Magneto-Structural Correlation Studies of A Ferromagnetically Coupled Dinuclear Vanadium(IV) Complex. Single-Crystal EPR Study
详细信息 查看全文
- 作者：Murugesan Velayutham ; Babu Varghese ; and Sankaran Subramanian
- 刊名：Inorganic Chemistry
- 出版年：1998
- 出版时间：March 23, 1998
- 年：1998
- 卷：37
- 期：6
- 页码：1336 - 1340
- 全文大小：71K
- 年卷期：v.37,no.6(March 23, 1998)
- ISSN：1520-510X
文摘
The dimer potassiumdioxo(citrato)vanadate(IV)-6-water,K4{VO[O2CCH2C(O)(CO2)CH2CO2]}2·6H2O,wasprepared by the reaction of citric acid and metavanadate in a neutralsolution. The complex crystallizes in thespace group P
with unit cell parameters a= 8.474(5) Å, b = 8.902(7) Å, c= 9.596(9) Å, 
= 71.50(6)
, 
=70.81(9), 
= 87.45(2), V = 647.1Å3, and Z = 1. The dimeric anioncontains a centrosymmetric planarfour-membered V2O2 ring with the bridgingoxygens derived from the hydroxyl groups. The configurationofthe anion is anti-coplanar. A frozen solution EPRspectrum with zero-field splitting and 15 line hyperfinepatternson the parallel and perpendicular features characteristic of twoequivalent vanadium atoms confirms the presenceof a spin triplet. This is further supported by the presence ofhalf-field "forbidden transition" at g 
4. Abroadline with half-field forbidden transitions in the powder EPR spectra atX,Q-bands of the neat sample and atdifferent temperatures shows the presence of a spin triplet groundstate and a very weak intermolecular dipolarinteraction. From anisotropic exchange contributions to D themagnitude of the derived exchange integralJ xy,x2-y2is 56 cm-1. UV-visible, ESCA, andtheoretical BVS studies support the proposed molecular andelectronicstructure of the complex.
with unit cell parameters a= 8.474(5) Å, b = 8.902(7) Å, c= 9.596(9) Å, = 71.50(6), =70.81(9), = 87.45(2), V = 647.1Å3, and Z = 1. The dimeric anioncontains a centrosymmetric planarfour-membered V2O2 ring with the bridgingoxygens derived from the hydroxyl groups. The configurationofthe anion is anti-coplanar. A frozen solution EPRspectrum with zero-field splitting and 15 line hyperfinepatternson the parallel and perpendicular features characteristic of twoequivalent vanadium atoms confirms the presenceof a spin triplet. This is further supported by the presence ofhalf-field "forbidden transition" at g 4. Abroadline with half-field forbidden transitions in the powder EPR spectra atX,Q-bands of the neat sample and atdifferent temperatures shows the presence of a spin triplet groundstate and a very weak intermolecular dipolarinteraction. From anisotropic exchange contributions to D themagnitude of the derived exchange integral