Crystal structures of N,N-dimethyl-(2-(2,2-diphenyl)-2-prop-2-ynyloxy)acetoxy)ethylamine and N,N-dimethyl-(2-(2,2-diphenyl)-2-prop-2-ynyloxy)acetoxy)ethylammonium 2,4,6-trinitrophenolate

The molecule of the neutral title compound and the cation in the title salt both exhibit a similar kind of disorder, even though their overall conformations are different. There are no direction-specific interactions between the molecules of the neutral compound, but the ions in the salt are linked into hydrogen-bonded sheets.

In the cation of the picrate salt (II) (Fig. 2), the same fragment is disordered, again over two sets of atomic sites, but now with occupancies of 0.654 (11) and 0.346 (11). The physical separation of the two sets of atomic sites is, in general, rather less in (II) than in (I), but the overall conformation of the cation in (II) is different from that of the neutral compound (I). This is well illustrated by the values of the torsion angles O12-C11-C12-O13, 157.8 (2) in (I) and 13.1 (2) in (II), and C11-O11-C2-C1 À 123.1 (4) in (I) and 172.8 (4) in (II), resulting in very different locations for the disordered fragment relative to the fragment Ph 2 COCH 2 CCH (cf. Figs. 1 and 2).
The C-O distance in the picrate anion in (II), 1.2486 (17) Å , is short for its type [mean value (Allen et al., 1987) 1.362 Å , lower quartile value 1.353 Å ]; the C-N distances in this anion, in the range 1.445 (2)-1.459 (2) Å , all fall below the mean value of 1.468 Å for bonds of this type. In addition, the C31-C32 and C31-C36 distances are 1.445 (2) and 1.439 (2) Å , respectively, whereas the other four C-C distances in this ring lie in the range 1.367 (2)-1.385 (2) Å with a mean value of 1.375 Å . These observations point to significant contributions to the electronic structure of this anion of polarized forms in which the negative charge is delocalized from the phenolic O atom into the ring and thence onto the nitro groups as recently noted (Sagar et al., 2017).

Supramolecular features
Despite the abundance of potential hydrogen-bond donors and acceptors in (I), with the C-H bonds of the aryl rings and the alkynyl unit as potential donors, and the amino N atom, the carbonyl O atom, two aryl rings and the triple bond of the alkynyl function as potential acceptors, there are in fact, no hydrogen bonds of any kind in the crystal structure of (I): nor are there any aromaticstacking interactions, so that the structure consists of essentially isolated molecules making only van der Waals-type contacts with one another.
Both disorder components of the cation in (II) are linked to the anion within the selected asymmetric unit via a near planar, but markedly asymmetric three-centre N-HÁ Á Á(O) 2 charge-assisted (Gilli et al., 1994) hydrogen bond (Table 1), which forms an R 2 1 (6) motif. The resulting ion pairs are further linked by three C-HÁ Á ÁO hydrogen bonds into complex sheets: however, the straightforward identification of two simple one-dimensional sub-structures (Ferguson et al., 1998a,b;Gregson et al., 2000) leads to a simple analysis of the The molecular structure of compound (I) showing the atom-labelling scheme and the disorder. Displacement ellipsoids are drawn at the 30% probability level, and the minor disorder component is drawn with broken lines.

Figure 2
The ionic components of compound (II) showing the atom-labelling scheme and the disorder. Displacement ellipsoids are drawn at the 30% probability level, and the minor disorder component is drawn with broken lines.
sheet formation. In the simpler of the two sub-structures, the C-HÁ Á ÁO hydrogen bond involving an aryl C-H unit links ion pairs related by translation along [100] into a C 1 2 (12) chain (Fig. 3). In the second sub-structure, the cooperative effect of two C-HÁ Á ÁO hydrogen bonds, both involving CH 2 groups, generates a chain parallel to [110] containing alternating R 2 1 (6) and R 2 2 (11) rings (Fig. 4). The combination of these two chain motifs generates a sheet lying parallel to (001) in the domain 0.5 < z < 1.0: a second such sheet, related to the first by inversion, lies in the domain 0 < z < 0.5, but there are no direction-specific interactions between adjacent sheets.

Database survey
In the (2R,3R)-(hydrogentartrate) salt (III) , the cation is fully ordered, unlike that in the picrate (II) and the conformation of the cation closely resembles that of the neutral molecule (I).
The anions are linked by three O-HÁ Á ÁO hydrogen bonds to form sheets lying parallel to (001) and containing equal numbers of R 2 2 (7) and R 4 4 (21) rings (Fig. 5) Part of the crystal structure of compound (II) showing the formation of a hydrogen-bonded chain running parallel to [100]. For the sake of clarity, only the major disorder component of the cation is shown and the H atoms not involved in the motif shown have been omitted. The atoms marked with an asterisk (*) and a hash (#) are at the symmetry positions (À1 + x, y, z) and (1 + x, y, z), respectively.

Figure 4
Part of the crystal structure of compound (II) showing the formation of a hydrogen-bonded chain of rings running parallel to [110]. For the sake of clarity, only the major disorder component of the cation is shown and the H atoms bonded to the C atoms which are not involved in the motif shown have been omitted. The atoms marked with an asterisk (*) and a hash (#)are at the symmetry positions (1 + x, À1 + y, z) and (À1 + x, 1 + y, z), respectively. Table 1 Hydrogen-bond geometry (Å , ) for (II).  (Fig. 6). 4-(2,2-Diphenyl-2-propoxyacetoxy)-1-methylpiperidin-1ium picrate (propiverinium picrate) (IV) is closely related to compound (II), differing in containing a saturated alkoxy substituent and having an N-methyl piperidinium unit in place of the N,N-dimethylethylammonium unit in (II). The component anions in (IV) are linked (Jasinski et al., 2009) by the same type of hydrogen-bonded (R 2 1 6) ring as seen in (II) but there are no structurally significant interactions between adjacent ion pairs in (IV).

Synthesis and crystallization
A sample of compound (I) was a gift from RL Fine Chem, Pvt. Ltd., Bengaluru, India, and it was recrystallized from methanol solution by slow evaporation at room temperature, m.p. 347-351 K. For the preparation of compound (II), equimolar quantities (0.30 mmol) of (I) and picric acid were dissolved in hot methanol and the solution was held at 333 K for 0.5 h, with magnetic stirring throughout. The solution was then allowed to cool slowly to room temperature, giving crystals of (II) suitable for single-crystal X-ray diffraction. m.p. 386-389 K.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. It was apparent from an early stage in the refinements that in both (I) and (II) the dimethylaminoethyl portion was disordered over two sets of atomic sites having different occupancies in each case, and corresponding to different conformations. For the minor conformation of each compound, the bonded distances and the 1,3-non-bonded distances were restrained to be the same as the corresponding distances in the major conformer, subject to s.u.s of 0.005 and 0.01 Å , respectively: in addition, the anisotropic displacement parameters for corresponding pairs of atomic sites occupying essentially the same physical space were constrained to be equal. All H atoms, other than those in the minor disorder components, were located in difference maps, and then treated as riding atoms in geometrically idealized position, with distances C-H 0.93 Å (aromatic and alkyne), 0.96 Å (CH 3 ) or 0.97 Å (CH 2 ) and N-H 0.98 Å , with U iso (H) = kU eq (carrier), where k = 1.5 for the methyl groups, which were permitted to rotate but not to tilt, and 1.2 for all other H atoms. The H atoms in the minor disorder components were included in calculated positions using the same procedure. When the refinement of the atomic coordinates for the H atoms bonded to N atoms in (II) was attempted, the resulting N-H distances were 1.04 (4) and 0.82 (8) Å : accordingly, the riding model was preferred. Two low-angle reflections which had been attenuated by the beam stop, (020) for (I) and (002)    )] for the group of 518 very weak reflections having F c /F c (max) in the range 0.000 < F c /F c (max) < 0.004, and for (II) a value of K = 9.509 for the group of 789 very weak reflections having F c /F c (max) in the range 0.000 < F c /F c (max) < 0.006.   used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015) and PLATON (Spek, 2009).  (2) Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

N,N-Dimethyl-[2-(2,2-diphenyl)-2-prop-2-ynyloxyacetoxy]ethylamine (I)
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 ) 125.0 (2) C135-C136-H136 120.0 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.