Potassium 3-oxo-2,3-dihydro-1H-inden-4-olate: Formation, molecular and electronic structure

• Aldol condensation of 7-hydroxy-1-indanone gives potassium salt as unexpected product.
• X-ray analysis revealed the chelate structure of potassium salt of 7-hydroxy-1-indanone.
• DFT and MP2 molecular structure, vibrational properties, 13C and 1H NMR were discussed.

Unlike 1-indanone, 7-hydroxy-1-indanone does not enter the base-catalyzed condensation reaction with 1H-pyrrole-2-carbaldehyde but, instead, gives the salt, potassium 3-oxo-2,3-dihydro-1H-inden-4-olate dihydrate. X-ray analysis, NMR, IR, UV spectroscopy, DFT and MP2 calculations allowed to prove the chelate structure of the salt and to estimate the effect of chelation on the spectral properties as well as to explain the specific reactivity.