Structure and Magnetic Properties of a Non-Heme Diiron Complex Singly Bridged by a Hydroxo Group
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- 作者：Josseline Jullien ; Gergely Juhá ; sz ; Pierre Mialane ; Eddy Dumas ; Cé ; dric R. Mayer ; Jé ; rô ; me Marrot ; Eric Riviè ; re ; Emile L. Bominaar ; Eckard Mü ; nck ; Francis Sé ; che
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：August 21, 2006
- 年：2006
- 卷：45
- 期：17
- 页码：6922 - 6927
- 全文大小：97K
- 年卷期：v.45,no.17(August 21, 2006)
- ISSN：1520-510X
文摘
The synthesis of the first singly bridged non-heme diiron complex with a 
-hydroxo bridging ligand, [{(salten)Fe}2(OH)][B(C6H5)4]·(CH3CN)x·(H2O)y (1) [H2salten = 4-azaheptane-1,7-bis(salicylideneiminate)], is reported. The complexhas been characterized with X-ray crystallography, FTIR, magnetic susceptibility measurements, and Mössbauerspectroscopy. The data have been compared with the results of DFT calculations on both 1 and a model with anunsupported -oxo bridge (2) to verify the formulation of the complex as a -hydroxo-bridged species. The X-raystructure [Fe-O(H) = 1.997(1) Å and Fe-O(H)-Fe = 159
] is consistent with the DFT-optimized geometry of 1[Fe-O(H) = 2.02 Å and Fe-O(H)-Fe = 151]; the Fe-O(H) distance in 1 is about 0.2 Å longer than the Fe-Oseparations in the optimized geometry of 2 (1.84 Å) and in the crystallographic structures of diiron(III) compoundswith unsupported -oxo bridges (1.77-1.81 Å). The formulation of 1 as a hydroxo-bridged compound is also supportedby the presence of an O-H stretch band in the FTIR spectrum of the complex. The magnetic susceptibilitymeasurements of 1 reveal antiferromagnetic exchange (J = 42 cm-1 and Hex = JS1·S2). Nearly the same J valueis obtained by analyzing the temperature dependence of the Mössbauer spectra (J = 43 cm-1; other parameters:
= 0.49 mm s-1, 
EQ = -0.97 mm s-1, and 
= 0.45 at 4.2 K). The experimental J values and Mössbauerparameters agree very well with those obtained from DFT calculations for the -hydroxo-bridged compound (J =46 cm-1, = 0.48 mm s-1, EQ = -1.09 mm s-1, and = 0.35). The exchange coupling constant in 1 isdistinctly different from the value J 
200 cm-1 calculated for the optimized -oxo-bridged species, 2. The increasedexchange-coupling in 2 arises primarily from a decrease in the Fe-O bond length.
-hydroxo bridging ligand, [{(salten)Fe}2(OH)][B(C6H5)4]·(CH3CN)x·(H2O)y (1) [H2salten = 4-azaheptane-1,7-bis(salicylideneiminate)], is reported. The complexhas been characterized with X-ray crystallography, FTIR, magnetic susceptibility measurements, and Mössbauerspectroscopy. The data have been compared with the results of DFT calculations on both 1 and a model with anunsupported -oxo bridge (2) to verify the formulation of the complex as a -hydroxo-bridged species. The X-raystructure [Fe-O(H) = 1.997(1) Å and Fe-O(H)-Fe = 159] is consistent with the DFT-optimized geometry of 1[Fe-O(H) = 2.02 Å and Fe-O(H)-Fe = 151]; the Fe-O(H) distance in 1 is about 0.2 Å longer than the Fe-Oseparations in the optimized geometry of 2 (1.84 Å) and in the crystallographic structures of diiron(III) compoundswith unsupported -oxo bridges (1.77-1.81 Å). The formulation of 1 as a hydroxo-bridged compound is also supportedby the presence of an O-H stretch band in the FTIR spectrum of the complex. The magnetic susceptibilitymeasurements of 1 reveal antiferromagnetic exchange (J = 42 cm-1 and Hex = JS1·S2). Nearly the same J valueis obtained by analyzing the temperature dependence of the Mössbauer spectra (J = 43 cm-1; other parameters: = 0.49 mm s-1, EQ = -0.97 mm s-1, and = 0.45 at 4.2 K). The experimental J values and Mössbauerparameters agree very well with those obtained from DFT calculations for the -hydroxo-bridged compound (J =46 cm-1, = 0.48 mm s-1, EQ = -1.09 mm s-1, and = 0.35). The exchange coupling constant in 1 isdistinctly different from the value J 200 cm-1 calculated for the optimized -oxo-bridged species, 2. The increasedexchange-coupling in 2 arises primarily from a decrease in the Fe-O bond length.