1. Z. Leśnikowski, E. Przelazły, K. Dziedzic-Kocurek, J. Stanek
Intramolecular rotations of ferra(III) bis(dicarbollide) ion studied by 57Fe nuclear probe
Z. Leśnikowski, E. Przelazły, K. Dziedzic-Kocurek, J. Stanek
Mössbauer spectrum
Properties of Fe(C2B9H11)2 : iron point of view.
a) Local electronic states of Fe in Fe(C2B9H11)2 (Fesan) and in
Fe(C2B9H11)2-[O(CH2CH2)2O] (Fesan-dioksan)
b) Dynamical states - rotary motion
3. Metallacarboranes as potencial sensor of effective dose
Cracow, Sept. 14, 2-18

2. Mössbauer spectrum [mm/s] Valence states Fe magnetic moments Dynamics
Intensity of the transmitted
 - radiation
[mm/s]
Energy of =radiation in mm/s. (ΔE/E=v/c). 1mm/s =48 neV = 77*10-28 J = cm-1
Valence states
Fe magnetic moments
Dynamics
Nuclear level scheme of 57Fe in different local states

3. A Family of Octahedral Magnetic Molecules Based on [NbIV(CN)8]4−
Current example:
Inorganic Chemistry, 2017,
A Family of Octahedral Magnetic Molecules Based on [NbIV(CN)8]4− IS QS

4. „Fesan” Fe(C2B9H11)2 ferra(III) bis(dicarbollide)
Low symmetry of the Fe site generates electric field gradient :
quadrupole splitting is expected.

5. Mössbauer results IS(Fesan) =0.17 mm/s Fe3+ LS D = 580 K D = 189 K
0.16
IS(Fesan) =0.17 mm/s
Fe3+ LS

6. Interesting result:

7. Electrical or Photocontrol of the Rotary Motion of a Metallacarborane
M. Frederick Hawthorne, Jeffrey I. Zink, Johnny M. Skelton,Michael J. Bayer Chris Liu,Ester Livshits, Roi Baer, DanielNeuhauser1
Science 2004.

8. May be (C2B9H11) rotate spontaneosly ?
Facts:
1.The 57Fe Mössbauer spectroscopy has its characteristic observation time,  = 141 ns, the life time of the excited 14.4 keV nuclear state.
2. Iron is coordinated by 2 pairs of carbon atoms which may form three different configurations, cisoid, gauche and transoid; in each configuration 57Fe experiences slightly different electric field gradient which produces different quadrupole splitting of the spectrum.
3. If the sample is composed of such stable configurations, the spectrum should be composed of three (overlapping) quadrupole doublets, in the entire investigated temperature range.
5. In case of fast rotation, with period comparable with the observation time, the spectrum should be significantly alternated due to the coherency of the absorption process.

9. Fourier transformation Tuning forks
Method of simulation
At LN2 temperature the most energetically favorable configuration is occupied.
At higher temperature the C2B9H11 ligands start to rotate along Fe axis, which causes the oscillations of electric field gradient at 57Fe nuclei oscillates around the low temperature value, the magnitude of this oscillation was adjusted experimentally.
3. The method of the simulation was inspired by a literature approach, where the dynamically induced temperature dependence of quadrupole splitting in oxymyoglobin was explained.
4. The simulation was performed for frequencies of rotation, n, in units of -1, between n=0.01 and 100.
Clasical analog
frequency
rambling
Fourier transformation
Tuning forks

10. simulation
n=0.01
n=1
n=100
experiment

11. Experimental and theoretical line broadening
W(T)
W(n)
At 210 K n=1 (one rotation in 141 ns) f=7*106 Hz
n(T)
ΔEr=16 meV, n0=2.4 (f0=1.7*107 Hz)

12. 8-dioxane ferra(III) bis(dicarbollide) (Fesan – dioksan)
Mössbauer results
Qualitative conclusions:
The attachment of dioxane molecule and formation a positive charge on the oxygen linked to boron atom
does not block the rotation., but modifies its character
does not change the spin and electron density at Fe
modifies (decreases) the electric field gradient at Fe position

13. Perspectives 5 20 Determination of the equivalent dose, H,
wR : coefficients for different radiations
radiation wR
Neutrons, < 10 keV 5
 particles, fission fractions 20
But: n+10B = 4He + 7Li + 
Moreover: electronic and nuclear energy transfer

14. Proposal: Mössbauer studies of Fesan iradiated by neutrons.
Because Fe is sensitive on the local sourondings, it should be possible to determine
from the Mossbauer spectrum fraction of the demaged Fe(C2B9H11)2 molecules due
to the nuclear energy transfer after neutron capture !
Mössbauer spectroscopy is sensitive for
the structural radiation damage.
My youth