Crystal structures of two polymeric bis(triphenyltin) malonates

In an attempt to prepare potassium/sodium salts of malonato-triphenylstannate, two bis(triphenyltin) malonates were obtained instead, [(C₆H₅)₃Sn]₃[O₂CCH₂CO₂]_1.5 (1) and {[(C₆H₅)₃SnO₂CCH₂CO₂Sn(C₆H₅)₃]H₂O}CH₃CH₂OH (2). This provides an excellent example of structural diversity in triorganotin carboxylates. In both complexes, the dicarboxylate was connected to the triphenyltin groups forming a linear infinite polymeric chain. Both complexes have a trans-trigonal bipyramidal geometry with the three phenyl groups occupying the equatorial plane and two oxygens at axial positions. Both short and long tin–oxygen distances were observed in 1 and 2. In 1, all carboxylates functioned as bridging bidentate ligands, resulting in an infinite 3-D polymer network propagating along all three axes. In 2, Sn1 is bonded to a carboxylate and a water molecule (Sn1–O1 2.145(3)?Å, Sn1–O3 2.341(3)?Å, O1–Sn1–O3 173.97(12)°). Only one carboxylate acts as a bidentate ligand allowing the carbonyl group to be axially coordinated to the adjacent tin, Sn2. Also, Sn2 is covalently bonded to the other carboxylate group in the malonate ligand (Sn2–O4 2.163(3)?Å, Sn2–O5 2.353(3)?Å, O4–Sn2–O5 173.47(12)°). There is a water molecule included in the crystal lattice hydrogen bonded to the uncoordinated carbonyl in malonate.