Molecular structures in which intramolecular hydrogen bonding, IHB, engaged into π-electron delocalization, PED, are interesting structures bridging their different specifications in a way that the accuracy of each can be evaluated against the other. In the present study, PED properties and IHB strength of a β-diketone series, with special emphasis on 2-furoylacetone, FA, have been investigated. The coexistence of two enol tautomers in FA is very likely, with IHB energies of about 18–21 kcal/mol. Enolic proton chemical shift of 15.5/15.15 ppm (experimental/theoretical), also OH stretching vibration of 3019 cm−1 (theoretical), indicate the relatively strong IHB of FA. It is demonstrated that detailed analyses of charge distributions provide valuable insight into PED. β-substitutions with electron-withdrawing character increase PED in C-C=C segment of molecule, while decrease PED in the chelated ring. It is confirmed that IHB strengths do not correlate with the PED, in contrary with the concept of resonance assisted H-bonding.

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