Dihydrogen binding to isostructural S = ½ and S = 0 cobalt complexes

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Coordination Chemistry

Background:

• Cobalt complexes are crucial in catalysis and materials science.
• Understanding ligand binding and lability is key to designing functional metal complexes.
• Nonclassical H(2) and N(2) complexes offer unique reactivity pathways.

Purpose of the Study:

• To synthesize and characterize novel isostructural cobalt complexes with H(2) and N(2) ligands.
• To investigate the ligand binding equilibria and energetics of these complexes.
• To compare the properties of complexes with tris(phosphino)silyl and tris(phosphino)borane ancillary ligands.

Main Methods:

• Synthesis of cobalt complexes via comproportionation and reduction reactions.
• Characterization using X-ray crystallography and various spectroscopic techniques (UV/Vis, NMR).
• Determination of ligand binding energetics using temperature-dependent UV/Vis spectroscopy and van't Hoff analysis.

Main Results:

• Two isostructural, nonclassical Co(H(2)) and Co(N(2)) complexes were successfully prepared using tris(phosphino)silyl and tris(phosphino)borane ligands.
• Both H(2) and N(2) ligands were found to be labile under ambient conditions.
• Thermodynamic parameters (ΔH°, ΔS°) for H(2) and N(2) binding were quantified.

Conclusions:

• The synthesized cobalt complexes represent a new class of nonclassical H(2) and N(2) coordination compounds.
• The lability of H(2) and N(2) ligands is a key feature, enabling observable binding equilibria.
• The determined energetics provide insights into the stability and reactivity of these complexes, relevant for future catalytic applications.