It is of considerable interest to prepare weakly ligated, labile ligand (WLLL) nanoparticles for applications in areas such as chemical catalysis. WLLL nanoparticles can be defined as nanoparticles with sufficient, albeit minimal, surface ligands of moderate binding strength to meta-stabilize nanoparticles, initial stabilizer ligands that can be readily replaced by other, desired, more strongly coordinating ligands and removed completely when desired. Herein, we describe WLLL nanoparticles prepared from [Ir(1,5-COD)Cl](2) reduction under H-2, in acetone. The results suggest that H+Cl--stabilized Ir(0)(n) nanoparticles, herein Ir(0)(n)center dot(H+Cl-)(a), serve as a WLLL nanoparticle for the preparation of, as illustrative examples, five specific nanoparticle products: Ir(0)(n)center dot(Cl-Bu3NH+)(a), Ir(0)(n)center dot(Cl(-)Dodec(3)NH(+))(a), Ir(0)(n)center dot(POct(3))(0.2n)(Cl-H+)(b), Ir(0)(n)center dot(POct(3))(0.2n), and the gamma-Al2O3-supported heterogeneous catalyst, Ir(0)(n)center dot(gamma-Al2O3)(a)(Cl-H+)(b). (where a and b vary for the differently ligated nanoparticles; in addition, solvent can be present as a nanoparticle surface ligand). With added POct(3) as a key, prototype example, an important feature is that a minimum, desired, experimentally determinable amount of ligand (e.g., just 0.2 equiv POct(3) per mole of Ir) can be added, which is shown to provide sufficient stabilization that the resultant Ir(0)(n)center dot(POct(3))(0.2n)(Cl-H+)(b) is isolable. Additionally, the initial labile ligand stabilizer HCl can be removed to yield Ir(0)(n)center dot(POct(3))(0.2n) that is >99% free of Cl- by a AgCl precipitation test. The results provide strong support for the weakly ligated, labile ligand nanoparticle concept and specific support for Ir(0)(n)center dot(H+Cl-)(a) as a WLLL nanoparticle.