Triphenylphosphine-cappped, 1.5-nm gold nanoparticles "Au-101-(PPh3)(21)Cl-5" prepared following Hutchison's procedure (Weare, W. W.; Reed, S. M.; Warner, M. G.; Hutchison, J. E. J. Am. Chem. Soc. 2000, 122, 12890) undergo rapid exchange of capping ligand phosphine with dissociated and added phosphine in dichloromethane solvent at 298 K. Remarkably, while the H-1 NMR spectrum resonances of the attached phosphine are broad, characteristic of a range of incompletely averaged environments, the P-31 NMR spectrum (observable only at 213 K and below) exhibits a single, narrow resonance indicating that all of the phosphorus atoms are magnetically equivalent.