Coordination Properties of the Oxime Analogue of Glycine to Cu(II)

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2005-06, Vol.109 (25), p.5668-5676
• Main Authors: Georgieva, I, Trendafilova, N, Rodríguez-Santiago, L, Sodupe, M
• Format: Article
• Language: English
• Subjects: Anions; Carboxylic Acids - chemistry; Cations, Divalent; Copper - chemistry; Electrons; Glycine - chemistry; Isomerism; Models, Molecular; Oximes - chemistry; Oxygen - chemistry; Protons; Thermodynamics
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp050626h

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.