fluorophenylcarbene were generated in water-doped argon matrices at cryogenic temperatures by photolysis of the corresponding matrix-isolated diazirines. When diffusion of H2O in solid argon was induced by annealing of the matrices at temperatures above 20 K, hydrogen-bonded complexes between the carbenes and water were formed. UVphotolysis of these complexes resulted in the formation of benzaldehyde