Bis(5-methylpyrazine-2-carboxylato)diphenyltin(IV)

In the molecule of the title compound, [Sn(C6H5)2(C6H5N2O2)2], two O and one N atoms from the two 5-methylpyrazine-2-carboxylate ligands and one C atom of a phenyl group form a distorted square-planar arrangement in the equatorial plane around the Sn atom, while the distorted octahedral coordination is completed by an N atom of one of the 5-methylpyrazine-2-carboxylate ligands and a C atom of the other phenyl group in the axial positions. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers.

In the molecule of the title compound, [Sn(C 6 H 5 ) 2 -(C 6 H 5 N 2 O 2 ) 2 ], two O and one N atoms from the two 5methylpyrazine-2-carboxylate ligands and one C atom of a phenyl group form a distorted square-planar arrangement in the equatorial plane around the Sn atom, while the distorted octahedral coordination is completed by an N atom of one of the 5-methylpyrazine-2-carboxylate ligands and a C atom of the other phenyl group in the axial positions. In the crystal structure, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into centrosymmetric dimers.
The molecule of the title compound, (I), (Fig. 1) consists of two phenyl and two (5-methylpyrazine-2-carboxylate) groups bonded to the Sn atom and has a monomeric structure. The two O and the one N atoms of the two 2-methylpyrazine -5-carboxylate ligands and the one C atom of the one phenyl group in the equatorial plane around the Sn atom form a distorted square-planar arrangement, while the distorted octahedral coordination is completed by the one N atom of the one 5-methylpyrazine-2-carboxylate ligand and the one C atom of the other phenyl group in the axial positions (Table 1 and  In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 2) link the molecules into centrosymmetric dimers ( Fig. 2), in which they may be effective in the stabilization of the structure.

S2. Experimental
For the preparation of the title compound, a mixture of diphenyltin dichloride (344 mg, 1.0 mmol), 5-methylpyrazine-2carboxylic acid (276 mg, 2.0 mmol) and sodium ethoxide (136 mg, 2.0 mmol) in ethanol (80 ml) was heated under reflux for 12 h at 303 K. The resulting clear solution was evaporated under vacuum and the product recrystallized from a mixture of methanol to yield colorless, block-like crystals of (I) (yield; 377 mg, 69%, m.p. 459 K). Analysis, calculated for (I): C 52.68, H, 3.68; N 10.24%; found: C 52.96, H 3.87, N, 10.11%.  The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
A partial packing diagram of (I). Hydrogen bonds are shown as dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.56 e Å −3 Δρ min = −0.46 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) 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. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq