Synthetic inorganic chemistry recently has made use of the nucleophilic properties of hydroxo metal complexes to synthesize carboxylato metal compounds. The carboxylation of dihydroxoplatinum(IV) compounds by acyl chlorides is described, a method in inorganic chemistry which makes use of the classical organic carboxylation agent. The trans-R,R- and trans-S,S-isomers of (OC-6-33)-bis(1-adamantanecarboxylato)(cyclohexane-1,2-diamine)dichloroplati num(IV) were synthesized by acylation of hydroxide coordinated to platinum(IV), characterized by elemental analysis as well as IR and NMR spectroscopy, and the crystal structures were resolved.