Dioxygenation of Sterically Hindered (Ethene)RhI and -IrI Complexes to (Peroxo)RhIII and (Ethene)(peroxo)IrIII Complexes

• Published in: European journal of inorganic chemistry Vol. 2002; no. 10; pp. 2671 - 2680
• Main Authors: de Bruin, Bas, Peters, Theo P. J., Wilting, Jos B. M., Thewissen, Simone, Smits, Jan M. M., Gal, Anton W.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-10-2002; WILEY‐VCH Verlag
• Subjects: Alkene ligands; Iridium; Oxidations; O−O activation; Peroxo ligands
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/1099-0682(200210)2002:10<2671::AID-EJIC2671>3.0.CO;2-8

New cationic, five‐coordinate bis(ethene)iridium(I) complexes [(κ3‐Me3‐tpa)IrI(ethene)2]+ (12+) and [(κ3‐Me2‐dpa‐Me)IrI(ethene)2]+ (13+) have been prepared {Me3‐tpa = N,N,N‐tris[(6‐methyl‐2‐pyridyl)methyl]amine, Me2‐dpa‐Me = N‐methyl‐N,N‐bis[(6‐methyl‐2‐pyridyl)methyl]amine}. Complexes 12+ and 13+ lose one ethene fragment in solution, yielding the five‐coordinate mono(ethene) complex [(κ4‐Me3‐tpa)IrI(ethene)]+ (14+) and the four‐coordinate mono(ethene) complex [(κ3‐Me2‐dpa‐Me)IrI(ethene)]+ (15+), respectively. [(κ4‐Me3‐tpa)RhI(ethene)]+ (11+), the rhodium analogue of 14+, was also prepared. Whereas rhodium complex 11+ is stable in acetonitrile at room temperature, the iridium analogue 14+ converts to the cyclometallated (acetonitrile)(hydrido) complex 16+ within 72 h by dissociation of the unique 6‐methylpyridyl fragment and oxidative addition of the 6‐methylpyridyl C3−H bond. The four‐coordinate mono(ethene) complex 15+ is even less stable in solution; it converts to a mixture of compounds within 18 h. Reaction of the mono(ethene)RhI complex 11+ with O2 yields the peroxo complex 17+ by ethene displacement. In contrast, the mono(ethene)IrI complexes 14+ and 15+ bind O2 without the loss of ethene, leading to unprecedented (ethene)(peroxo)IrIII complexes 18+ and 19+. At room temperature, peroxo complex 17+ does not react with ethene and, quite remarkably, C−O bond formation does not occur in the (ethene)(peroxo) complexes 18+ and 19+. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)