The hexacarbonyls of chromium, molybdenum, and tungsten react with tricyclo[188.8.131.52(2,7)]undeca-3,5-diene upon UV irradiation in a first step to tetracarbonyl-eta-4-tricyclo[184.108.40.206(2.7)]undeca-3,5-diene-chromium(0) (1), -molybdenum(0) (2) and -tungsten(0) (3). By longer irradiation, dicarbonyl-bis(eta-4-tricyclo[220.127.116.11(2.7)]undeca-3,5-diene)molybdenum(0) (4) and -tungsten(0) (5) are formed. The complexes were purified by chromatography and studied by IR, H-1, and C-13 NMR spectroscopy. The C-13 NMR signals of the CO ligands of 1-3 were found to be temperature dependent owing to a hindered CO scrambling. The H-1 and C-13 NMR signals of 4 and 5 are temperature dependent as well and indicate a hindered enantiomerization of the pseudo-octahedral complexes.