Spectroscopic, Magnetochemical, and Crystallographic Study of Cesium Iron Phosphate Hexahydrate: Characterization of the Electronic Structure of the Iron(II) Hexa-aqua Cation in a Quasicubic Environme
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- 作者：Graham Carver ; Christopher Dobe ; Thomas B. Jensen ; Philip L. W. Tregenna-Piggott ; Stefan Janssen ; Eckhard Bill ; Garry J. McIntyre ; and Anne-Laure Barra
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：June 12, 2006
- 年：2006
- 卷：45
- 期：12
- 页码：4695 - 4705
- 全文大小：273K
- 年卷期：v.45,no.12(June 12, 2006)
- ISSN：1520-510X
文摘
Spectroscopic, magnetochemical, and crystallographic data are presented for CsFe(H2O)6PO4, a member of alittle-known isomorphous series of salts that facilitates the study of hexa-aqua ions in a quasicubic environment.Above 120 K, the deviations from cubic symmetry are minimal, as shown by the first example of an iron(II) Mössbauerspectrum that exhibits no measurable quadrupole splitting. Two crystallographically distinct [Fe(OH2)6]2+ complexesare identified from inelastic neutron-scattering (INS) experiments conducted between 2 and 15 K. The data aremodeled with the ligand-field Hamiltonian, 
mages/entities/Hcirc.gif"> = mages/gifchars/lambda.gif" BORDER=0 >mages/entities/Lcirc.gif">mages/entities/Scirc.gif"> + mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">B(kmages/entities/Lcirc.gif"> + 2mages/entities/Scirc.gif">) + mages/gifchars/Delta.gif" BORDER=0 >tet{mages/entities/Lcirc.gif">z2 - (1/3)L(L + 1)} + mages/gifchars/Delta.gif" BORDER=0 >rhom{mages/entities/Lcirc.gif">x2 - mages/entities/Lcirc.gif">y2},operating in the ground-term 5T2g (Oh) basis. An excellent reproduction of INS, Mössbauer, HF-EPR, andmagnetochemical data are obtained in the 2 and 15 K temperature regimes with the following parameters: mages/gifchars/lambda.gif" BORDER=0 > =-80 cm-1; k = 0.8; site A mages/gifchars/Delta.gif" BORDER=0 >tet = 183 cm-1, mages/gifchars/Delta.gif" BORDER=0 >rhom= 19 cm-1; site B mages/gifchars/Delta.gif" BORDER=0 >tet = 181 cm-1, mages/gifchars/Delta.gif" BORDER=0 >rhom= 12 cm-1. Thecorresponding zero-field-splitting (ZFS) parameters of the conventional S = 2 spin Hamiltonian are as follows: siteA D = 12.02 cm-1, E = 2.123 cm-1; site B D = 12.15 cm-1, E = 1.37 cm-1. A theoretical analysis of thevariation of the energies of the low-lying states with respect to displacements along selected normal coordinatesof the [Fe(OH2)6]2+, shows the zero-field splitting to be extremely sensitive to small structural perturbations of thecomplex. The expressions derived are discussed in the context of spin-Hamiltonian parameters reported for the[Fe(OH2)6]2+ cation in different crystalline environments.