623566-72-3Relevant academic research and scientific papers
Unsymmetrically bridging aryls of iridium
Muldoon, John,Brown, Seth N.
, p. 4480 - 4489 (2003)
The iridium(I) complex [(cod)IrCl]2 (1; cod = 1,5-cyclooctadiene) reacts with 2,6-disubstituted aryl Grignard reagents to give air-stable diiridium complexes (cod)IrBr(μ,k1:η6-Ar)Ir-(cod) (Ar = 2,4,6-Me3C6H2 (2), 2,6-Me2C6H3 (3)). The aryl groups in these compounds are σ-bonded to one square-planar iridium(I) center and π-bonded to another (cyclooctadiene)- iridium(I) fragment. Spectroscopic and structural data indicate that the bonding is best described as a resonance hybrid between a zwitterionic σ-aryl/η6-arene structure and a neutral carbene/η5-cyclohexadienyl structure, with the former making a greater contribution. The resonance appears to stabilize both the iridium(I)-aryl σ- and π-bonds, with the result that the bridging aryl moiety is extremely chemically robust. The complexes react selectively at the square-planar iridium, undergoing ligand substitution of the cyclooctadiene or halide and oxidative addition of I2.
