Bis(phenyl)-1-carbamoylguanidinium N-Phenylcarbamidonitrilate. Revision of an Earlier Proposal

Further refinement of the X-ray diffraction structure factors from the purported neutral molecular complex of 1,5-diphenylbiuret and phenylcarbamidonitrile shows that this material is actually the title salt, C₁₄H₁₅N₄O⁺.C₈H₆N₃O^-, [IUPAC name: 1-phenyl-3-(N-phenylcarbamoyl)guanidinium 3-phenyl-1-ureidonitrilate]. The vital clue was that one of the postulated C-O bond lengths in the presumed 1,5-diphenylbiuret component was too long for a carbonyl group; then unconstrained refinement, without any assumptions, showed both that proton transfer had occurred and that the cation was bis(phenyl)-1-carbamoylguanidinium, the postulated C-O group having been replaced by C-NH₂.

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