(2,2′-Bipyridine-κ2 N,N′)bis(N-isopropyl-N-methyldithiocarbamato-κ2 S,S′)cadmium

The CdII atom in the title compound, [Cd(C5H10NS2)2(C10H8N2)], exists in an N2S4 donor set defined by two chelating dithiocarbamate anions as well as a 2,2′-bipyridine ligand. The coordination geometry approximates a trigonal prism. The crystal packing features weak C—H⋯S interactions, leading to linear supramolecular chains along the a axis. The primary connections between these are by π–π stacking interactions [ring centroid distance between centrosymmetrically related pyridyl rings = 3.7455 (10) Å]. Overall, the crystal structure may be described as comprising double layers of molecules that stack along the b axis.


Comment
In continuation of systematic structural studies of various pyridyl adducts of cadmium dithiocarbamates (Song & Tiekink, 2009;Broker & Tiekink, 2011;Jamaluddin et al., 2011), the title compound Cd[S 2 CN(Me)iPr) 2 ] 2 (2,2'-bipyridine), (I), was investigated. The Cd II atom is coordinated by two dithiocarbamate ligands, each essentially forming symmetric Cd-S bonds, and a symmetrically chelating 2,2'-bipyridine ligand, Fig. 1 and Table 1. The equivalence in the Cd-S bond distances is reflected in the narrow range of associated C≐S bond distances, i.e. 1.7168 (18) to 1.7290 (17) Å. A small twist is noted between the pyridyl rings of the 2,2'-bipyridine ligand as seen in the dihedral angle of 9.25 (9) ° formed between the rings.
The N 2 S 4 donor set defines a distorted trigonal prismatic geometry.
The crystal packing of (I) features linear supramolecular chains along the a axis that are sustained by C-H···S interactions, Fig. 2 and Table 2. Chains lie in the ac plane and inter-digitate via π-π interactions with centrosymmetrically related layers to form a double layer [ring centroid(N3-pyridyl)···ring centroid(N3-centroid) i = 3.7455 (10) Å for i: 2 -x, 1 -y, 1 -z]. Double layers stack along the b axis and are separated by hydrophobic interactions, Fig. 3.

Experimental
The title compound was prepared using an in situ method by the addition of carbon disulfide (0.02 mol) to an ethanolic solution (20 ml) of methylisopropropylamine (0.02 mol) and 2,2-bipyridine (0.01 mol) in ethanol (20 ml). The mixture was

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H 0.95 to 1.00 Å) and were included in the refinement in the riding model approximation, with U iso (H) set to 1.2 to 1.5U equiv (C). Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.  (2,2'-Bipyridine-κ 2 N,N')bis (N-isopropyl-N-methyldithiocarbamato-κ

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 > 2σ(F 2 ) is used only for calculating Rfactors(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.