An Easy Conversion from Platinum(II) Reagents to Platinum(IV) Products: kappa(3) to kappa(2) Coordination Mode Interconversion, Phenyl Migration, and Ortho C-H Activation Cascade in a Hemilabile "Click"-Triazole Scorpionate Platinum System

作者：Frauhiger Bryan E; Templeton Joseph L^*

来源：Organometallics, 2012, 31(7): 2770-2784.

DOI：10.1021/om2010595

A series of platinum phenyl olefin complexes has been prepared that bear hemilabile "Click"-triazole based scorpionate ligands (Tt(R)). Mild heating of the olefin adducts initiates a reaction sequence to form stable, cationic Pt(IV) hydride metallacycles. An attractive mechanism involves kappa(3)/kappa(2) conversion, phenyl migration, and ortho C-H activation. Activation parameters for the overall C-C bond-forming and C-H bond-breaking process were obtained. Insertion products from mono- and disubstituted olefins reveal a kinetic preference for phenyl migration to the less sterically hindered olefin position but a thermodynamic preference for the beta-substituted metallacycle isomer, in which steric bulk is further away from the metal center and the Tt(R) ligand. Thermolysis converts the kinetically favored products to their thermodynamically stable isomers via a reversible C-C bond cleavage and formation reaction. EXSY NMR and deuterium-labeling studies reveal facile scrambling processes in the metallacycles due to the hemilabile ligand.

• 出版日期2012-4-9