Structure and absolute configuration of viocidic acid: X-ray analysis of viocidic acid dihydrobromide

The constitution and absolute stereochemistry of viocidic acid, a degradation product of viomycin, has been established by an X-ray crystal structure analysis of its dihydrobromide, C8H13N5O2,2HBr,3H2O. Crystals are orthorhombic, space group P212121, with Z= 4 in a unit cell of dimensions a= 8·17, b= 12·17, c= 15·22 A. The atomic co-ordinates were determined by Fourier and least-squares calculations and the final R value was 7·6% for 1408 independent reflexions. The structure comprises dipositive C8H15N5O2 ions, bromide ions, and water molecules; hydrogen bonding is the dominant feature of the intermolecular packing.