Functional (Supra)Molecular Nanostructures - ruben-group

Habilitation Dr. Mario Ruben
ULP Strasbourg
Figure 5. Top and side view of the x-ray single crystal structure of the metal ion array
[Fe II 4B4] 8+ (2) (anions, solvent molecules, hydrogen atoms and the rotational disorder of the
pyridine groups are omitted for clarity).
The generation of the second order coordination hierarchy was achieved by layering of
an acetonitrile solution of of the tetranuclear unit [Fe II 4A4] 8+ (1) (as its ClO4 salt) with a six-
fold excess of a La(ClO4)3 in methanol resulting in deep-green, triangular-shaped crystals of
supramolecular assembly product 3. Elemental analysis of these crystals point to a {-
[Fe II 4A4]-(La III )}(ClO4)11 composition with additional sixteen water and two acetonitrile
molecules. Single crystal X-ray investigations reveal a one-dimensional pillar-like motive
involving aligned alternating [Fe II 4(A)4] 8+ and La 3+ units (apparently interconnecting the
tetranuclear Fe4 II units in a linear fashion by the mediating coordination of one La 3+ ion to two
four-fold sets of 3-pyridyl groups above and below the molecular plan of the units).
Unfortunately, due to the bad quality of the crystals, the resulting elevated R-factor of the data
set prevent from a more detailed discussion of the molecular crystal structure of {[Fe II 4A4]-
(La III )4}n 11+ (3) (Figure 6).
To achieve a second order assembly of grid-like modules [Fe II 4B4] 8+ (2), a solution of
its BF4 - -salt in acetonitrile was layered with a solution of methanol containing six equivalents
of AgBF4. After several weeks, pine-green prisms of compound 4 had grown at the diffusion
interface of the two solutions. Single crystal X-ray diffraction studies at 120 K revealed that
in compound 4 all eight exo-4-pyridyl groups of each [Fe II 4B4] 8+ unit were coordinated to Ag I
ions (Figure 7).
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