1,1,2,2-Tetra­kis(dimethyl­amino)­ethane-1,2-diium bis­(tetra­phenyl­borate) acetone disolvate

The title compound, C₁₀H₂₄N₄²⁺·2C₂₄H₂₀B^-·2C₃H₆O, crystallizes with two acetone solvent mol­ecules per asymmetric unit. In the dication, both amidinium units are twisted about the central C-C single bond by 63.8 (3)° and the positive charges are delocalized over both N-C-N planes.

1-Methyl-1,3-diazinan-2-one

In the crystal structure of the title compound, C₅H₁₀N₂O, mol­ecules are connected via pairs of strong N—H...O hydrogen bonds into centrosymmetric dimers, which are stacked along the a axis. The molecule is not planar, the dihedral angle between the N/C/N and C/C/C planes being 42.1(1)°.

3-Phenyl-N,N,N′,N′-tetra­methyl-1-ethyne-1-carboximidamidium bromide

The reaction of 3,3,3-tris­(dimethyl­amino)-1-phenyl­prop-1-yne with bromine in pentane yields the title compound, C₁₃H₁₇N₂⁺·Br⁻. The acetyl­enic bond distance [1.197 (2) Å] is consistent with a C[triple bond]C triple bond. The amidinium C=N bonds [1.325 (2) and 1.330 (2) Å] have double-bond character and the positive charge is delocalized between the two dimethyl­amino groups.

N,N,N′,N′-Tetra­methyl-N′′,N′′-dipropyl­guanidinium chloride–(2Z)-2,3-diamino­but-2-enedinitrile (1/1)

In the crystal structure of the title compound, C₁₁H₂₆N₃⁺·Cl⁻·C₄H₄N₄, the (2Z)-2,3-diamino­but-2-ene-dinitrile (Z-DAMN) mol­ecules are connected with the chloride ions via N—H...Cl hydrogen bonds, forming ribbons running along the a axis. The guanidinium ions are located in between the ribbons formed by Z-DAMN mol­ecules and chloride ions.

2-Dimethylamino-1-(2-ethoxy-2-oxo­ethyl)-3-methyl-3,4,5,6-tetrahydro­pyrimidin-1-ium tetraphenylborate

Isolated guanidinium ions and tetra­phenyl­borate ions are present in the crystal structure of the title compound, C₁₁H₂₂N₃O₂⁺·C₂₄H₂₀B⁻. In the guanidinium ion, the dihedral angle between the N/C/N and C/C/C planes being 49.9 (1)°. The six-membered ring exhibits a half-chair conformation. The C—N bond lengths in the cation range between 1.3335 (16) and 1.3552 (16) Å, indicating charge delocalization on the CN₃ plane. In the crystal, the cations are connected by C—H...O hydrogen bonds, generating a chain along the c axis.

N,N,N',N'-Tetra­methyl-N''-[2-(N',N',N'',N''-tetra­methyl­guanidino)eth­yl]guanidine

The title compound, C₁₂H₂₈N₆, is located about an inversion center situated at the center of the -CH₂-CH₂- bond. The C-N bond lengths are 1.285 (2), 1.384 (2) and 1.395 (1) Å, indicating double- and single-bond character. The N-C-N angles are 114.1 (1), 119.3 (1) and 126.5 (1)°, showing a deviation of both CN₃ planes from an ideal trigonal-planar geometry.

N,N,N′,N′,N′′-Penta­methyl-N′′-[3-(1,3,3-trimethyl­ureido)prop­yl]guanidinium tetra­phenyl­borate

In the crystal structure of the title molecular salt, C₁₃H₃₀N₅O⁺·C₂₄H₂₀B⁻, discrete guanidinium cations and tetra­phenyl­borate anions are present. The C—N bond lengths in the CN₃ unit are 1.3427 (12), 1.3445 (12) and 1.3453 (13) Å, indicating double-bond character. The central C atom is surrounded in a nearly ideal trigonal-planar geometry by three N atoms and the positive charge is delocalized on the CN₃ plane. The bonds between the N atoms and the terminal C-methyl groups all have values close to a typical single bond [1.4595 (15)–1.4688 (12) Å]. In the crystal, cations are connected by C—H...O contacts generating a chain along the c axis.

1-Benzyl-2-dimethyl­amino-3-methyl-3,4,5,6-tetra­hydro­pyrimidin-1-ium bromide

In the title molecular salt, C₁₄H₂₂N₃⁺·Br⁻, the ring incorporating the guanidinium grouping exhibits a half-chair conformation and the dihedral angle between the N—C—N and C—C—C planes is 55.0 (3)°. The C—N bond lengths in the central CN₃ unit are 1.333 (4), 1.338 (3) and 1.341 (4) 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 delocalized in the CN₃ plane. The distances between the N atom and the terminal methyl C atoms [1.453 (4)–1.461 (4) Å] are all close to a typical single C—N bond length.