Crystal Structure and Quantum Chemical Calculations of 2‐(2′‐Oxospiro[1,3‐dioxolane‐2,3′‐indol]‐1′( <scp> 2′ <i>H</i> </scp> )‐yl) acetohydrazide

ABSTRACT The current work describes the synthesis and comprehensive characterization of a newly studied 2‐oxindole derivative, designed through a three‐step process involving condensation, alkylation, and aminolysis reactions. The title compound was rigorously characterized using elemental analysis, 1 H and 13 C‐NMR spectroscopy, as well as single‐crystal X‐ray diffraction analysis revealing a stable spirocyclic structure. The X‐ray experimental data revealed the formation of an extensive 3D intermolecular hydrogen bonding network involving mostly the hydrazine moieties and the carbonyl oxygen atoms. In parallel, quantum chemical calculations (DFT) were performed at the B3LYP/6‐31G(d,p) theoretical level to elucidate the compound's electronic properties. The findings indicate that replacing the carbonyl functional group with a dioxolane ring to form the spirocyclic structure increases the overall stability of the title compound and also shifts it to be more nucleophilic as evidenced by HOMO‐LUMO energy gaps (Δ E = 4.59 eV) and global reactivity descriptors (such as electronegativity χ = 3.76 eV) for the title compound, compared to its structurally similar compound (Δ E = 3.16 eV and χ = 4.84 eV). Notably, the global descriptors demonstrate nucleophilic attack sites, aligning with experimental observations. The overall results highlight the compound's unique spiro architecture and provide insights into its reactivity for future applications in heterocyclic chemistry and drug design. Through integrated experimental and computational analysis, this study provides a validated platform for designing bioactive spirooxindole derivatives with tailored properties.