A detailed vibrational study on the isomers 2,2′-dithiodipyridine and 4,4′-dithiodipyridine was carried out. These organic ligands are of great interest as possible linkers in the fabrication of nanostructures, and therefore a study on the adsorption modes of both ligands at silver surfaces is presented. Orientational information on the 2,2′-dithiodipyridine and 4,4′-dithiodipyridine molecules adsorbed on silver colloids was collected based on the SERS spectra and supported by ab initio calculations. There is evidence that both organic ligands adsorb on the silver surface through the sulfur atoms, with the aromatic rings in a tilted position.