Bis(μ-2-{[oxido(phenyl)methylidene]hydrazinylidene}propanoato)bis[dibenzyl(ethanol)tin(IV)]

In the title complex, [Sn2(C7H7)4(C10H8N2O3)2(C2H5OH)2], the Sn(IV) atom is seven-coordinated in a distorted pentagonal–bipyramidal geometry by three O atoms and one N atom from the pyruvate benzoyl hydrazone ligand, one ethanol O atom and two axial C atoms from trans-benzyl groups, thus forming a dimeric molecule ( symmetry) via weak Sn—O interactions. The C atoms of one phenyl ring and the ethanol molecule are disordered over two sets of sites with site-occupancy factors of 0.57 (5):0.43 (5) and 0.79 (2):0.21 (2), respectively. Intermolecular O—H⋯O hydrogen bonds stabilize the crystal structure.


Bis(µ-2-{[oxido(phenyl)methylidene]hydrazinylidene}propanoato)bis[dibenzyl-(ethanol)tin(IV)]
Shaojun Sun and Jie Yang S1. Comment Organotin derivatives of carboxylic acid ligands have been extensively studied due to their biological activities (Gielen et al., 2002). In our ongoing studies with Schiff base organotin(IV) compounds, the title compound has been synthesized and we report herein its crystal structure. The molecular structure of the compound is shown in Fig.1. The atoms O1, O3, N1 and O4 are coplanar within 0.0120 Å, which form the equatorial plane. Furthermore, the angle of the axial C11-Sn1 -C18 is 163.3 (3)°, which deviates from the linear angle of 180°. These data indicate that the tin atom of this complex is in a distorted octahedral configuration. The O1 atom of the carboxylate residue also binds the other tin atom, Sn i , generating a Sn 2 O 2 four-membered ring [symmetry code: 2 -x, 2 -y, -z]. The distances of Sn1-O1 i 2.772 (4)Å are relatively longer than those of Sn1-O1 2.339 (4)Å (Table 1), but are comparable with those found in related sevencoordinate diorganotin systems (Sun et al., 2007). With weak interactions of Sn-O bonding, the structure of the title complex can be described as a dimer with crystallographically imposed 1 symmetry. and the coordination geometry of tin can be also described as a trans-C 2 SnO 4 N pentagonal bipyramid with the two benzyl groups occupying trans positions.
The forming of the dimer leads to the shorter interaction between O and O i , because the interaction of two monomers surpass the repelling effect of two O atoms. Otherwise, there exhibit the disorder at the C12 to C17 aromatic ring moiety and the C25, C26 atoms of the coordinated ethonal solvate molecule.
Each Sn atom is also coordinated by an ethanol molecule, the Sn1-O4 bond distance being 2.424 (3) Å, which is comparable with those in the analogous (Sun et al., 2007), due to the formation of intradimeric hydrogen bonds, O2-O4 i (or O2 i -O4) 2.624 (6)Å (Table 2). These hydrogen bonds contribute to the stability and compactness of the crystal structure ( Fig. 2).

S2. Experimental
Pyruvic acid benzoyldrazone (1 mmol) and sodium ethoxide (1 mmol) was added to the solution of dry benzene (20 ml) in a Schlenk flask and stirred for 0.5 h. Dibenzyltin dichloride (1 mmol) was then added and the reaction mixture was stirred for 12 h at 313 K and then filtered. The solvent was gradually removed by evaporation under vacuum until a solid product was obtained. The solid was then recrystallized from ethanol and colorless crystals suitable for X-ray diffraction were obtained. Elemental analysis, calculated for C 26 H 28 N 2 O 4 Sn: C 56.66, H 5.12, N 5.08; found: C 56.51, H 5.34, N 5.01%.

S3. Refinement
The atoms C12, C13, C14, C15, C16 and C17 of the phenyl ring, C25 and C26 of the ethanol molecule were found to be disordered over two sites, and the ratio of the occupancy factors were refined to 0.57 (5) -H distances of 0.93 Å, and refined as riding on their parent atoms, with U iso (H) = 1.2 U eq (C, O). All other H atoms were also placed in idealized positions, with U iso (H) = 1.5 U eq (C, O).

Figure 1
The molecular structure of the compound, showing 50% probability displacement ellipsoids. H atoms have been omitted for clarity. Symmetry code: 2 -x, 2 -y, -z.

Figure 2
The crystal packing in a unit cell of the title complex, viewed along the b axis. H atoms have been omitted.