Novel linear hexanuclear cobalt string complexes (Co6(12+)) and one-electron reduction products (Co6(11+)) supported...

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• The synthesis of novel ligands is crucial for developing new metal complexes.
• Hexacobalt clusters offer unique structural and electronic properties.

Purpose of the Study:

• To synthesize a new ligand, 2,7-bis(alpha-pyridylamino)-1,8-naphthyridine (H2bpyany).
• To prepare and characterize novel hexacobalt string complexes using the synthesized ligand.
• To investigate the structural, electronic, and magnetic properties of these complexes.

Main Methods:

• Ligand synthesis via palladium-catalyzed cross-coupling.
• Preparation of hexacobalt complexes with NCS and OTf counterions.
• X-ray crystallography for structural determination.
• Electrochemical analysis (cyclic voltammetry).
• Magnetic susceptibility measurements.
• Extended Hückel Molecular Orbital (EHMO) calculations.

Main Results:

• Successful synthesis of H2bpyany ligand.
• Formation of four hexacobalt string complexes: [Co6(bpyany)4(NCS)2](PF6)n (n=1, 2) and [Co6(bpyany)4(OTf)2](OTf)n (n=1, 2).
• Compounds 1 and 4 (Co6 11+) are air-stable with S=1/2 spin states.
• Compounds 2 and 3 (Co6 12+) exhibit S=1 spin states.
• Electrochemical studies revealed four redox couples for compound 1.
• EHMO calculations corroborated magnetic data.

Conclusions:

• The new H2bpyany ligand facilitates the formation of novel hexacobalt string complexes.
• The complexes display tunable electronic configurations and magnetic behaviors based on cobalt oxidation states.
• Structural and computational data provide insights into the electronic structure and magnetic properties of these multinuclear cobalt systems.