Coordination properties of the oxime analogue of glycine to Cu(II).
The coordination of Cu2+ by glyoxilic acid oxime (gao)--the oxime analogue of glycine amino acid--and its deprotonated (gao- and gao2-) species has been studied with different density functional methods. Single-point calculations have also been carried out at the single- and double- (triple) excitation coupled-cluster (CCSD(T)) level of theory. The isomers studied involve coordination of Cu2+ to electron-rich sites (O,N) of neutral, anionic, and dianionic gao species in different conformations. In contrast to Cu2+-glycine, for which the ground-state structure is bidentate with the CO2(-) terminus of zwitterionic glycine, for Cu2+-gao the most stable isomer shows monodentate binding of Cu2+ with the carbonylic oxygen of the neutral form. The most stable complexes of Cu2+ interacting with deprotonated gao species (gao- and gao2-) also take place through the carboxylic oxygens but in a bidentate manner. The results with different functionals show that, for these open shell (Cu2+-L) systems, the relative stability of complexes with different coordination environments (and so, different spin distribution) can be quite sensitive to the amount of "Hartree-Fock" exchange included in the functional. Among all the functionals tested in this work, the BHandHLYP is the one that better compares to CCSD(T) results.
Georgieva
I
I
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Trendafilova
N
N
Rodríguez-Santiago
L
L
Sodupe
M
M
D000838:Anions; D002264:Carboxylic Acids / Q000737:chemistry; D002413:Cations, Divalent; D003300:Copper / Q000737:chemistry*; D004583:Electrons; D005998:Glycine / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D010091:Oximes / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D011522:Protons; D013816:Thermodynamics
D000838:Anions; D002264:Carboxylic Acids; D002413:Cations, Divalent; D010091:Oximes; D011522:Protons; D003300:Copper; D010100:Oxygen; D005998:Glycine