The configuration of zinc is 1s2 2p6 3s2 3d10 4s2. Hence zinc has a valence of two i.e., the valence two electrons participate in the chemical reactions of zinc and are responsible for the chemical reactivity of zinc. The oxidation state of zinc after donating the two electrons becomes Zn+2 making it a divalent atom. A new research conducted by Puru Jena, Ph.D. at Virginia Commonwealth University states that zinc can be made trivalent by reacting it with suitable reagent, which changes its fundamental chemistry.
Zinc is classified as transition metal & a D- block element. Zinc has complete D shell configuration, i.e., it has d10 electronic configuration in ground state imparting higher stability. Unlike other transition metals zinc has completely filled d orbitals hence it is not magnetic in nature. Although Jena discovered that this property of zinc can be changed if it is subjected to react with highly stable trianions. He found out that the electrons in third shell of zinc i.e., d shell electrons can carry a magnetic moment modifying the reactivity of zinc.
Oxidation state influences the chemistry of an element. The other transition metals have unfilled d shells and hence they can exhibit multiple oxidation states. According to the density functional theory, it is demonstrated that zinc can become a trivalent atom by reacting with highly stable super electrophilic trianions, BeB11(CN)123- and BeB23(CN)223-. The energy of these trianions is lowered by 15.85eV & 18.49eV respectively compared to their neutral states.
Optimized geometries of (A) BeB11(CN)123−, (B) BeB23(CN)223−, (C) neutral ZnBeB11(CN)12 and (D) neutral ZnBeB23(CN)22. Boron atoms depicted in green, carbon in grey, nitrogen in blue, beryllium in orange and zinc in cyan.
It means that BeB11(CN)12 and BeB23(CN)22are super electrophilic agents & they can accept three additional electrons maintaining higher stability than their neutral species. It is evident by the large binding energies of 6.33 and 7.04eV with BeB11(CN)123− and BeB23(CN)223−, respectively, that zinc exists in +3 oxidation state. These clusters can mimic the group 15 elements. The comprehensive analysis of its bonding characteristics, electron localization function, molecular orbitals, charge density distribution and energy decomposition indicate that its 3d electrons are strongly involved in chemical bonding. When CN is replaced with BO, the binding energy of zinc is increased.
Calculated charge density differences for ZnBeB23(CN)22 (left) and ZnBeB11(CN)12 (right) in the three N–Zn–N planes (top panel) for the three Zn–N bonds in 2D as well as in 3D.
Reference: Hong Fang, Huta Banjade, Deepika, Puru Jena. Realization of the Zn3+ oxidation state.
Nanoscale, 2021; DOI: 10.1039/D1NR02816B
Blog by Aditi Ranade
Bình luận