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High Selectivity in Csp2-Csp2 versus Csp3-O Reductive Elimination from Cycloplatinated(IV) Complexes
Marzieh Dadkhah Aseman1, Susan Kiyavash1
1Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box, Tehran 14115-175, Iran.
Inorganic Chemistry
|June 22, 2024
Summary
New cycloplatinated(IV) complexes undergo distinct reductive elimination pathways. Unlike methyl complexes, aryl-heteroaryl coupling occurs via a unique three-center transition state after water ligand dissociation.
Area of Science:
- Organometallic Chemistry
- Platinum(IV) Complexes
- Reductive Elimination Mechanisms
Background:
- Cycloplatinated(IV) complexes are synthesized via oxidative addition.
- Understanding reductive elimination (RE) pathways is crucial for catalytic applications.
- Previous studies on methyl complexes showed C-O reductive elimination.
Purpose of the Study:
- To synthesize and characterize novel cycloplatinated(IV) complexes.
- To investigate the reductive elimination mechanism of these complexes.
- To compare the RE pathway with that of analogous methyl complexes.
Main Methods:
- Synthesis of trans-[Pt(aryl)(C^N)(OAc)2(H2O)] complexes.
- Thermolysis of platinum(IV) complexes.
- Density Functional Theory (DFT) calculations.
- Experimental observation of reaction products.
Main Results:
- Successful synthesis of cycloplatinated(IV) complexes 2a and 2b.
- Thermolysis of complex 2a yielded cis-[Pt(kappa(1)N-aryl-bhq)(OAc)2(H2O)] (3a) via Csp2Ar-Csp2bhq coupling.
- DFT and experimental data indicate water ligand dissociation precedes Csp2Ar-Csp2bhq coupling.
- The Csp2Ar-Csp2bhq coupling proceeds through a three-center ring transition state.
Conclusions:
- The reductive elimination pathway for aryl-heteroaryl coupling in platinum(IV) complexes differs significantly from methyl complexes.
- Water ligand dissociation is a key step initiating the Csp2Ar-Csp2bhq coupling.
- A three-center ring transition state governs the Csp2Ar-Csp2bhq reductive elimination.
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