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.

In the title compound, C 17 H 21 N 3 O, 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 CN 3 plane from an ideal trigonal-planar geometry. In the crystal, non-classical C-HÁ Á ÁO hydrogen bonds between methyl H atoms and methoxy O atoms are present, generating centrosymmetric dimers running in the [101] direction.

Comment
The here presented title compound is similar to the structurally known compound N′′-phenyl-N,N-dimethyl-N′,N′-methylphenyl-guanidine (Tanatani et al., 1998). According to the structure analysis, the C1-N3 bond in the guanidine unit is

Experimental
One equivalent of N,N-dimethyl-N′,N′-methylphenyl-chloroformamidinium-chloride (synthesized from N,N-dimethyl-N′,N′-methylphenylthiourea and phosgene) was reacted with one equivalent of 4-methoxyaniline (Sigma-Aldrich) in acetonitrile, in the presence of one equivalent of triethylamine, at 273 K. The obtained mixture consisting of the guanidinium chloride and triethylammonium chloride was reacted in the next step with an excess of an aqueous sodium hydroxide solution at 273 K. After extraction of the guanidine with diethyl ether from the water phase, the solvent was evaporated and the title compound was isolated in form of a colourless solid. Single crystals have been obtained by recrystallization from a saturated acetonitrile solution at 273 K.

Refinement
The hydrogen atoms of the methyl groups were allowed to rotate with a fixed angle around the C-N and C-O bond to best fit the experimental electron density, with U iso (H) set to 1.5 U eq (C) and d(C-H) = 0.96 Å. The H atoms in aromatic rings were placed in calculated positions with (C-H) = 0.93 Å. They were included in the refinement in the riding model approximation, with U iso (H) set to 1.2U eq (C).  The structure of the title compound with atom labels and 50% probability displacement ellipsoids.

Figure 2
Non-classical C-H···O hydrogen bonds (indicated by dashed lines) between the methyl hydrogen atoms (H17A) and oxygen atoms (O1) of the methoxy groups, forming a centrosymmetric dimer.  Packing diagram of the title compound in ac-plane. The hydrogen bonds are indicated by dashed lines.  (12) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.