Anion-Dependent Switch in C-X Reductive Elimination Diastereoselectivity

Area of Science:

• Organometallic Chemistry
• Reaction Mechanisms
• Stereochemistry

Background:

• Reductive elimination is a key step in organometallic catalysis.
• Understanding reaction mechanisms is crucial for catalyst design.
• Stereochemical outcomes provide insights into reaction pathways.

Purpose of the Study:

• To investigate the mechanism of reductive elimination in platinum organometallic complexes.
• To determine the effect of halide ligands on the reaction pathway and stereochemistry.
• To elucidate the role of five-coordinate platinum(IV) intermediates.

Main Methods:

• Reaction of platinum organometallic complexes with electrophilic halogen sources.
• Inclusion and exclusion of halide (X-) ligands.
• Analysis of stereochemical outcomes (retentive vs. inversive).

Main Results:

• In the absence of added X- ligands, reductive elimination is stereoretentive.
• In the presence of added X- ligands, reductive elimination proceeds via an SN2-type pathway, leading to stereoinversion.
• A key five-coordinate Pt(IV) intermediate dictates the selectivity based on X- ligand reactivity.

Conclusions:

• Halide ligands fundamentally alter the reductive elimination mechanism in these platinum complexes.
• The stereochemical outcome is controllable by the presence or absence of halide ligands.
• The reactivity of Pt(IV) intermediates is central to understanding this mechanistic switch.