Nanoparticles are targeted as superior materials for catalytic applications. Their templated synthesis with PAMAM dendrimers in aqueous solution can be preceded by the complexation of metal precursors with such molecules. Understanding of this step is crucial to determine properties such as maximum load, sites of complexation, etc. However such a study ought to be done in a case by case basis so specific variables such as salt hydrolysis, solvent , pH, and counterion effects are accounted. We calculate thermodynamic quantities with two dendrimer fragment models selected to represent both a protonated and an unprotonated tertiary amine site. Speciation of tetrachloroplatinate anion and binding of potassium and chloride ions are modeled. All calculations were done with Gaussian03. Although the calculations still lack the solvent effect, they provide qualitative insights regarding factors that may explain experimental trends; especially in the first stages of anionic complexation when the interaction dendrimer-precursor is expected to occur mostly in the dendrimer outer pockets formed by two or more branches at the dendrimer surface.