Poly[[aqua-μ(3)-2,2-dimethylmalonato-copper(II)] monohydrate] and poly[aqua-μ(3)-2,2-dimethylmalonato-copper(II)]

Area of Science:

• Coordination Chemistry
• Materials Science
• Crystallography

Background:

• Dimethylmalonate is a versatile ligand in coordination chemistry.
• Copper(II) complexes are of interest due to their diverse applications.
• Metal-organic frameworks (MOFs) offer tunable properties for various uses.

Purpose of the Study:

• To synthesize and characterize two novel copper(II) complexes with dimethylmalonate.
• To investigate the coordination modes and structural differences of the complexes.
• To analyze the resulting metal-organic framework connectivity and hydrogen bonding.

Main Methods:

• Single-crystal X-ray diffraction to determine molecular and crystal structures.
• Infrared spectroscopy to confirm ligand coordination.
• Powder X-ray diffraction for phase purity analysis.

Main Results:

• Both complexes feature dimethylmalonate ligands with identical coordination modes (chelated, bis-monodentate, bridging).
• Complex (I) displays a square-pyramidal Cu(II) environment and a single type of square grid in its 2D layers.
• Complex (II) shows a distorted square-pyramidal Cu(II) geometry and two alternating grid types within its 2D layers, with stronger intra-layer hydrogen bonding.

Conclusions:

• The coordination mode of dimethylmalonate is conserved, but structural variations arise from Cu(II) coordination environments and framework connectivity.
• Differences in framework assembly and hydrogen bonding lead to distinct structural motifs in the two copper(II) complexes.
• These findings highlight the subtle control over MOF architecture through ligand and metal coordination.