Determination of the molecular packing in the crystal of coumarin by means of potential-energy calculations

Abstract

Coumarin (o-coumaric acid lactone, C9H602) forms orthorhombic crystals, space group Pca21, Z= 4, a= 15.466 (12), b= 5.676 (6), c= 7.917 (6) A. The structure was solved by potential-energy calculations coupled with the minimum residual analysis. Three-dimensional X-ray data were measured with an offline Siemens automatic single-crystal diffractometer by the co-scan technique. The refinement was carried out by least-squares methods and the final R is 0.048. The carbon and oxygen atoms of coumarin lie in the same plane, the greatest deviation being 0.015 A. The crystal packing is characterized mainly by van der Waals and dipole-dipole interactions. However, the dipole-dipole contribution to the total potential energy does not seem to determine the molecular packing.

3-Acetyl-6-bromocoumarin

“…The angles around C(2) in (I) are 119.9 (7), 112.8 (7) and 127.4(7) °, compared with 117.3(3), 117.2(3) and 127.4(7) ° in coumarin (Gavuzzo, Mazza & Giglio, 1974), and resemble the geometry of a carboxylic group; O(2)--C (2) indicates that the packing is stabilized by such C~ H...O interactions, which can be considered as weak hydrogen bonds (Taylor & Kennard, 1982;BerkovitchYeUin & Leiserowitz, 1984). Atomic scattering factors from Cromer & Mann (1968) and Stewart, Davidson & Simpson (1965) (2) 0.410 (2) 0.2249 (7) 0.6296 (7) 2.9 (4) C (3) 0.6096 (19) 0.3262 (7) 0.6029 (7) 2.5 (4) C (4) 0.638 (2) 0.3363 (6) 0.4881 (7) 2.6 (4) C (5) 0.518 (2) 0.2595 (6) 0.2647 (7) 2.8 (4) C (6) 0.3776 (t9) 0.1683 (7) 0.1716 (7) 2.9 (4) C (7) 0.209 (2) 0.0690 (7) 0.2013 (7) 3.0 (4) C (8) 0.181 (2) 0.0597 (7) 0.3194 (7) 3.1 (4) C (9) 0.321 (2) 0.1495 (7) 0.4131 (7) 2.6 (4) C (10) Crystals of (I) were supplied by MVK.…”

Crystal Structure, Mesomorphic and Emission Properties of Liquid Crystals Having a 7-(Diethylamino)-3-phenylcoumarin Core

“…The C-C bond lengths of the coumarin ring of are similar to those of 7-diethylaminocoumarin 27) and 7-diethylamino-3-dimethylaminocoumarin 9) and distinct from those of coumarin itself 28) . The C6-C7 bond length of (I) is longer than that (1.368 (6) Å) of coumarin itself 28) . The C7-N1 bond length is close to that (1.378 (3) Å) of 7-diethylamino-3-dimethylaminocoumarin 9) and (5) 93.1(6)…”

Synthesis, spectroscopic and crystal structure analysis of a compound with pharmocophoric substituent: 2-cyclohexyl-6-(2-oxo-2H-chromen-3-yl)- imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehyde

“…The coumarin skeleton geometry can be compared with that of unsubstituted coumarin. 20 of coumarin-3-carboxylic acid 21 and of 3-(bromoacetyl) coumarin. 22 The double-bond character of C11 -C21 is observed in all these compounds.…”