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Hydrogen Bonding Patterns and pi...pi Interactions in Some Derivatives of 2-substituted indan-1, 3-diones

The unique properties of 2-substituted-indan-1, 3-diones are due to the presence of the indan-1, 3-dione moiety (Scheme ; indane = benzocyclopentane), which is known as a very strong electron acceptor. When it is coupled with electron donating substituents with different strength, the photophysical properties, due to intramolecular charge transfer, of the dipolar molecules can be modulated. On the other hand, the complexation capabilities of these compounds have found practical application as extracting agents for various transition metal ions. 2-Substituted indan-1, 3-dione derivatives with the Csp2atom at position 2 possess intramolecular resonance assisted hydrogen bonds (RAHB) in the -conjugated -dicarbonyl fragment, thus allowing tautomerization via an intramolecular proton transfer process. The geometry of RAHB is as expected with the O•••O distance spanning in the range 2.625(1) Å - 2.650(3) Å [bond angle range 147(2)o – 162(5) o]. The intermolecular hydrogen bonds are of the C-H•••O type and they will be discussed in details as well as pi•••pi interactions.

hydrogen bonds; pi...pi interactions; 2-substituted indan-1; 3-diones

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