Crystal structures of (N-methyl-N-phenylamino)(N-methyl-N-phenylcarbamoyl)sulfide and the corresponding disulfane

(N-Methyl-N-phenylcarbamoyl)(N-methyl-N-phenylamino)sulfide and the corresponding disulfane are stable derivatives of (chlorocarbonyl)sulfenyl chloride and (chlorocarbonyl)disulfanyl chloride, respectively.


Chemical context
As part of a multifaceted program in synthetic and mechanistic organosulfur chemistry (Barany et al., 1983;Barany & Mott, 1984;Schroll & Barany, 1986;Schrader et al., 2011, and references cited therein), we frequently encounter challenging-to-characterize compounds with one or more reactive acid chloride and/or sulfenyl chloride moieties. These are converted to the corresponding stable carbamoyl and/or sulfenamide derivatives, which are often crystalline, through their reliable, rapid, and high-yield reactions with N-methylaniline.
The present paper reports the structures of two such derivatives, i.e. (N-methyl-N-phenylamino)(N-methyl-N-phenylcarbamoyl)sulfide (I) and (N-methyl-N-phenylamino)(Nmethyl-N-phenylcarbamoyl)disulfane (II), as determined by X-ray crystallography. The title compounds are derived respectively from (chlorocarbonyl)sulfenyl chloride and (chlorocarbonyl)disulfanyl chloride, which are noxious, distillable liquids. They are the first two members of a general family of compounds with the structure Ph(Me)N(C O)S n N(Me)Ph, in which the higher members (n = 3-6) were found, but not isolated in crystalline form, as components in the reactions of in situ generated (2-propoxydichloromethyl)(chlorocarbonyl)polysulfanes with N-methylaniline (Schroll & Barany, 1986).

Structural commentary
The title compounds differ by the number of sulfur atoms: one in (I) (Fig. 1) versus two in (II) (Fig. 2), and by the resulting ISSN 2056-9890 relative orientations of the Ph(Me)N(C O)S and N(Me)Ph moieties. Otherwise, they share similar bond lengths and angles across all analogous bonds (Table 1). Furthermore, the molecular parameters are all within expected ranges. The S-S bond of (II) is 2.0625 (5) Å , which is comparable to the bond length in elemental sulfur, S 8 (2.07 Å ), but slightly longer than the 2.03 Å found for bis (N-methyl-N-phenylcarbamoyl) (Schroll et al., 2012). In compound (III) (Fig. 3), the slight shortening of the S-S bond was attributed to a partial double-bond character imparted by the adjacent carbonyl groups. Because (II) is essentially (III) minus one carbonyl group, it is not surprising for the S-S bond length in (II) to be closer to that in S 8 . The torsion angle about the S-S bond in (II) is À92.62 (6) , which is comparable to the theoretical optimum of 90 (Pauling, 1949;Torrico-Vallejos et al., 2010).

Supramolecular features
The unit cell of (I) contains two molecules related by a twofold screw axis (Fig. 4). There are no intermolecular contacts in the crystal structure of (I). In the crystal of (II) non-classical intermolecular C7-HÁ Á ÁO1 hydrogen bonds (Table 2) form centrosymmetric cyclic dimers [graph set R 2 2 (10)]. Chains of molecules extending along the b axis result from inter-dimer C2-HÁ Á ÁS1 interactions (Fig. 5).

Database survey
A search for similar structures in the Cambridge Structural Database (CSD; Version 5.36, update of November 2014; Groom & Allen, 2014) gave bis(N-methyl-N-phenylcarbamoyl)disulfane (III), published previously from our research (Schroll et al., 2012), as well as two similar bis(carbamoyl)disulfanes (Bereman et al., 1983;Li et al., 2006)  The molecular conformation of compound (I), showing 50% probability displacement ellipsoids with all non-H atoms labeled and numbered.

Figure 2
The molecular conformation of compound (II), showing 50% probability displacement ellipsoids with all non-hydrogen atoms labeled and numbered.

Figure 4
Crystal packing of (I). H atoms are not shown.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. Hydrogen atoms were included at calculated positions [C-H(aromatic) = 0.95 Å or C-H(methyl) = 0.98 Å ] and treated as riding, with U iso H = 1.2U eq C(aromatic) or 1.5U eq C(methyl). With (I), although of no importance in this achiral molecule, the Flack absolute structure factor (Parsons et al., 2013) was determined as 0.05 (3) for 1450 Friedel pairs.

Special details
Geometry. All e.s.d.'s 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.