Solid-State structure of free base guanidine achieved at last

A study was conducted to investigate the first single-crystal structure determination of the free base guanidine and its hydrogen-bonded molecular network. The study also compared the structural details with the predicted structures and those molecular structures known from guanidine co-crystals. Diffraction experiments at 100, 150, 200, 250, and 270 K confirmed that guanidine failed to achieve any phase transition in this range. The crystal and molecular structures at 100 K based on intensity data of elevated resolution were also described. It was observed that pure guanidine crystallized in the space group Pbca with two independent Y-shaped molecules in the asymmetric unit along with a total of 16 molecules in the unit cell. The study concluded that the molecule consisted a central C atom to which one imino group (NH) and two amino groups (NH2) were covalently bonded.