Therefore, at the initial stages of film growth, the surface reactions between metal precursors and the starting substrate and the corresponding chemistries are vital to understand the reaction mechanism behind the deposition process and any nucleation delay. In studying nucleation of a film in an ALD process, we consider that the first step of precursor adsorption followed by ligand elimination is crucial. Providing the atomic level details of the Co and Ru precursor chemistry at a series of differently terminated silicon surfaces is the key advance of the current paper.