Synthesis and X-ray structure of a cyclopropane precursor alkene–carbene complex of tungsten in which the two functions are parallel

Photolysis of pentacarbonyl pent-4-enyl (methoxy)carben tungsten(4) at low temperature affords a new chelated alkene–carbene complex (5) in which, according to an X-ray analysis, the alkene and the carbene functions are parallel, and which decomposes to give the expected cyclopropane (7).