[RhIII(*Cp)Cl(X,Y)]<
sup>
n+<
/sup>
complexes {X, Y = Cl, PTA, n = 0 (2)
X, Y = en, n = 1 (3, Cl? salt
4, PF<
sub>
6<
/sub>
? salt)
X, Y = acac, n = 0 (5)
X, Y = cur, n = 0 (6), where *Cp = pentamethylcyclopentadienato, curH = curcumin
PTA = 1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane
en = 1,2-ethanediamine
acac = acetylacetonato = 2,4-pentanedionato(1?)} were synthesized from [Rh(*Cp)(�-Cl)Cl]<
sub>
2<
/sub>
(1). While 2?5 were inactive against human epithelial A549 lung-cancer cells in assays of cytotoxicity, and antimetastatic and proapoptotic behaviors, 6 had a cytotoxic activity similar to that of curH over 72 h, but at 24 h in real-time cell migration assays, it was less active, showing slow release of curH. All complexes underwent ligand-exchange reactions with biomolecules and cells within the timeframes of the assays (X-ray absorption spectroscopy). Intracellular elemental distributions (X-ray fluorescence microscopy) showed that 6 effectively delivered curH to cells, where it was released. Other elemental distributions and caspase activities were consistent with preapoptotic activities. As such, 6 is a promising delivery agent for bioactive ligands, such as curH. However, pure curcumin itself showed a previously unrecognized ability to promote migration of A549 cells at subtoxic concentrations in the presence of endothelial growth factor, which may be a concern for its widespread use as a nutritional supplement and as a potential drug. As a result, this aspect warrants further research.