Reaction of Na[eta(5)-(C5H4Pr)-Pr-i] with W(CO)(6) in refluxing THE for 4 days generates a solution of Na[(eta(5)-(C5H4Pr)-Pr-i)W(CO)(3)] that when treated with N-methyl-N-nitroso-p-toluenesulfonamide at ambient temperatures affords (eta(5)-(C5H4Pr)-Pr-i)W(NO)(CO)(2) (1) that is isolable in good yield as an analytically pure orange oil. Treatment of 1 with an equimolar amount of I-2 in Et2O at ambient temperatures affords (eta(5)-(C5H4Pr)-Pr-i)W(NO)I-2 (2) as a dark brown solid in excellent yield. Sequential treatment at low temperatures of 2 with 0.5 equiv of Mg(CH2CMe3)(2) and Mg(CH2CH=CMe2)(2) in Et2O produces the alkyl allyl complex, (eta(5)-(C5H4Pr)-Pr-i)W(NO)(CH2CMe3)(eta(3)-CH2CH2CMe2) (3), as a thermally sensitive yellow liquid. Complex 3 may also be synthesized, albeit in low yield, in one vessel at low temperatures by reacting 1 first with 1 equiv of PCl5 and then with the binary magnesium reagents specified above. Interestingly, similar treatment of 1 in E2O with PCl5 and only 0.5 equiv of Mg(CH2CH=CMe2)(2) results in the formation of the unusual complex (eta(5)-(C5H4Pr)-Pr-i)W(NO)(PCl2CMe2CH=CH2)Cl-2 (4), which probably is formed via a metathesis reaction of the binary magnesium reagent with (eta(5)-(C5H4Pr)-Pr-i)W(NO)(PCl3)Cl-2. The C-D activation of C6D6 by complex 3 has been investigated and compared to that exhibited by its (eta(5)-C5Me5, eta(5)-C5Me4H, and eta(5)-C5Me4 '' Pr analogues. Kinetic analyses of the various activations have established that the presence of the eta(5)-(C5H4Pr)-Pr-i ligand significantly increases the rate of the reaction, an outcome that can be attributed to a combination of steric and electronic factors. In addition, mechanistic studies have established that in solution 3 loses neopentane under ambient conditions to generate exclusively the 16e eta(2)-diene intermediate complex (eta(5)-C(5)H(4)iPr)W(NO)(eta(2)-CH2=CMeCH=CH2), which then effects the subsequent C-D activations. This behavior contrasts with that exhibited by the eta(5)-C5Me5 analogue of 3 which forms both eta(2)-diene and eta(2)-allene intermediates upon thermolysis. Sixteen-electron (eta(5)-(C5H4Pr)-Pr-i)W(NO)(eta(2)-CH2=CMeCH=CH2) has been isolated as its 18e PMe3 adduct. All new organometallic complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of two of them have been established by single-crystal X-ray crystallographic analyses.