Revision of the crystal structure of `bis-(glycine) squaric acid'

摘要

The crystal structure of `bis-(glycine) squaric acid' [Tyagi et al. (2016 ). RSC Adv . 6 , 24565–24576], is revised. Re-refinement of the structure against the original X-ray intensity data after correct placement of the donor H atoms proves that the compound is in fact the previously reported diglycinium squarate [systematic name: bis-(carb-oxy-methanaminium) 3,4-dioxo-cyclo-but-1-ene-1,2-diolate; Anio?a et al. (2014 ). New J. Chem. 38 , 3556–3568]. The findings are consistent with the p K a rule.