Solvent-modulated reversible conversion of a [2 x 2]-grid into a pincer-like complex

Area of Science:

• Coordination chemistry
• Supramolecular chemistry
• Materials science

Background:

• Triazine-derived ligands are versatile building blocks in coordination chemistry.
• Solvent-mediated self-assembly is crucial for controlling the architecture of metal complexes.
• Cobalt(II) complexes exhibit diverse coordination geometries and magnetic properties.

Purpose of the Study:

• To investigate the solvent-dependent self-assembly of cobalt(II) complexes with a specific triazine ligand.
• To explore the interconversion between different structural motifs (grid vs. pincer).
• To understand the role of external factors, such as amines, in directing structural transformations.

Main Methods:

• Synthesis of cobalt(II) complexes using a triazine-derived ligand.
• Crystallization from different solvents (nitromethane and acetonitrile) to isolate distinct architectures.
• Structural characterization using X-ray diffraction.
• Investigating the reversibility of structural interconversion and the effect of amine additives.

Main Results:

• Two distinct cobalt(II) complexes were obtained: a tetranuclear grid-like structure from nitromethane and a mononuclear pincer-like structure from acetonitrile.
• The grid and pincer complexes can be reversibly interconverted.
• The addition of amines significantly accelerates the conversion from the grid to the pincer complex.

Conclusions:

• The choice of crystallization solvent dictates the self-assembly pathway and final architecture of cobalt(II)-triazine complexes.
• The observed structural interconversion highlights the dynamic nature of these coordination compounds.
• Amine additives can act as catalysts or directing agents to control supramolecular transformations.