The infrared multiphoton dissociation (IRMPD) of the two isomers, M(1,3-butadiene)(+) and M(C2H2)-(C2H4)(+) (M = Fe, Co, or Ni), was investigated. For the butadiene system, FeC4H6+ was observed to give three products, CoC4H6+ four products, and NiC4H6+ Only one product. The observation of four products has not been previously seen in IRMPD studies of ions and suggests a fortuitous balance of several factors. Interestingly, the IRMPD of M(butadiene-1,1,4,4-d(4))(+) was observed not only to give one product for M = Fe, Co, or Ni but also to proceed with a decreased photodissociation rate. For the M(C2H2)(C2H4)(+) system, IRMPD suggests that D-o(Co+-C2H2) similar to D-o(CO+-C2H4) Also, SORI and/or competitive CID indicate that D-o(M(+)-C2H2) > D-o(M(+)-C2H4) by 0.5-2 kcal/mol for M = Fe or Ni. On the basis of these observations, we assign D-o(Fe+-C2H2) = 6 +/- 2 kcal/mol, D-o(Co+-C2H2) = 43 +/- 2 kcal/mol, and D-o(Ni+-C2H2) = 45 +/- 2 kcal/mol. These results are compared to recent theoretical and experimental findings.