Proof of Large Positive Zero-Field Splitting in a Ru25+ Paddlewheel
详细信息 查看全文
- 作者：Wei-Zhong Chen ; F. Albert Cotton ; Naresh S. Dalal ; Carlos A. Murillo ; Chris M. Ramsey ; Tong Ren ; and Xiaoping Wang
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：September 14, 2005
- 年：2005
- 卷：127
- 期：36
- 页码：12691 - 12696
- 全文大小：137K
- 年卷期：v.127,no.36(September 14, 2005)
- ISSN：1520-5126
文摘
We present the synthesis, as well as the structural and magnetic characterization, of [Ru2(D(3,5-Cl2Ph)F)4Cl(0.5H2O)]·C6H14 (D(3,5-Cl2Ph)F = N,N'-di(3,5-dichlorophenyl)formamidinate), a Ru25+ compoundhaving a 4B2u ground state derived from a 
chars/sigma.gif" BORDER=0 >2chars/pi.gif" BORDER=0 >4chars/delta.gif" BORDER=0 >2chars/pi.gif" BORDER=0 >*2chars/delta.gif" BORDER=0 >* electron configuration. The persistence of thisconfiguration from 27 to 300 K is shown by the invariance of the Ru-Ru distance. Orientation-dependentmagnetic susceptibility (chars/chi.gif" BORDER=0 >T) and magnetization (M(H)) data are in accord with a spin quartet ground statewith large magnetocrystalline anisotropy associated with a large axial zero-field splitting (D) parameter.Theoretical fits to chars/chi.gif" BORDER=0 >T and M(H) plots yielded D/kB = +114 K, implying an S = ±1/2 Kramers doublet groundstate at low temperature. Single-crystal and powder EPR data are consistent with this result, as the onlyobserved transition is between the Ms = ±1/2 Zeeman levels. The g values are g
= 2.182, g
= 1.970, andD = 79.8 cm-1. The totality of the results demands D 
0.
chars/sigma.gif" BORDER=0 >2chars/pi.gif" BORDER=0 >4chars/delta.gif" BORDER=0 >2chars/pi.gif" BORDER=0 >*2chars/delta.gif" BORDER=0 >* electron configuration. The persistence of thisconfiguration from 27 to 300 K is shown by the invariance of the Ru-Ru distance. Orientation-dependentmagnetic susceptibility (chars/chi.gif" BORDER=0 >T) and magnetization (M(H)) data are in accord with a spin quartet ground statewith large magnetocrystalline anisotropy associated with a large axial zero-field splitting (D) parameter.Theoretical fits to chars/chi.gif" BORDER=0 >T and M(H) plots yielded D/kB = +114 K, implying an S = ±1/2 Kramers doublet groundstate at low temperature. Single-crystal and powder EPR data are consistent with this result, as the onlyobserved transition is between the Ms = ±1/2 Zeeman levels. The g values are g = 2.182, g = 1.970, andD = 79.8 cm-1. The totality of the results demands D 0.