Reactions of laser-ablated palladium and platinum atoms with ethylene isotopomers have been carried out in excess argon during condensation at 7 K. Infrared spectra show that palladium forms a pi complex with ethylene whereas platinum generates an insertion product. Acetylene is a major product, suggesting that H-2 elimination from ethylene is also induced by the metal atom reactions. Product frequencies calculated by DFT are compared with the experimental values.