The N,N',O-heteroscorpionate ligand 1-(4-methoxy-3,5-dimethyl-pyridin-2-yl)-2-methyl-1-pyrazol-1-yl-propan-2 -ol (LOH) was prepared in two high-yield steps. Complexes [M(LOH)(2)][MCl4] (M2+ = Cu2+ and Zn2+) and [M(LOH)(2)]Cl-2 (M2+ = Ni2+ and Cu2+) were prepared and characterized by X-ray crystallography. The speciation in solution (methanol:water 95:5) of the M2+/LOH systems was investigated by means of spectrophotometric (Ni2+ and Cu2+) and H-1 NMR (Zn2+) titrations. The beta(1) and beta(2) global formation constants for the [M(LOH)](2+) and [M(LOH)(2)](2+) species were obtained and are in agreement with the Irving-Williams series: Ni2+< Cu2+> Zn2+. The Zn2+/LOH system was studied by means of quantitative H-1-H-1 EXSY spectroscopy (300 K, mixing time = 0.2-0.8 s), which allows the description of the equilibria occurring between five octahedral [Zn(LOH)(2)](2+) structural isomers and tetrahedral [Zn(LOH)Cl]Cl species. Exchange constants k(ij)(ex) and associated rate constants k(ij) suggest that two types of interconversion occur: octahedral-octahedral (faster) and octahedral-tetrahedral (slower). DFT calculations (B3LYP/6-311+G(d)) were employed to evaluate the relative stability of the [Zn(LOH)(2)](2+) isomers, which are comparable for the five complexes with a maximum energy difference of 6.3 kJ/mol.