Ternary copper(II) complexes with N-carboxymethyl-l-prolinato(2-) ion and imidazole or creatinine: a comparative study of the interligand interactions influencing the molecular recognition and stability.
The compounds {[Cu(CMP)(Him)].H(2)O}(n) (I) and [Cu(CMP)(crea)H(2)O].3H(2)O (II) were synthesized and characterized by X-ray diffraction, thermal, spectral and magnetic methods (CMP=N-carboxymethyl-;l-prolinato(2-) ion, Him=imidazole and crea=creatinine). Appropriate structural comparison with other compounds such as {[Cu(CMP)(H(2)O)].H(2)O}(n), [Cu(crea)(2)Cl(2)] and [Cu(dipeptide)(crea)(H(2)O)(x)].nH(2)O (x=0 or 1) have been made in order to prove that crea can act as an imidazole-like ligand (because it is able to promote the same fac- to mer-CMP tridentate conformational change in copper(II) complexes) as well as to discuss the interligand interactions which control the 'Cu(CMP) complex-crea, molecular recognition processes. In contrast to that found in related ternary complexes, we have concluded that direct CMP-crea interligand interactions are missing in the Cu-CMP-crea complex due to the inappropriate correspondence between the donor and/or acceptor H-bonding properties of these ligands. CMP can only act as H-acceptor by its two terminal carboxylate group, and crea can display H-donor and H-acceptor roles by its exocyclic -NH(2) and O moieties, respectively. That promotes the reinforcement of the Cu-N(crea) bond by a bridge -N-H(crea)...O(aqua) (2.867(3)A, 176.4 degrees).
Tribet
M
M
Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, E-18071Granada, Spain.
Covelo
B
B
Sicilia-Zafra
A G
AG
Navarrete-Casas
R
R
Choquesillo-Lazarte
D
D
González-Pérez
J M
JM
Castiñeiras
A
A
Niclós-Gutiérrez
J
J
D003300:Copper / Q000737:chemistry*; D003404:Creatinine / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007093:Imidazoles / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry*
D007093:Imidazoles; D008024:Ligands; D009942:Organometallic Compounds; D003300:Copper; C029899:imidazole; D011392:Proline; D003404:Creatinine