Structure and Bonding in Nickel-Thiolate-Iodine Charge-Transfer Complexes

Area of Science:

• Coordination Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Dinuclear nickel complexes with macrocyclic ligands are known for their diverse reactivity.
• Charge-transfer (CT) complexes involve the transfer of electron density between donor and acceptor molecules.
• Polyiodide structures are often observed in complexes with electron-rich ligands.

Purpose of the Study:

• To synthesize and characterize novel charge-transfer adducts of dinuclear nickel complexes with iodine.
• To investigate the structural features and bonding characteristics of these CT adducts.
• To explore the stability and potential applications of these novel compounds.

Main Methods:

• Synthesis of dinuclear nickel complexes with a macrocyclic N6S2 ligand.
• Reaction of nickel complexes with excess iodine (I2) to form CT adducts.
• Characterization using X-ray crystallography, spectroscopy, and Density Functional Theory (DFT) calculations.

Main Results:

• Formation of stable mono- and bis-(I2) charge-transfer adducts with the general formula [Ni2L(μ-O2CR)(I2)n]+ (n=1 or 2).
• Isolation and characterization of three new CT compounds and one triiodide salt.
• Observation of a polyiodide matrix stabilized by secondary I···I interactions, with variable RS-I and I-I bond lengths indicating varying charge transfer.

Conclusions:

• The study successfully synthesized and characterized novel dinuclear nickel-iodine charge-transfer complexes.
• Structural analysis and DFT calculations provided insights into the bonding and charge transfer mechanisms.
• The stability and preliminary transport measurements suggest potential for these complexes in materials science applications.