Characterization of complexes formed between [Me2Sn(IV)]2+ and carboxymethylcelluloses

Area of Science:

• Materials Science
• Coordination Chemistry
• Polymer Science

Background:

• Carboxymethylcellulose (CMC) is a versatile polysaccharide with tunable properties.
• Organotin(IV) compounds exhibit diverse applications, necessitating structural understanding.
• Characterizing metal-ligand interactions in polymeric systems is crucial for material design.

Purpose of the Study:

• To synthesize and characterize solid-state complexes of carboxymethylcellulose (CMC) and dimethyltin(IV) ([Me(2)Sn(IV)]2+).
• To investigate the influence of pH on the coordination modes and structural geometry of these complexes.
• To elucidate the role of CMC's functional groups in binding with organotin(IV) cations.

Main Methods:

• Preparation of CMC-[Me(2)Sn(IV)]2+ complexes under varying conditions (pH, metal-to-ligand ratio).
• Characterization using Fourier-transform infrared (FTIR) spectroscopy to identify functional group coordination.
• Mössbauer spectroscopy to determine the oxidation state of tin and infer complex geometry.

Main Results:

• FTIR spectra indicated monodentate coordination of carboxylate groups at low pH and involvement of both carboxylate and hydroxyl groups at neutral pH.
• Mössbauer spectroscopy confirmed the Sn(IV) oxidation state in all complexes.
• Analysis of quadrupole splitting values suggested trigonal bipyramidal and octahedral geometries.

Conclusions:

• The pH of the solution is the primary factor determining the structure of CMC-[Me(2)Sn(IV)]2+ complexes.
• Complex structure is largely independent of CMC molar mass, degree of carboxylation, or metal-to-ligand ratio.
• The study provides insights into the coordination chemistry of polysaccharides with organometallic cations.