Theoretical studies of Zn

Area of Science:

• Coordination Chemistry
• Computational Chemistry
• Materials Science

Background:

• Xanthates are versatile organic compounds with significant interest in coordination chemistry.
• They exhibit diverse bonding modes with metal ions, leading to various applications.
• Key applications include heavy metal remediation, biological activities (anti-bacterial, anti-cancer), and materials science as sulfide precursors.

Purpose of the Study:

• To investigate the thermochemical and electronic properties of zinc complexes substituted with n-propyl, n-butyl, and n-pentyl xanthate ligands.
• To analyze the substitution reactions of water molecules in aqua zinc complexes by xanthate ligands.
• To elucidate the electronic structure and bonding characteristics of the resulting zinc-xanthate complexes.

Main Methods:

• Theoretical studies employing Density Functional Theory (DFT) at multiple levels (M06L, M06-2X, wB97XD, B3LYP/6-311++G**+LANL2TZ).
• Optimization and normal mode calculations using Gaussian09.
• Analysis of sequential substitution stages (cationic and neutral complexes).
• Electronic Energy Decomposition (EDA) and Natural Bond Orbital (NBO) analysis at the M06L/6-311++G**+LANL2TZ level using Gamess.

Main Results:

• Formation of zinc complexes with distorted octahedral geometries.
• Negative enthalpy and Gibbs free energy values, indicating exothermic and spontaneous substitution processes.
• Zn2+ complexes exhibit both ionic and covalent character, with a predominance of ionic character in monosubstituted complexes.
• High donor-acceptor interaction energies suggest significant orbital overlap in the Zn-S bond.

Conclusions:

• The substitution of aqua ligands by xanthates in zinc complexes is thermodynamically favorable and spontaneous.
• The electronic structure of these complexes is characterized by a mix of ionic and covalent bonding, with implications for their stability and reactivity.
• The findings support the potential of xanthates in applications requiring metal complexation and sulfide material synthesis.