Matrix isolation study into the mechanism of photoinduced cyclization reactions of chromium carbenes

This study investigates the difference in reactivity between tungsten and chromium carbenes with respect to their ability to undergo photoinduced reactions with organic compounds to form cyclic molecules such as β-lactams. Three complexes have been studied: (CO)5M[C(OMe)(Me)] (M = Cr, W) and (CO)5Cr[C(OMe)(biphenyl)]. Our study supports the proposal that the reaction mechanism does not involve CO loss. We propose that the excited state involved in the photochemical reactions is the lower energy ligand field state