Gas-phase ligand exchange between volatile lanthanide dipivaloylmethanates (Ln(dpm)3; Hdpm is dipivaloylmethane, Ln = Tb, Lu) and o-substituted aromatic carboxylic acids (HCarb = Hsal is o-hydroxybenzoic acid, Habz is o-aminobenzoic acid, Hpobz is o-phenoxybenzoic acid, Hpa is o-anilinobenzoic acid). The gas-phase reaction involves the formation of the mixed-ligand complex Ln (dpm)3−n (Carb)n, which is subsequently converted into tris-carboxylate (Ln(Carb)3) on heating of the product in vacuum.