Photoinduced reactions of bidentate metal complexes Mg+(2-methoxyethanol), Mg+(1,2-dimethoxyethane), and Mg+(1,2-diaminoethane) have been studied combining mass-selective photodissociation spectroscopy and quantum mechanical calculations. Besides the evaporative fragment cation Mg+, copious reactive channel photoproduct cations have been identified, which are propagated from the well-defined bidentate chelation structures upon photoexcitation of Mg+. For Mg+(2-methoxyethanol) and Mg+(1,2-dimethoxyethane), most reactive channel photoproducts are actually Mg+-molecule complexes, such as Mg+(H2O), Mg+(HCHO), Mg+(CH3OH), Mg+(C2H6O), etc. with an exception of Mg+OH. The reactive channel photoproducts of Mg+(1,2-diaminoethane) consist of a cationic complex Mg+(H2NCH3) and two other cations CH2NH2+ and Mg+NH2, which are formed from the cleavage of the C-C and C-N bonds, respectively. Action spectra and branching fractions of all of the observed photofragments have been measured in a broad spectral range of 230-440 ran and analyzed against ab initio calculations. A hydrogen shift mechanism is proposed, whereby a critical hydrogen-shift step opens doors to the subsequent reactions. This mechanism appears to run through most photoreactions of the three complexes.