“…In the case of complicated systems (i.e., systems involving several complexes, or systems in which polynuclear species are present), potentiometric, spectrophotometric, and calorimetric data may leave some ambiguity in the identification of the correct model. In these cases, supplementary qualitative information can be acquired from NMR (Di Marco et al, 1999) and, less frequently, from other spectroscopic techniques as CD (Daniele, Prenesti, & Ostacoli, 1996), IR (Bombi et al, 1990), and EPR (Di Marco et al, 2004). In the few cases in which suitable crystals are obtained, X-ray diffractometry can indirectly confirm the stoichiometry of one of the species in solution .…”