Electron-phonon coupling constants are calculated for organic molecular crystals of anthracene, tetracene, and pentacene and their full deuterides. We find that the low-frequency C-C-C in-plane modes of 200-400 cm(-1) and the C-C stretching modes of 1400-1600 cm(-1) play an important role in the electron-phonon coupling in these acenes. Inverse isotope effects for hydrogen-deuterium substitution are predicted in the superconductivity of acenes. Such inverse isotope effects can be explained by electron-phonon couplings in the C-C stretching modes, which significantly increase by deuterium substitution.