# The influence of the substituent type and position on the topology of 2-D heterometallic sodium–palladium(ii) coordination networks with substituted nicotinate ligands

## TL;DR

This paper shows how different chemical groups on a molecule can change the shape of a metal-based network structure.

## Contribution

The study reveals how substituent position and type influence the topology of heterometallic coordination networks.

## Key findings

- 2-methylnicotinate and 6-fluoronicotinate ligands lead to distinct 2-D network topologies.
- Electronic and steric effects of substituents influence intermolecular interactions and hydrogen-bond motifs.
- The trans-configuration of Pd(II) ions is preserved in both networks.

## Abstract

Two 2-D heterometallic sodium–palladium(ii) coordination networks with 2-methylnicotinate (2-methylpyridine-3-carboxylate, 2-Menic) and 6-fluoronicotinate (6-fluoropyridine-3-carboxylate, 6-Fnic) ligands, {[Na2(H2O)2(µ-H2O)4PdCl2(µ-2-Menic-N:O′)2]·2H2O}n (1) and {[Na2(H2O)2(µ-H2O)4PdCl2(µ-6-Fnic-N:O′)2]·2H2O}n (2), respectively, were prepared in aqueous solutions (1) or ethanol/water mixtures (2) in the presence of NaHCO3. Both compounds form 2-D polymeric layers composed of water-bridged sodium ion chains linked by [PdCl2(2-Menic)2]2− moieties in 1 or by [PdCl2(6-Fnic)2]2− moieties in 2, which exclusively adopt the trans-configuration around the Pd(ii) ion. The different positions and electronic properties of 2-Menic and 6-Fnic ligands change the local electrostatic environment of the coordinated Pd(ii) ions and influence intermolecular interactions, including the stabilizing R22(8) hydrogen-bond motif involving C–H⋯F hydrogen bonds in 2, thereby determining the overall topology of the said 2-D heterometallic sodium–palladium(ii) coordination networks.

Two 2-D heterometallic sodium–palladium(ii) coordination networks with 2-methylnicotinate and 6-fluoronicotinate ligands were prepared, showing that the substituent type and position control a linear or zigzag topology.