View : 102 Download: 0

Axial ligand effects on the geometric and electronic structures of nonheme oxoiron(IV) complexes

Title
Axial ligand effects on the geometric and electronic structures of nonheme oxoiron(IV) complexes
Authors
Jackson T.A.Rohde J.-U.Mi S.S.Sastri C.V.DeHont R.Stubna A.Ohta T.Kitagawa T.Munck E.Nam W.Que Jr. L.
Ewha Authors
남원우서미숙
SCOPUS Author ID
남원우scopus
Issue Date
2008
Journal Title
Journal of the American Chemical Society
ISSN
0002-7863JCR Link
Citation
vol. 130, no. 37, pp. 12394 - 12407
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
A series of complexes [FeIV(O)(TMC)(X)]+ (where X = OH-, CF3CO2-, N3-, NCS-, NCO-, and CN-) were obtained by treatment of the well-characterized nonheme oxoiron(IV) complex [FeIV(O)(TMC)-(NCMe)]2+ (TMC = tetramethylcyclam) with the appropriate NR4X salts. Because of the topology of the TMC macrocycle, the [FeIV(O)(TMC)(X)]+ series represents an extensive collection of S = 1 oxoiron(IV) complexes that only differ with respect to the ligand trans to the oxo unit. Electronic absorption, Fe K-edge X-ray absorption, resonance Raman, and Mössbauer data collected for these complexes conclusively demonstrate that the characteristic spectroscopic features of the S = 1 FeIV=O unit, namely, (i) the near-IR absorption properties, (ii) X-ray absorption pre-edge intensities, and (iii) quadrupole splitting parameters, are strongly dependent on the identity of the trans ligand. However, on the basis of extended X-ray absorption fine structure data, most [FeIV(O)(TMC)(X)]+ species have Fe=O bond lengths similar to that of [FeIV(O)(TMC)(NCMe)]2+ (1.66 ± 0.02 Å). The mechanisms by which the trans ligands perturb the Fe IV=O unit were probed using density functional theory (DFT) computations, yielding geometric and electronic structures in good agreement with our experimental data. These calculations revealed that the trans ligands modulate the energies of the Fe=O σ- and π-antibonding molecular orbitals, causing the observed spectroscopic changes. Time-dependent DFT methods were used to aid in the assignment of the intense near-UV absorption bands found for the oxoiron(IV) complexes with trans N3-, NCS-, and NCO- ligands as X--to-Fe IV=O charge-transfer transitions, thereby rationalizing the resonance enhancement of the ν(Fe=O) mode upon excitation of these chromophores. © 2008 American Chemical Society.
DOI
10.1021/ja8022576
Appears in Collections:
자연과학대학 > 화학·나노과학전공 > Journal papers
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE