO molecular orbitals have been used to determine several global descriptors as a measure of their electronic properties, relative stabilities and chemical reactivities. These include total energy (E), ionization potential (I), electron affinity (A), chemical hardness (η), chemical softness (S), electronic chemical potentials (μ) and electrophilicity (ω). Selenopyrano[2,3-c]pyrrole possesses the highest electrophilicity and minimum chemical hardness among the calculated isomeric structures. The largest calculated dipole moment belongs to pyrano[2,3-c]pyrrole, while thiopyrano[3,4-b]pyrrole has the lowest.

中文翻译：

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结构对吡喃吡喃，吡喃吡喃和硒吡喃吡咯的反应活性和稳定性的影响的理论研究

在这项研究中，我们已经计算了吡喃吡咯，吡喃吡喃和硒吡喃吡咯的异构体的整体和局部DFT反应性描述子。用密度泛函理论（DFT，B3LYP）在6-311G（d，p）的水平上实现了所获得结构的几何优化，结果表明这些异构体具有平面构型。已经计算出这些异构体的结构性质，例如偶极矩，键长和键角。还基于优化的几何结构计算了地层热。HOMO和LUMO分子轨道的能量已被用来确定几个全局描述符，以此来衡量它们的电子性质，相对稳定性和化学反应性。其中包括总能量（E），电离势（I），电子亲和力（A），化学硬度（η），化学柔软度（S），电子化学势（μ）和亲电性（ω）。在计算的异构体结构中，硒吡喃并[2,3-c]吡咯具有最高的亲电子性和最低的化学硬度。计算出的最大偶极矩属于吡喃并[2,3-c]吡咯，而硫代吡喃并[3,4-b]吡咯具有最低的偶极矩。