Axial Ligand Effects on the Geometric and Electronic Structures of Nonheme Oxoiron(IV) Complexes.
A series of complexes [Fe[supIV](O)(TMC)(X)+ (where X = 0H, CF[sub3]CO[sub2], N[sub3], NCS, NCO, and CN) were obtained by treatment of the well-characterized nonheme oxoiron(IV) complex [Fe[supIV](O)(TMC)- (NCMe)][sup2+] (TMC = tetramethylcyclam) with the appropriate NR4X salts. Because of the topol...
| Published in: | Journal of the American Chemical Society Vol. 130; no. 37; pp. 12394 - 12408 |
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| Main Authors: | , , , , , , , , , , |
| Format: | Article |
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American Chemical Society
9/17/2008
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| Subjects: | |
| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=34543304&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 34543304 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 9/17/2008 vid: 130 iid: 37 pid: 997 pub: American Chemical Society artinfo: ui: 34543304 10.1021/ja8022576 ppf: 12394 ppct: 14 formats: tig: atl: Axial Ligand Effects on the Geometric and Electronic Structures of Nonheme Oxoiron(IV) Complexes. aug: au: Jackson, Timothy A. Rohde, Jan-Uwe Mi Sook Seo Sastri, Chivukula V. DeHont, Raymond Stubna, Audria Ohta, Takehiro Kitagawa, Teizo Münck, Eckard Nam, Wonwoo Que Jr., Lawrence affil: University of Minnesota Department of Chemistry, University of Kansas, Lawrence, KS 66045 Department of Chemistry, University of Iowa, Iowa City, IA 52242 Ewha Womans University Carnegie Mellon University National Institutes of Natural Sciences su: Ligands (Chemistry) Oxygen Iron Density functionals Electronic structure Complex compounds Extended X-ray absorption fine structure sug: subj: Ligands (Chemistry) Oxygen Iron Density functionals Electronic structure Complex compounds Extended X-ray absorption fine structure ab: A series of complexes [Fe[supIV](O)(TMC)(X)+ (where X = 0H, CF[sub3]CO[sub2], N[sub3], NCS, NCO, and CN) were obtained by treatment of the well-characterized nonheme oxoiron(IV) complex [Fe[supIV](O)(TMC)- (NCMe)][sup2+] (TMC = tetramethylcyclam) with the appropriate NR4X salts. Because of the topology of the TMC macrocycle, the [Fe[supIV](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 Fe[supIV]=O unit, namely, (i) the near- IA 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 [FeW(O)(TMC)(X)]± species have Fe=O bond lengths similar to that of [Fe[supIV](O)(TMC)(NCMe)]2+ (1.66 ± 0.02 A). The mechanisms by which the trans ligands perturb the Fe[sup+=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 л-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[supIV]=O charge-transfer transitions, thereby rationalizing the resonance enhancement of the v(Fe=O) mode upon excitation of these chromophores. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2008 holdings: @attributes: islocal: N |
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