(N-sec-Butyl-N-n-propyldithiocarbamato-κ2 S,S′)triphenyltin(IV)

The Sn atom in the title compound, [Sn(C6H5)3(C8H16NS2)], is pentacoordinated by two S atoms, derived from an asymmetrically coordinating dithiocarbamate ligand, and three ipso-C atoms. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal, with a leaning towards the latter. The presence of close intramolecular C—H⋯S contacts preclude the S atoms from forming significant intermolecular interactions. Rather, molecules are consolidated in the crystal structure by C—H⋯π interactions.

The Sn atom in the title compound, [Sn(C 6 H 5 ) 3 (C 8 H 16 NS 2 )], is pentacoordinated by two S atoms, derived from an asymmetrically coordinating dithiocarbamate ligand, and three ipso-C atoms. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal, with a leaning towards the latter. The presence of close intramolecular C-HÁ Á ÁS contacts preclude the S atoms from forming significant intermolecular interactions. Rather, molecules are consolidated in the crystal structure by C-HÁ Á Á interactions.

Related literature
For a review of the applications and structural chemistry of tin dithiocarbamates, see: Tiekink (2008). For a related organotin structure having the same dithiocarbamate ligand, see: Abdul Muthalib et al. (2010). For additional structural analysis, see: Addison et al. (1984).

Comment
Organotin dithiocarbamates display properties that suggest their use as anti-cancer agents, anti-microbial agents and as insecticides (Tiekink, 2008). Such interest motivates on-going structural characterization of such compounds (Abdul Muthalib et al., 2010) and led to the investigation of the title compound, (I).
The Sn atom in (I) is penta-coordinated by two S atoms derived from an asymmetrically coordinating dithiocarbamate ligand and three ipso-C atoms from the phenyl substituents, Fig. 1. The resulting C 3 S 2 coordination geometry is intermediate between square pyramidal and trigonal bi-pyramidal with a leaning towards the latter. Thus, compared to the ideal values for τ of 0.0 and 1.0 for ideal square pyramidal and trigonal bi-pyramidal geometries, respectively (Addison et al., 1984), the value for τ in (I) computes to 0.55. The asymmetric mode of coordination of the dithiocarbamate ligand is reflected in significant differences in the associated C-S bond distances with that formed by the S1 atom, involved in the shorter of the Sn-S bonds, being considerably longer [S1-C19 = 1.755 (3) Å] than that formed by the S2 atom [S2-C19 = 1.682 (3) Å].
The observed molecular structure is entirely consistent with literature precedents (Tiekink, 2008).
Each of the S atoms is involved in two intramolecular C-H···S contacts and these do not participate in intermolecular interactions, Table 2. The presence of C-H···π contacts are noted, Table 1, and occur between benzene-and methyl-H atoms with two of the Sn-bound benzene rings functioning as the acceptors. These serve to consolidate the molecules into the crystal structure, Fig. 2.

Experimental
Carbon disulfide (30 mmol) was dropped into an ethanol solution (100 ml) of N-sec-butyl-N-n-propylamine (30 mmol). The solution was kept at 273 K for an hour. Triphenyltin chloride (30 mmol) dissolved in ethanol (100 ml) was added to give a white precipitate. This was collected and colourless crystals were obtained by recrystallization from its chloroform/ethanol (1/1) mixture.

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H 0.93 to 0.98 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 the atom-labelling scheme and displacement ellipsoids at the 50% probability level.