Spin-Orbit Coupling and Outer-Core Correlation Effects in Ir- and Pt-Catalyzed C-H Activation

Area of Science:

• Computational Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• C-H activation is a fundamental transformation in synthetic chemistry.
• Iridium and platinum are key heavy transition metals used as catalysts.
• Quantum mechanical effects like spin-orbit coupling and electron correlation can influence reaction pathways.

Purpose of the Study:

• To investigate the role of spin-orbit coupling (SOC) and outer-core (5s5p) correlation effects.
• To quantify these effects on C-H activation barriers in Ir- and Pt-catalyzed systems.
• To understand trends in these effects based on oxidation state and coordination.

Main Methods:

• High-level ab initio computations were employed.
• The study focused on Ir(I), Ir(III), Pt(0), and Pt(II) complexes.
• Analysis of C-H activation barriers was performed.

Main Results:

• SOC and outer-core correlation effects on C-H activation are approximately 1 kcal/mol for these heavy metals.
• SOC effects consistently increase C-H activation barriers, with larger effects in higher oxidation states.
• Outer-core correlation effects are more significant in less coordinate-saturated systems.
• Basis set size impacts outer-core correlation corrections, with larger basis sets increasing barriers.

Conclusions:

• Spin-orbit coupling and outer-core correlation are essential for accurate theoretical predictions of C-H activation by Ir and Pt.
• These effects exhibit distinct trends related to the electronic structure of the metal centers.
• Computational methodology, including basis set choice, must carefully consider these quantum mechanical phenomena.