Coordination polymers constructed from triorganotin(IV) nodes and fumarato spacers

Two novel coordination polymers have been constructed from triorganotin nodes, {R3Sn}, and fumarato (fum2-) spacers: 2∞[(Me3Sn)2(fum)] 1 and 3∞[(nBu3Sn)2(fum)] 2. In both compounds the fumarato ion acts as a tetradentate ligand and the tin atoms are 5-coordinate with a trigonal bipyramidal geometry, with the apical positions occupied by oxygen atoms from the fum2- ligands. The crystal structure of 1 consists of infinite parquet-like layers (2-D), formed by coordination driven self-assembly. Compound 2 is a 3-D self-assembled polymer, whose architecture results by fusing two types of metallacycles, each one containing six tin atoms. The multinuclear NMR spectra of the solutions obtained by dissolving compounds 1 and 2 in CDCl3 and DMSO-d6 indicate that the polymeric structures are not preserved.