Chromium-Templated Benzannulation of (η5-Cyclohexadienyl)Mn(CO)3-Methoxy-Cr(CO)5 Carbenes

Pentacarbonyl­{methoxy-[1-(η5-4-methoxy-6-phenylcyclohexadienyl)­tricarbonylmanganese]­carbene}­chromium (5) accessible from (η5-1-bromo-4-methoxy-6-phenylcyclohexadienyl)­tricarbonylmanganese (4) and Cr­(CO)6 undergoes a chromium-templated benzannulation with 3-hexyne to give monometallic Cr complex 12 in 60% yield. The key feature of this reaction is the participation of a conjugated double bond of the η5-cyclohexadienyl-Mn moiety in the [3+2+1] benzannulation reaction. The X-ray structure of complex 12 reveals a syn position of the phenyl group with respect to the Cr tripod, supporting the participation of the Mn moiety in the benzannulation process.