Poly[[aquadi-μ3-malonato-hexaphenylditin(IV)] acetone solvate]

The asymmetric unit of the title polymeric complex, {[Sn2=(C6H5)6(C3H2O4)(H2O)]·C3H6O}n, comprises of two Sn cations, one malonate anion and a non-coordinating acetone solvent molecule. Both crystallographically independent Sn cations are five-coordinated by two O and three C atoms in a distorted trigonal-bipyrimidal geometry. One of the Sn cations is bridged by the malonate units, affording polymeric chains which run along [001]. Weak intramolecular C—H⋯π interactions stabilize the molecular structure. In the crystal structure, adjacent chains are interconnected by intermolecular O—H⋯O and C—H⋯O hydrogen bonds into a three-dimensional supramolecular structure. A weak intermolecular C—H⋯π interaction is also observed.


metal-organic compounds
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 The asymmetric unit of the title polymeric complex comprises of two crystallographically independent Sn cations (Sn1 and Sn2) and a non-coordinating acetone solvent molecule (Fig. 1). Both Sn cations are five-coordinated by two O and three C atoms. The coordination geometries are distorted from the ideal trigonal bipyrimidal geometry, resulting in see-saw shaped geometries. The coordination environments are different for the two Sn cations (Fig. 2). The Sn1 cation is coordinated to three phenyl ligands and two carbonyl O atoms, forming one-dimensional polymeric chains along the [001] direction whereas the Sn2 cation is coordinated to three phenyl ligands, a water molecule and a carbonyl O atom. Further stabilization of the molecular structure is provided by the weak intramolecular C8-H8A···Cg1 and C38-H38B···Cg2 interactions ( Table 2).  Table 1. All bond lengths and angles are comparable to a closely related bis(triphenyltin) structure (Ng, 1998).

Experimental
The title complex was obtained by heating under reflux a 2:1 molar mixture of triphenyltin(IV) hydroxide (4 mmol, 1.47 g) and malonic acid (2 mmol, 0.21 g) in acetone (60 ml The water molecule H atoms were located from the difference Fourier map and constrained to ride with the parent atom with U iso = 1.5 U eq (O). All other H atoms were placed in their calculated positions, with C-H = 0.93 -0.97 Å, and refined using a riding model with U iso = 1.2 or 1.5 U eq (C). A rotating group model was used for the C40 and C42 methyl groups.
In the acetone solvent molecule, all atoms were refined isotropically and the C-O and C-C distances were fixed at 1.20 (1) and 1.50 (1) Å, respectively. EADP restraints were also imposed on C4:C8 and C37:C39 atom pairs. 4262 Friedel pairs were used in the final refinement to determine the absolute structure. The highest residual electron density peak is located at 1.25 Å from C41 and the deepest hole is located at 0.84 Å from Sn1.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
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.
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 > 2sigma(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.