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Updated: May 13, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Bis-(3,5-diamino-4H-1,2,4-triazol-1-ium) 3,4-dioxocyclo-butane-1,2-diolate
Hoong-Kun Fun1, Wan-Sin Loh, Atim Johnson
1X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia ; Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia.
Abstract:
The asymmetric unit of the title compound, 2C2H6N5(+)·C4O4(2-), contains two 3,5-diamino-4H-1,2,4-triazolium cations and one squarate dianion. The squaric acid mol-ecule donated one H atom to each of the two 3,5-diamino-1,2,4-triazole mol-ecules at their N atoms. The squaric acid dianion has four C-O bonds which are shorter than a normal single C-O bond (1.426 Å) and are slightly longer than a normal C=O bond (1.23 Å), which indicates the degree of electron delocalization in the dianion. In the crystal, the cations and dianions are linked by N-H⋯N and N-H⋯O hydrogen bonds into a three-dimensional network.
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