Crystal structure of a polyether dicarboxylic acid complex with potassium picrate, 2, 2′-di- o-carboxymethoxyphenoxydiethyletherpotassium picrate

Abstract

X-ray crystal structure analysis has been carried out on the title compound. In a triclinic unit cell having a = 9.292(9), b = 11.224(3), 3 = 15.000(4)Å, α = 95.4592), β = 99.22(4), γ = 108.15(4)° and space group P 1 , there are two units of formula {K[HOOC CH 2O C 6H 4O CH 2CH 2] 2O} −. Least squares refinement reduced R to 0.0655 for 2210 photographic observations. The hydrogen atoms of the dicarboxylic acid were located unequivocally; one is involved in hydrogen bonding to a centrosymmetrically related carboxylic acid, the other hydrogen bonds the phenolic oxygen of a picrate anion. A centrosymmetrical ▪ bridge formed by a carbonyl oxygen atom holds the complex cation in a dimeric form. The eight coordinating oxygen atoms form a shallow helix round each potassium ion with K O distances 2.729–2.903 Å; there are no intramolecular hydrogen bonds within the helix.