A detailed study has been undertaken of the infrared multiphoton chemistry of complexes of the general form M+(C2H5OH)(n), where M is chromium, manganese, iron, cobalt, or nickel and n is either 1 or 2. The ions have been prepared via ligand stripping from volatile metal-carbonyl compounds and held in an ion trap, where photofragment intensities have been recorded as a function of CO2 laser frequency by using radiation from a line-tuneable laser. All the metal complexes exhibit structured photofragmentation patterns as a function of laser frequency, and the results are consistent with the absorber being an adduct of M+ bonded to ethanol via ion-dipole and -induced dipole interactions. For the metals Fe, Ni, and Co, photoexcitation of the complex promotes a dehydration reaction, whereas for Mn and Cr, the metal ion-ethanol bond is broken upon photoexcitation. In association with iron, the efficiency of the photoexcitation process is very dependent upon isotopic substitution, and the relative intensities of H2O, DHO, and D2O from complexes composed of mixtures of isotopomers show evidence of both primary and secondary isotope effects. Overall, the results show a strong correlation between the reaction pathway of an ion complex and the electronic spin configuration of the metal ions concerned. Those metal ions that are in low spin states with no 4s electrons are found to exhibit the dehydration reaction.