Copper cation interactions with biologically essential types of ligands: a computational DFT study.
This work presents a systematic theoretical study on Cu(I) and Cu(II) cations in variable hydrogen sulfide-aqua-ammine ligand fields. These ligands model the biologically most common environment for Cu ions. Molecular structures of the complexes were optimized at the density functional theory (DFT) level. Subsequent thorough energy analyses revealed the following trends: (i) The ammine complexes are the most stable, followed by those containing the aqua and hydrogen sulfide ligands, which are characterized by similar stabilization energies. (ii) The most preferred Cu(I) coordination number is 2 in ammine or aqua ligand fields. A qualitatively different binding picture was obtained for complexes with H(2)S ligands where the 4-coordination is favored. (iii) The 4- and 5-coordinated structures belong to the most stable complexes for Cu(II), regardless of the ligand types. Vertical and adiabatic ionization potentials of Cu(I) complexes were calculated. Charge distribution (using the natural population analysis (NPA) method) and molecular orbital analyses were performed to elucidate the nature of bonding in the examined systems. The results provide in-depth insight into the Cu-binding properties and can be, among others, used for the calibration of bioinorganic force fields.
Pavelka
Matej
M
Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic.
Simanek
Milan
M
Sponer
Jirí
J
Burda
Jaroslav V
JV
D000465:Algorithms; D000641:Ammonia / Q000737:chemistry*; D002412:Cations; D003198:Computer Simulation; D003300:Copper / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000737:chemistry*; D008024:Ligands; D008954:Models, Biological; D008958:Models, Molecular; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D002412:Cations; D008024:Ligands; D014867:Water; D000641:Ammonia; D003300:Copper; D006862:Hydrogen Sulfide