Photodissociation spectra of mass-selected Mg(CH2=CHCN)(n)(+) cluster ions were investigated in the wavelength region from 415 to 225 nm and 495 to 225 nm for n=1 and 2, respectively, by monitoring the total yield of fragment ions. The absorption bands exhibit large shifts from the P-2-S-2 resonance line of Mg+. In the spectrum of n=1, there are two bands at 26 400 and 40 800 cm(-1). On the other hand, three absorption bands at 22 600, 28 800, and 37 500 cm(-1) appear in the spectrum of n=2. The most stable structures in the ground state for n=1 and 2 were obtained by DFT(B3LYP/6-31+G*) calculations, and transition energies from these structures were obtained by using configuration interaction singles approach with the same basis set. The calculated excitation energies show good agreement with the experimental results. In addition, fragment ions of Mg(CH2=CHCN)(m)(+) with m=4 and 5 are found to have high intensities from the parent ions of n=6-10 at a dissociation wavelength of 355 nm. From the result of theoretical calculations for n=3 and 4, a valence electron of Mg+ is found to transfer to the solvating acrylonitrile molecules in these sizes, although this process does not cause an anionic polymerization reaction that observed in alkali metal atom-acrylonitrile neutral clusters. (C) 2003 American Institute of Physics.