In the title salt, C16H34N5O3 (+)·C24H20B(-), the C-N bond lengths in the cation are 1.3368 (16), 1.3375 (18) and 1.3594 (17) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry and the positive charge is delocal-ized in the CN3 plane. In the crystal, weak C-H⋯O contacts are observed between neighbouring guanidinium ions and between guanidinium ions and tetra-phenyl-borate anions. In addition, C-H⋯π inter-actions involving guanidinium H atoms and aromatic rings of the anion are present. The phenyl rings form aromatic pockets, in which the cations are embedded. This leads to the formation of a two-dimensional supramolecular pattern along the ab plane.
Keywords: C—H⋯O contacts; C—H⋯π interactions; crystal structure; salt; tetraphenylborate; ureidoalkylguanidinium.