The elementary steps of the reactions of hypophosphite ions with Cu, Ni, and Pd were calculated theoretically using Density Functional Theory (DFT) to demonstrate the reaction mechanism and gain insight at the molecular level. The elementary steps of these reactions are adsorption, dehydrogenation, and oxidation (hydroxyl base attack). In the adsorption step, hypophosphite ions adsorb onto each surface spontaneously with stabilities in the order of Ni (111) > Pd (111) > Cu (111). In the dehydrogenation step, hypophosphite ions dehydrogenate on Ni (111) and Pd (111) with small reaction barriers, whereas they react on Cu (111) with a large reaction barrier. The large reaction barrier on Cu (111) is not compensated for by the adsorption energy on the surface. In the oxidation step, dehydrogenated anions on each metal surface react spontaneously with the hydroxyl base. The reaction barriers on each metal surface in this step are not so significant compared to the adsorption energies on each surface, suggesting that a reaction barrier of hypophosphite ion oxidation should exist in the dehydrogenation step and only be observed for Cu (111). This proposition elucidates the experimental catalytic behaviors of metal surfaces in the electroless deposition process using hypophosphite ions.

No abstract

No abstract

No abstract

Oxidation reaction mechanisms of reductants for electroless Ag deposition process were investigated using density functional theory calculation, focusing upon behavior of the reaction intermediate species. It was indicated that the oxidation processes of reductants, such as dimethylamine borane, formaldehyde, and hypophosphite ion, on the Ag surface are initiated by addition of OH − and proceed via five-coordinate intermediate species. Catalytic activity of the Ag surface for the oxidation reaction of the reductants was investigated by using energy density analysis, focusing upon the local interaction of the species. The results indicated that the adsorption of the reductants onto the Ag surface is driven by destabilization of the reductant and stabilization of the Ag surface. It was also indicated that the destabilization of the five-coordinate intermediate species at the Ag surface is a key factor of the "catalytic activity" for the oxidation reaction. In the case of the reaction of formaldehyde, in which the Ag surface acts as catalyst, the intermediates were considerably activated at the Ag surface, whereas such an effect was not clearly seen with the hypophosphite ion, for which the Ag surface is not catalytic. It was also suggested that the activation of the intermediates is affected by coordination behavior of OH − species.