The synthesis of the molybdenum allyl complexes Tp*Mo(CO)2(h3-crotyl), TpMo(CO)2(h3-cyclohexenyl) (3a), Tp*Mo(CO)2(h3-cyclohexenyl) (3b), TpMo(CO)2(h3-cycloheptenyl) (4), and Tp*Mo(CO)2(h3-cyclooctenyl) [Tp = hydridotrispyrazolylborato, Tp* = permethylated Tp] is described. The cyclic complexes 3 and 4 are converted to the cationic molybdenum diene complexes [TpMo(CO)2(h4-cyclohexadiene)]+ PF6- (7) upon treatment with Ph3CPF6. Complexes, e.g., 7 react stereoselectively from the non-metal side with a broad range of nucleophiles. The crystal structure data anal. of 4 is discussed.