Oxygen transfer from chromyl chloride to alkynes and allene - IR-spectroscopic identification of eta(1)-ketene and cyclopropanone complexes of O=CrCl2

Photolytically-induced reactions of chromyl chloride with acetylene and but -2-yne (dimethylacetylene) in low-temperature argon matrices yield end-on k etene and dimethylketene complexes of O=CrCl2, respectively. The product fo rmation probably results from an electrophilic attack of a Cr=O linkage on the C equivalent to C triple bonds, leading to radical-like transition stat es or intermediates, which subsequently rearrange through 1,2-H or 1,2-meth yl shifts. Consequently, allene is attacked at its central carbon and the a llyl radical thus generated undergoes subsequent. ring-closure to give a cy clopropanone complex of O=CrCl2.