Sulfur insertion into group 12 metal dithiolate complexes: metal-dependent equilibria.

Area of Science:

• Coordination chemistry
• Organometallic chemistry
• Inorganic chemistry

Background:

• Dianionic bis(carboxamide)pyridine-supported metal(II) dithiolate complexes offer a versatile platform for studying metal-sulfur interactions.
• Previous work established a zinc variant with a defined [N3S2] coordination geometry.

Purpose of the Study:

• To synthesize and characterize cadmium(II) and mercury(II) analogues of the zinc dithiolate complex.
• To investigate the reactivity of these complexes towards elemental sulfur (S8).
• To elucidate the factors governing sulfur insertion thermodynamics.

Main Methods:

• Synthesis of Cd(II) and Hg(II) dithiolate complexes.
• X-ray crystallography to determine coordination geometries.
• Reactions with elemental sulfur (S8) and product characterization.
• Electrochemical analysis (oxidation potentials).

Main Results:

• Cd(II) and Hg(II) complexes exhibited isostructural [N3S2] coordination but with distortions due to ionic radius differences.
• Sulfur insertion into Cd(II) and Hg(II) complexes yielded multiple products with varying equilibrium constants, unlike the selective insertion in the zinc complex.
• Reactivity correlated with metal thiolate nucleophilicity and electrochemical oxidation potentials.

Conclusions:

• Ionic radius and resulting geometric distortions significantly impact sulfur insertion pathways.
• Sulfur insertion thermodynamics are influenced by metal-specific properties, ring strain, and steric effects.
• The study highlights the complex interplay of factors controlling sulfur reactivity in metal dithiolate systems.