We present the synthesis, as well as the stru
ctural and magneti
c chara
cterization, of [Ru
2(D(3,5-Cl
2Ph)F)
4Cl(0.5H
2O)]·C
6H
14 (D(3,5-Cl
2Ph)F =
N,
N'-di(3,5-di
chlorophenyl)formamidinate), a Ru
25+ compoundhaving a
4B
2u ground state derived from a
![](/images/gif<font color=)
chars/sigma.gif" BORDER=0 >
2![](/images/gif<font color=)
chars/pi.gif" BORDER=0 >
4![](/images/gif<font color=)
chars/delta.gif" BORDER=0 >
2![](/images/gif<font color=)
chars/pi.gif" BORDER=0 >*
2![](/images/gif<font color=)
chars/delta.gif" BORDER=0 >* ele
ctron
configuration. The persisten
ce of this
configuration from 27 to 300 K is shown by the invarian
ce of the Ru-Ru distan
ce. Orientation-dependentmagneti
c sus
ceptibility (
![](/images/gif<font color=)
chars/
chi.gif" BORDER=0 >
T) and magnetization (
M(
H)) data are in a
ccord with a spin quartet ground statewith large magneto
crystalline anisotropy asso
ciated with a large axial zero-field splitting (
D) pa
rameter.Theoreti
cal fits to
![](/images/gif<font color=)
chars/
chi.gif" BORDER=0 >
T and
M(
H) plots yielded
D/
kB = +114 K, implying an
S = ±
1/
2 K
ramers 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![](/images/entities/bottom.gif)
= 2.182,
g![](/images/entities/par.gif)
= 1.970, and
D = 79.8
cm
-1. The totality of the results demands D
![](/images/entities/Gt.gif)
0.