The reaction between 3,3'-[(3-meth-oxy-4-hy-droxy-phen-yl)methanedi-yl]bis-(4-hy-droxy-2H-chromen-2-one) and tri-ethyl-amine in methanol yielded the title compound tri-ethyl-ammonium 3-[(4-hy-droxy-3-meth-oxy-phen-yl)(4-hy-droxy-2-oxo-2H-chromen-3-yl)meth-yl]-2-oxo-2H-chromen-4-olate, C6H16N+·C26H17O8- or (NHEt3)+(C26H17O8)-, which crystallized directly from its methano-lic mother liquor. The non-deprotonated coumarol substituent shares its H atom with the deprotonated coumarolate substituent in a short negative charge-assisted hydrogen bond in which the freely refined H atom is moved from its parent O atom towards the acceptor O atom, elongating the covalent O-H bond to 1.18 (3) Å. The respective H atom can therefore be described as being shared by two alcohol O atoms, culminating in the formation of an eight-membered ring.
Keywords: 4-hydroxy-3-methoxyphenyl dicoumarol; 4-hydroxycoumarin derivatives; crystal structure; negative charge-assisted hydrogen bonds; short intramolecular hydrogen bonds.