Potassium morpholine-4-carbodithioate monohydrate

In the ionic title compound, K+·C5H8NOS2 −·H2O, the morpholine ring of the morpholine-4-carbodithioate anion has a chair conformation. The potassium cation is coordinated by four S and four O atoms in a bipyramidal reversed geometry. In the crystal, the three components are linked, generating infinite two-dimensional networks that lie parallel to the bc plane. These layers are linked via O—H⋯S hydrogen bonds, forming a three-dimensional structure.


Comment
The title compound, Fig. 1, is composed of a morpholinedithiocarbamate anion in contact with a potassium cation, which in turn is linked with a water molecule of crystallization. The crystal structure of similar compounds, for example Sodium 1-R-carbodithioate dihydrate, have been reported (Oskarsson et al., 1979;Albertsson et al., 1980;Ymén, 1982;Mafud & Gambardella et al., 2011a,b).
The six-membered morpholine ring has a chair conformation with Puckering parameters [Cremer & Pople, 1975) In the crystal, a polymeric structure is built by coordination of the potassium cation to four sulfur [K···S = 3.2670 (13) -3.3797 (14) Å] and four oxygen [K···O = 2.828 (3) -3.007 (3) Å] atoms, with a bi-pyramidal reversed geometry. This configuration generates close packed layers which remain cohesive in crystal stacking by van der Waals interactions. The distances of these contacts are slightly less than the sum of the van der Waals radii.
The crystal packing gives rise to a supramolecular structure, whose infinite two-dimensional network lies parallel to the bc plane (Fig. 2). These layers are linked via O-H···S hydrogen bonds (Table 1) to form a three-dimensional structure.

Experimental
The potassium salts of DTC were prepared by direct reaction between amine and carbon disulfide (CS 2 ) in the presence of a stoichiometric amount of potassium hydroxide in ethanol/water 1:1 (v:v). The reaction mixture was placed in the freezer for 12 h and then filtered through a Büchner funnel, washed with cold ether and the product recrystallized in an ethanol-water mixture 1:1 (v:v). The obtained solid was recrystallized from ethanol-water 1:1 (v/v) and dried in a vacuum oven at 323 K for 8 h. Colourless crystals, suitable for X-ray diffraction analysis, were obtained. On heating they sublimed and decomposed.

Refinement
The H-atom positions of the water molecule were located in a difference Fourier map and were refined with U iso (H) =  A view of the molecular structure of the asymmetric unit of the title compound, with the numbering scheme. The displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The view along the c axis of the crystal packing of the title compound.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles 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.