Spectral analysis, structural elucidation and evaluation of chemical reactivity of synthesized ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate through experimental studies and quantum chemical calculations

• The solid state FT-IR spectrum study indicates dimer formation of the compound.
• The reactivity descriptors analysis indicates the suitability of compound for heterocyclic synthesis.
• Quantum Theory of Atoms in Molecules’ (QTAIM) studies confirm intra- and intermolecular hydrogen bond.
• The calculated hyperpolarizabiltiy value indicates applicability as non-linear optical material.

This paper describes the synthesis, spectral analysis, structural elucidation and chemical reactivity of pyrrole hydrazide–hydrazone: ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (ECAHDPC). The 1H, 13C NMR isotropic chemical shifts and electronic absorption spectra have been calculated by GIAO and TD-DFT methods, respectively, and corroborate well with experimental data. The NH proton of the hydrazide–hydrazones (CNNHCO) frame appears as singlet at δ = 11.69 ppm due to delocalization of nitrogen lone pair with carbonyl group and its proton involvement in intramolecular H-bonding. The calculated wavenumbers of dimer are in good agreement with the experimental results and confirm that the stable conformer forms dimer by hydrogen bonding interactions between pyrrolic NH and carbonyl CO group of ester giving red shift and resonance assisted hydrogen bonding. The binding energy of intermolecular interaction is found to be 10.19 kcal/mol after basis set superposition error correction. QTAIM calculations confirm the existence of intermolecular conventional hydrogen bond (NH⋯O), intra and intermolecular non-conventional hydrogen bond (CH⋯O) and intramolecular interaction (C⋯N). The NBO analysis has been performed to evaluate charge transfer and delocalization of electron density. The static first hyperpolarizability (β0) of monomer has been found to be 6.59 × 10–30 esu. The maximum value of reactivity descriptors (fk+, sk+, ωk+) at C(9) indicate that this site is more susceptible to nucleophilic attack, favoring for the formation of heterocyclic compounds.

This paper describes the synthesis, solid state spectral analysis, structural elucidation and chemical reactivity of ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate. Its calculated spectroscopic finding corroborate well with experimental data. The reactivity descriptors analysis indicates it suitability for the formation of 4, 5 and 6 membered heterocyclic compounds.Figure optionsDownload as PowerPoint slide