An efficient methylenation reaction using triphenylphosphine, isopropanol, and trimethylsilyldiazomethane with RhCl(PPh₃)₃ and copper complexes as catalysts was previously developed by our group. In this research it was determined that Iridium complexes can similarly catalyze the methylenation under identical conditions as used for rhodium and copper catalysts. Moreover, Iridium complexes were efficient to catalyse the olefination of aldehydes using ethyldiazoacetate at room temperature. This catalysed olefination reaction, contrary to those previously reported, can be accelerated by the addition isopanol

Several mechanistic studies using Ruthenium complexes as catalysts in this methylenation reaction have postulated the formation of a N-metallated  metalladiazocyclobutane instead of a carbene complex. This transition state has been observed by NMR analysis, however, the crystal structure was not obtained due to the instability of  diazorhutenium complexes.

However, several crystalised Iridiumdiazo compounds have been reported in the literature and appear to be more stable than those of rhodium or rhuteniumdiazo complexes.

In this work we present the use of iridium complexes as a means to prove the formation of the N-metallated intermediate in the methylenation reaction, as opposed to carbene complex, using crystal analysis.