Results and Discussion - New Synthetic Routes to Polyoxometalate Containing Ionic Liquids - page 60

{SiW 11 Ni} with Ni(II)-d 8 is EPR silent as would be expected from a diamagnetic
compound taking the above derived energy diagram (see Figure 30) as basis.

{SiW11Cr} containing Cr(III)-d 3 gives a signal however a very poor one as is often the
case for Cr-containing compounds. The g-values are found to be in the region of 2 and
4.5 allowing at least an unambiguous hint to a d 3 high-spin state.

g-value

76 5 4 3 2

10000 10000

5000 5000

0 0

-5000 -5000

-10000 -10000

100 150 200 250 300 350

magentic field (mT)

Figure 31: EPR-spectrum of (Q 7 ) 5 [ D -SiW 11 O 39 Cr(H 2 O)] obtained in toluene (c = 1 mM) at a temperature of
T = 95 K; radiation frequency f = 8943.7 MHz.

{SiW 11 Mn} contains Mn(II)-d 5 which is isoelectronic to the Fe(III)-based analogue. The
corresponding g-values are found to be in the same region with g = 2.03 and 4.17 also
speaking for a spin S = 3/2 system with above shown energy diagram (see figure 32).
Hyperfine coupling is seen with splitting into 6 lines as expected for 55 Mn (l = 5/2).