Crystal structure of the triethylammonium salt of 3-[(4-hydroxy-3-methoxyphenyl)(4-hydroxy-2-oxo-2H-chromen-3-yl)methyl]-2-oxo-2H-chromen-4-olate

Abstract

The reaction between 3,3′-[(3-methoxy-4-hydroxyphenyl)methanediyl]bis(4-hydroxy-2H-chromen-2-one) and triethylamine in methanol yielded the title compound triethylammonium 3-[(4-hydroxy-3-methoxyphenyl)(4-hydroxy-2-oxo-2H-chromen-3-yl)methyl]-2-oxo-2H-chromen-4-olate, C6H16N+·C26H17O8− or (NHEt3)+(C26H17O8)−, which crystallized directly from its methanolic 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

• crystal structure
• 4-hydroxy-3-methoxyphenyl dicoumarol
• 4-hydroxycoumarin derivatives
• negative charge-assisted hydrogen bonds
• short intramolecular hydrogen bonds