Ruthenium phenolates: Synthesis, characterization and reactivities of a group of salicylaldiminato and 2-(arylazo)phenolato complexes of ruthenium

Unprecedented Migration of a Methyl Group in 2-(2‘,6‘-Dimethylphenylazo)-4-methylphenol Mediated by Ruthenium

“…The present work has emerged from our interest in the C−H and C−C activation of 2-(arylazo)phenols ( 1 ) and related ligands . While ligand 1 has been observed to undergo C−H activation at one ortho position of the phenyl ring in the arylazo fragment leading to the formation of cyclometalated species ( 2 ), 1a,c-k, we have recently observed that a modified 2-(arylazo)phenol, viz.…”

“…The present work has emerged from our interest in the C−H and C−C activation of 2-(arylazo)phenols ( 1 ) and related ligands . While ligand 1 has been observed to undergo C−H activation at one ortho position of the phenyl ring in the arylazo fragment leading to the formation of cyclometalated species ( 2 ), 1a,c-k, we have recently observed that a modified 2-(arylazo)phenol, viz. 2-(2‘,6‘-dimethylphenylazo)-4-methylphenol ( 3 ), in which both the ortho positions of the phenyl ring in the arylazo fragment are strategically blocked by methyl groups, displays interestingly different reactivity 1b…”

“…Upon its reaction with [Ru(PPh 3 ) 3 Cl 2 ], or its osmium analogue, ligand 3 has been observed to undergo an unusual chemical transformation, whereby one methyl group from the phenyl ring of the arylazo fragment migrates to the metal center via oxidation to CO ( 4 ). Susceptibility of the metal center toward oxidation to the +3 state was speculated to play the key role in the observed oxidative migration of the methyl group 1b. This has encouraged us to explore the reactivity of ligand 3 with other platinum metal complexes where the metal center is not so easily oxidizable, and thus, [Ru(PPh 3 ) 2 (CO) 2 Cl 2 ] has been selected as the ruthenium complex in the present study.…”