TY - JOUR
T1 - Coordination of imidazoles by Cu(II) and Zn(II) as studied by NMR relaxometry, EPR, far-FTIR vibrational spectroscopy and ab initio calculations
T2 - effect of methyl substitution
AU - Andersson, Markus
AU - Hedin, Jesper
AU - Johansson, Patrik
AU - Nordström, Jonas
AU - Nydén, Magnus
PY - 2010/12/23
Y1 - 2010/12/23
N2 - Synthetic imidazole ligands are typically substituted at the N1 ((1)-Im) position while natural imidazole ligands are substituted at the C 4 ((4)-Im) position. To outline the difference in coordination properties, the methyl-substituted imidazoles Me(4)-Im and Me(1)-Im were complexed with CuCl2 and ZnCl2 and investigated by NMR relaxometry, electron paramagnetic resonance, far-Fourier transform IR vibrational spectroscopy, and ab initio calculations. Me(4)-Im, Me(1)-Im, and Im in excess form the usual tetragonal D4h [CuL4X 2] complexes with CuCl2 whereas the methylated imidazoles form pseudotetrahedral C2v complexes instead of the usual octahedral Oh [ZnIm6]2+ complex. All imidazoles display a high degree of covalence in the M-L σ- and π-bonds and the π-interaction strength affects the relative energies of complexation. Opportunities to tailor complexes by the chemical properties of the substituents are envisaged due to the role of the inductive and hyperconjugative effects, rather than position.
AB - Synthetic imidazole ligands are typically substituted at the N1 ((1)-Im) position while natural imidazole ligands are substituted at the C 4 ((4)-Im) position. To outline the difference in coordination properties, the methyl-substituted imidazoles Me(4)-Im and Me(1)-Im were complexed with CuCl2 and ZnCl2 and investigated by NMR relaxometry, electron paramagnetic resonance, far-Fourier transform IR vibrational spectroscopy, and ab initio calculations. Me(4)-Im, Me(1)-Im, and Im in excess form the usual tetragonal D4h [CuL4X 2] complexes with CuCl2 whereas the methylated imidazoles form pseudotetrahedral C2v complexes instead of the usual octahedral Oh [ZnIm6]2+ complex. All imidazoles display a high degree of covalence in the M-L σ- and π-bonds and the π-interaction strength affects the relative energies of complexation. Opportunities to tailor complexes by the chemical properties of the substituents are envisaged due to the role of the inductive and hyperconjugative effects, rather than position.
UR - http://www.scopus.com/inward/record.url?scp=78650387427&partnerID=8YFLogxK
U2 - 10.1021/jp1062868
DO - 10.1021/jp1062868
M3 - Article
C2 - 21114301
AN - SCOPUS:78650387427
SN - 1089-5639
VL - 114
SP - 13146
EP - 13153
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 50
ER -