Electrospray ionization of aqueous solutions of magnesium(II) acetate leads to microhydrated magnesium
acetate cations of the type [(CH3COO)2m-1Mgm(H2O)n]+ with m = 1 - 4 and n = 0 - 4, which are 
characterized by mass spectrometry and, for the cluster with three water molecules, also by infrared 
multiphoton dissociation spectroscopy. Density functional theory is used to determine the energies 
of microhydration for the mononuclear species [(CH3COO)Mg(H2O)n]+ with n = 0 - 6 and the associated 
changes in molecular structure. While bidentate coordination of the acetato ligand is generally 
preferred, at higher values of n a switch to a monodentate coordination becomes energetically competitive.