Conclusions. The reaction of the carbene-like terminal phoephinidene complex Ph-PW (CO) 5 with the activated cyclic diene 3 yields as primary product the bicyclic phoephirane 4 in high stereomlectivity. It is suggeeted that this selectivity is determined early on the reaction path and results from repulsive interactions between the P-phenyl and diene groups. Tricyclic phospholene 5 is not a primary (1, 4addition) product from diene 3, but rather a ...