Ferromagnetic Exchange Coupling of Vanadium(IV) d Spins across Pyrimidine Rings: Dinuclear Complexes of Oxovanadium(IV) Bis(1,1,1,5,5,5
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- 作者：Takayuki Ishida ; Shin-ichi Mitsubori ; Takashi Nogami ; Naoya Takeda ; Masayasu Ishikawa ; and Hiizu Iwamura
- 刊名：Inorganic Chemistry
- 出版年：2001
- 出版时间：December 31, 2001
- 年：2001
- 卷：40
- 期：27
- 页码：7059 - 7064
- 全文大小：110K
- 年卷期：v.40,no.27(December 31, 2001)
- ISSN：1520-510X
文摘
Dinuclear oxovanadium(IV) complexes bridged by pyrimidine derivatives, L[VO(hfac)2]2 [L = pyrimidine (PM),4-methylpyrimidine (MPM), 4,6-dimethylpyrimidine, 4-aminopyrimidine, and quinazoline; hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate], were synthesized and characterized. All of them showed intramolecularferromagnetic interaction, and the magnetic susceptibilities were analyzed on the basis of the singlet-triplet model,giving 2J/kB = 2.2-5.5 K. PM[VO(hfac)2]2 crystallized in a monoclinic space group C2/c with a = 34.092(2),b = 6.9783(4), and c = 16.4940(9) Å, 
= 109.104(1)
, V = 3707.8(4) Å3, and Z = 4 for C24H8F24N2O10V2, andMPM[VO(hfac)2]2 gave isomorphous crystals. A semiempirical calculation study based on the determined structuresuggests the presence of d
-p interaction between vanadium and pyrimidine nitrogen atoms. Ferromagneticcoupling is explained in terms of a spin-polarization mechanism across the pyrimidine bridge. The intermolecularferromagnetic interaction of PM[VO(hfac)2]2 can be interpreted by the contact between the spin-polarized pyrimidinemoiety and the oxovanadium oxygen atom in an adjacent molecule.
= 109.104(1), V = 3707.8(4) Å3, and Z = 4 for C24H8F24N2O10V2, andMPM[VO(hfac)2]2 gave isomorphous crystals. A semiempirical calculation study based on the determined structuresuggests the presence of d-p interaction between vanadium and pyrimidine nitrogen atoms. Ferromagneticcoupling is explained in terms of a spin-polarization mechanism across the pyrimidine bridge. The intermolecularferromagnetic interaction of PM[VO(hfac)2]2 can be interpreted by the contact between the spin-polarized pyrimidinemoiety and the oxovanadium oxygen atom in an adjacent molecule.