Aminoethyl‐Functionalized Cyclopentadienyliridium Complexes: Photochemical C–H Activation and Carbonylation of Cycloalkanes

Abstract

The photochemical C–H activation of cycloalkanes by aminoethyl‐functionalized cyclopentadienyliridium complexes proceeds in a broadly similar way to that for their unfunctionalized analogues. In a carbon monoxide atmosphere, there is evidence that carbonylation to form the carboxaldehyde occurred with both systems. In situ infrared spectroscopic studies on these reactions allow the identification of several species present in low concentrations in the reaction mixture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Reaction of [M(CO)4]− (M=Ir, Rh) with cyclopropenyl tetrafluoroborate – Ring opening and coupling of cyclopropenyl ligands to form dinuclear metal complexes

“…g 3 ring-slippage in a similar fashion to its acylic g 3 -propenyl (allyl) analogue [1]. Our interest in this class of compound was prompted by our earlier finding that the photolysis of a cyclohexane solution of Cp * Ir(CO) 2 under a CO atmosphere produced small amounts of cyclohexanecarboxaldehyde [2]. We surmised that the low yield may be related to the fact that migratory insertion of CO is less favourable for Ir than for Rh, but this may be encouraged by steric effects [3].…”

Photolytic C–H activation and dehydrogenation of alkanes at cyclopentadienyl iridium complexes in a perfluorinated solvent

“…4 The iridium(I) complex [{(η 5 -C 5 H 4 -(CH 2 CH 2 NMe 2 ))}Ir(CO) 2 ], which bears a remote amino group with hemilabile coordinating properties, is also capable of dehydrogenation of cyclohexane to give cyclohexene and H 2 under photolytic conditions at room temperature. 5 The oxidative addition of a C-H bond at a cyclopentadienyl iridium(I) intermediate species can be considered as a key step in such a process. Note that a C-H activation of cyclohexane on using [(Cp)Ir(CO) 2 )] (1) (Cp = C 5 H 5 ) as a source of {(Cp)Ir(CO)} was already described in the early eighties, but a dehydrogenation of the alkane was not reported.…”