Unprecedented addition reaction-induced gold(I) cluster-to-cluster transformation has been observed in the present work. Reaction of the chlorogold(I) precursor, [vdpp(AuCl)(2)] (vdpp = vinylidenebis(diphenylphosphine)) containing the diphosphine with unsaturated C=C bond, with H2S resulted in a series of polynuclear gold(I) mu(3)-sulfido clusters bearing Au(I)center dot center dot center dot Au(I) interactions; the identities of which have been fully characterized by NMR, electrospray-ionization mass spectrometry, elemental analysis, and single crystal X-ray diffraction analysis. Diverse research methods, including UV-vis absorption, H-1 NMR, and P-31 NMR spectroscopy, were employed to detect and monitor the transformation and assembly processes. Supported by single crystal structures, the existence of Au(I)center dot center dot center dot Au(I) bonding interactions sustains the diverse array of sophisticated polynuclear cluster structures and endues them with rich luminescence features.