Crystal structures of ethyl 6-(4-methylphenyl)-4-oxo-4H-chromene-2-carboxylate and ethyl 6-(4-fluorophenyl)-4-oxo-4H-chromene-2-carboxylate

• Type: Article in International Scientific Journal
• Date: 2016

Authors

Gomes, LR (Author) Other; Low, JN (Author) Other; Fernandes, C (Author) Other; Gaspar, A (Author) Other; Fernanda Borges (Author) FCUP

Journal

Title: Acta Crystallographica Section E: Crystallographic Communications

Vol. 72

Pages: 8-+

Publisher: International Union of Crystallography

Indexing

ISI Web of Knowledge - 2 Citations

Scopus - 1 Citation

Other information

Authenticus ID: P-00K-3S4

DOI: 10.1107/s2056989015022781

Abstract (EN): The crystal structures of two chromone derivatives, viz. ethyl 6-(4-methylphenyl)-4-oxo-4H-chromene-2-carboxylate, C19H16O4, (1), and ethyl 6-(4-fluorophenyl)-4-oxo-4H-chromene-2-carboxylate C18H13FO4, (2), have been determined: (1) crystallizes with two molecules in the asymmetric unit. A comparison of the dihedral angles beween the mean planes of the central chromone core with those of the substituents, an ethyl ester moiety at the 2-position and a para-substituted phenyl ring at the 6-position shows that each molecule differs significantly from the others, even the two independent molecules (a and b) of (1). In all three molecules, the carbonyl groups of the chromone and the carboxylate are trans-related. The supramolecular structure of (1) involves only weak C-H center dot center dot center dot pi interactions between H atoms of the substituent phenyl group and the phenyl group, which link molecules into a chain of alternating molecules a and b, and weak pi-pi stacking interactions between the chromone units. The packing in (2) involves C-H center dot center dot center dot O interactions, which form a network of two intersecting ladders involving the carbonyl atom of the carboxylate group as the acceptor for H atoms at the 7-position of the chromone ring and from an ortho-H atom of the exocyclic benzene ring. The carbonyl atom of the chromone acts as an acceptor from a meta-H atom of the exocyclic benzene ring. pi-pi interactions stack the molecules by unit translation along the a axis.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 18