3-Methyl-4,5-di­hydro­oxazolium tetra­phenyl­borate

In the cation of the title salt, C₄H₈NO⁺·C₂₄H₂₀B⁻, the C—N bond lengths are 1.272 (2), 1.4557 (19) and 1.4638 (19) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.3098 (19) Å shows that double-bond character and charge delocalization occurs within the NCO plane of the cation. In the crystal, a C—H...π inter­action is present between the methyl­ene H atom of the cation and one phenyl ring of the tetra­phenyl­borate ion. The latter forms an aromatic pocket in which the cation is embedded.

(Meth­oxy­methyl­idene)di­methyl­aza­nium tetra­phenyl­borate aceto­nitrile monosolvate

In the cation of the title salt, C₄H₁₀NO⁺·C₂₄H₂₀B⁻·C₂H₃N, the C—N bond lengths are 1.2864 (16), 1.4651 (17) and 1.4686 (16) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2978 (15) Å shows double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. C—H...π inter­actions are present between the methine H atom and two of the phenyl rings of the tetra­phenyl­borate ion. The latter forms an aromatic pocket in which the cation is embedded. The iminium ion is further connected through a C—H...N hydrogen bond to the aceto­nitrile mol­ecule. This leads to the formation of a two-dimensional supramolecular pattern along the bc plane.

(But­oxy­methyl­idene)di­methyl­aza­nium tetra­phenyl­borate aceto­nitrile monosolvate

In the title solvated salt, C₇H₁₆NO⁺·C₂₄H₂₀B⁻·C₂H₃N, the C—N bond lengths in the cation are 1.2831 (19), 1.467 (2) and 1.465 (2) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2950 (18) Å shows a double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. The two C atoms of the n-butyl group are disordered over the two sites, with refined occupancy ratios of 0.890 (5):0.110 (5) and 0.888 (4):0.112 (4). In the crystal, C—H...π inter­actions occur between the methine H atom, H atoms of the –N(CH₃)₂ and –CH₂ groups of the cation, and two of the phenyl rings of the tetra­phenyl­borate anion. The latter inter­action forms an aromatic pocket in which the cation is embedded. Thus, a two-dimensional pattern is created in the ac plane.

N′′-(4-Meth­oxy­phen­yl)-N,N,N′-trimethyl-N′-phenyl­guanidine

In the title compound, C₁₇H₂₁N₃O, the C—N bond lengths in the guanidine unit are 1.2889 (19), 1.3682 (19) and 1.408 (2) Å, indicating double- and single-bond character. The N—C—N angles are 115.10 (13), 119.29 (15) and 125.61 (14)°, showing a deviation of the CN₃ plane from an ideal trigonal–planar geometry. In the crystal, non-classical C—H...O hydrogen bonds between methyl H atoms and meth­oxy O atoms are present, generating centrosymmetric dimers running in the [101] direction.

N,N,N′-Trimethyl-N′′-(4-nitro­phen­yl)-N′-phenyl­guanidine

The C—N bond lengths in the guanidine unit of the title compound, C₁₆H₁₈N₄O₂, are 1.298 (2), 1.353 (2) and 1.401 (3) Å, indicating double- and single-bond character. The N—C—N angles are 115.81 (16), 118.90 (18) and 125.16 (18)°, showing a deviation of the CN₃ plane from an ideal trigonal–planar geometry. In the crystal, C—H...O hydrogen bonds are observed between the methyl- and aromatic-H atoms and nitro-O atoms. One H atom of the phenyl ring and of the NMe₂ group associate with the O atoms of the nitro group, giving chains along the a- and b-axis directions. Cross-linking of these two chains results in a two-dimensional network along bc.