Synthesis, spectral and RAHB studies on some arylhydrazones of β-diketones: crystal and molecular structures of 2-(2-(3-pyridyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione and 2-(2-(2-methoxyphenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione

Abstract

The present study describes the synthesis and spectral analysis of a series of arylhydrazones of β-diketones (1–6) along with the single crystal X-ray structural studies of 2-(2-(3-pyridyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (3) and 2-(2-(2-methoxyphenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (6). Spectral and structural studies clearly exemplify the effective intramolecular hydrogen bonding and as a result the NH proton signals and carbonyl carbon signals are shifted to higher frequency region in NMR spectra. Structural implications imposed by the formation of pseudo six-membered ring after hydrogen bonding is well observed in XRD analysis. XRD analysis also evidences the envelop conformation of the dimedone ring in both the cases and resonance assisted hydrogen bonding (RAHB) studies were also performed.