Synthesis of a chloro protected iridium nitrido complex

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry

Background:

• Late transition metal complexes with terminal metal nitrido units often suffer from limited thermal stability due to intramolecular C-H bond activation.
• This instability restricts their accessibility and synthetic utility.

Purpose of the Study:

• To enhance the thermal stability and accessibility of square-planar iridium nitrido compounds.
• To investigate the effect of chloro substitution on the N-aryl substituents of pyridine, diimine ligands.

Main Methods:

• Thermoanalytical methods including thermogravimetric derivative/mass spectrometry (DTG/MS) and differential scanning calorimetry (DSC).
• Density functional theory (DFT) calculations to elucidate decomposition pathways and mechanisms.
• Characterization of the isolated nitrido complex using UV/vis, IR spectroscopy, and elemental analysis.

Main Results:

• Chloro substitution (R = Cl) on N-aryl groups leads to two distinct, well-separated exothermic decomposition steps in iridium azido precursors.
• This contrasts with dimethyl (R = Me) substituted analogues where decomposition occurs concurrently.
• The controlled decomposition enabled the isolation and characterization of the highly insoluble iridium nitrido complex.

Conclusions:

• Chloro substitution effectively increases the thermal stability of iridium nitrido compounds.
• The distinct decomposition pathways provide mechanistic insights and facilitate the isolation of target complexes.
• The synthesized nitrido complex was confirmed through spectroscopic methods and reaction with silanes.