Unusual outcome of the thermolytic condensation of diazoarylmethanes with a [tricarbonyl(η6-2-p-tolyl)chromium]2-oxazolyl chelate of tetracarbonylrhenium

• A new rhenacycle derived from a 2-phenyl,2-oxazoline was synthesized.
• Its reaction with Ph2CN2 gives a new insertion product.
• The Re centre is engaged in a trihapto-benzyilic interaction.
• Reaction of the rhenacycle with (t-Bu)(Ph)CN2 affords a different product.
• The product seemingly results from insertion of a carbene moiety and intramolecular C–H bond activation.

A new Cr(CO)3-bound cyclorhenated 2-phenyl,2-oxazoline derivative was synthesized and treated with two different phenyldiazomethanes, namely Ph2CN2 and (t-Bu)(Ph)N2 under thermolytic conditions in apolar solvents. With the former diazomethane the reaction affords mainly a new bimetallic electron-saturated species resulting from the insertion of the Ph2C moiety into the CAr–Re bond of the rhenacyclic substrate. With the latter diazomethane substituted with one t-butyl group, the reaction quite unexpectedly leads to a new Re(CO)4 metallacycle in which an ortho position is occupied by a (Ph)(t-Bu)(H)C-group, as a possible consequence of an unprecedented insertion–transposition of the Re-centred moiety by C–H bond activation. The results are supported by 6 X-ray structures and analytical informations.

Treatment of a π-complex of a rhenacycle by a phenyldiazomethane induces the successive insertion of a carbene ligand and the rhenium transposition via a probable C–H activation route.Figure optionsDownload as PowerPoint slide