ORIGINAL PAPER Synthesis, Crystal Structure, Ab Initio Studies and Fingerprint Plots of 2-Chloro-1,3-dioxo-2,3-dihydro-1H-inden-2-yl acetate Raza Murad Ghalib • Rokiah Hashim • P. S. Pereira Silva • Sayed Hasan Mehdi • Othman Sulaiman • Manuela Ramos Silva Received: 3 May 2011 / Accepted: 29 June 2011 / Published online: 17 July 2011 Ó Springer Science+Business Media, LLC 2011 Abstract 2-Chloro-1,3-dioxo-2,3-dihydro-1H-inden-2-yl acetate, C 11 H 7 ClO 4 (Fig. 1), has been synthesized and the structure has been solved by IR and X-ray diffraction studies. The crystals are triclinic, space group P  1, with a = 7.62060(10) A ˚ , b = 11.5944(2) A ˚ , c = 13.0753(3) A ˚ , a = 97.2820(10)°, b = 101.5740(10)°, c = 101.7930 (10)°, Mr = 238.62, V = 1090.82(3) A ˚ 3 , Z = 4 and R = 0.0557. In the title compound there are two molecules in the asymmetric unit. The molecules are linked via weak C–HÁÁÁO hydrogen bonds forming R 4 4 (28) rings. The inter- molecular interactions were analysed by means of the fin- gerprint plots derived from the Hirshfeld surfaces. The fingerprint plots evidenced subtle differences in the inter- molecular contacts for the two independent molecules. Keywords Synthesis Á Crystal structure Á 2-Chloro-1,3- dioxo-2,3-dihydro-1H-inden-2-yl acetate Á Ab initio calculations Á Fingerprint plots Introduction In this work, we report the synthesis and the crystal struc- ture of molecule (Fig. 1), as determined by spectral analysis and single-crystal X-ray analysis. To investigate the effect of the intermolecular interactions in the conformation of the molecule we have performed the optimization of the geometry of the isolated molecule using Hartree–Fock (HF) and density functional theory (DFT) calculations. In this article we used the CrystalExplorer software [1] to calculate the two-dimensional (2D) fingerprint plots, to elucidate the different crystal environments of the two independent molecules. Such graphical tools based on Hirshfeld surfaces [2, 3] and on the derived 2D fingerprint plots [4, 5] are a valuable tool for visualizing and analyzing intermolecular interactions in polymorphs as well as crystal structures with more than one molecule in the asymmetric unit (Z 0 [ 1). This molecule may be a primary moiety for the synthesis of heterocyclic multi ring compounds. Experimental Materials and Physical Measurements Ninhydrin and acetic anhydride were obtained from Sigma- Aldrich. The solvents and HCl were of AR grade and obtained from Merck. All materials were used without fur- ther purification. The melting point was taken on Thermo Fisher digital melting point apparatus of IA9000 series and is uncorrected. IR spectrum was taken on Shimadzu IR-408 Perkin Elmer 1800 (FTIR). Synthesis of the Title Compound Ninhydrin (1.78 g) was well dissolved in acetic anhydride (5 mL); and HCl (1.50 mL) was added drop wise in the mixture with continuous shaking. The conversion was monitored by TLCs. The resultant reaction mixtures was poured in a beaker and left open in a fuming chamber for slow evaporation to give the transparent crystals of title compound (I) which filtered and washed with chloroform. R. M. Ghalib (&) Á R. Hashim Á S. H. Mehdi Á O. Sulaiman School of Industrial Technology, Universiti Sains Malaysia, Minden, 11800 Pulau Pinang, Malaysia e-mail: raza2005communications@gmail.com P. S. Pereira Silva Á M. R. Silva CEMDRX, Physics Department, University of Coimbra, 3004-516 Coimbra, Portugal 123 J Chem Crystallogr (2011) 41:1688–1693 DOI 10.1007/s10870-011-0158-8