Synthesis of One- and Two-Dimensional Coordination Polymers Containing Organotin Macrocycles. Reactions of (<i>n</i>-Bu₃Sn)₂O with Pyridine Dicarboxylic Acids. Structure-Directing Role of the Ancillary 4,4′-Bipyridine Ligand

The reaction of (<i>n</i>-Bu₃Sn)₂O with pyridine-2,6-dicarboxylic acid (<b>L1H</b>_<b>2</b>) in a 1:1 ratio resulted in the formation of a one-dimensional (1D) coordination polymer [(<i>n</i>-Bu₃Sn)₂(<i>n</i>-Bu₂Sn)₂(μ-L1)₂(μ-OH)₂]_<i>n</i> (<b>1</b>). The formation of <b>1</b> is accompanied by a <i>Sn</i>–<i>butyl</i> bond cleavage reaction involving half of the organotin units. The formation of the 1D coordination polymer is facilitated by the multisite coordination capability of the dianionic ligand L1. The reaction of (<i>n</i>-Bu₃Sn)₂O with pyridine-2,5-dicarboxylic acid (<b>L2H</b>_<b>2</b>) or pyridine-3,5-dicarboxylic acid (<b>L3H</b>_<b>2</b>), on the other hand, results in the generation of the two-dimensional (2D) coordination polymers [(<i>n</i>-Bu₃Sn)₂(μ-L2)]_<i>n</i> (<b>2</b>) and [(<i>n</i>-Bu₃Sn)₄(μ-L3)₂]_<i>n</i> (<b>3</b>), respectively. The formation of <b>2</b> and <b>3</b> emphasizes the importance of the relative orientation of the coordinating units in the multisite coordination ligand. Compounds <b>1</b>–<b>3</b> show a rich supramolecular architecture in their solid state as a result of multiple secondary interactions. Investigation of the fate of the reactions of (<i>n</i>-Bu₃Sn)₂O with pyridine dicarboxylic acids in the presence of a bridging ligand was carried out. In all the cases when the reactions were carried out in the presence of 4,4′-bipyridine (4,4′-bipy), 1D coordination polymers [(<i>n</i>-Bu₃Sn)₂(μ-L1)­(μ-4,4′-bipy)]_<i>n</i> (<b>4</b>), [(<i>n</i>-Bu₃Sn)₂(μ-L3)­(μ-4,4′-bipy)]_<i>n</i> (<b>5</b>), and [(<i>n</i>-Bu₃Sn)₂(μ-L2)­(μ-4,4′-bipy)]_<i>n</i> (<b>6</b>) are formed. In these cases, the 4,4′-bipyridine ligand serves as one of the connectors that link the organotin units. Interestingly, in the presence of 4,4′-bipyridine, <i>Sn</i>–<i>butyl</i> bond cleavage does not take place. While the 1D coordination polymers <b>4</b> and <b>5</b> form three-dimensional supramolecular architectures in their solid state, compound <b>6</b> possesses a 2D supramolecular architecture