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@PHDTHESIS{Sturm:854946,
author = {Sturm, Lisa},
othercontributors = {Oppel, Iris Marga and Albrecht, Markus},
title = {{E}influss von {P}seudohalogeniden und {C}arboxylaten auf
die {K}omplexierung zweiwertiger {M}etallionen durch
{T}ris(2-pyridinylen-{N}-oxid)triaminoguanidin},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-09881},
pages = {1 Online-Ressource : Illustrationen},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2022},
abstract = {C3-symmetric triaminoguanidine based ligands are
established as triangular building blocks in supramolecular
compounds like polymers or discrete monomers, dimers, and
polyhedra. The reaction of
tris(2-pyridinylene-N-oxide)triaminoguanidine with zinc(II)
carboxylates in presence of (pseudo)halides results in
protein-sized metallocycles consisting of twelve ligands
linked by octahedrally coordinated zinc(II) centers. Besides
crystals of the metallocycles, the crystallization of
carboxylate-bridged coordination di/polymers is observed in
the same reaction vessel. To address this issue, the
influence of the solvent, the chain length of the
carboxylate, the co-ligands and their stoichiometry is
investigated, while other factors are kept as constant as
possible. In this way, a sensitive dependence of the binding
motif on the stoichiometric pseudohalide-carboxylate ratio
was revealed. Small or no amounts of pseudohalide combined
with sufficient equivalents of carboxylate lead to the
formation of carboxylate-bridged di/polymers. Increasing the
pseudohalide stoichiometry results in the crystallization of
mixed compounds and finally of metallocycles. By adjusting
the co-ligand stoichiometry, crystallization of a desired
compound can be predicted and selectively induced. Applying
this principle to the chemically related cadmium(II) yields
in a series of carboxylate-bridged di/polymers, whereas the
addition of thiocyanate gives a cadmium(II)-bridged
structure, which can be considered as metallocycle fragment.
Cadmium(II) prefers coordination numbers of six and higher
due to its ionic radius, which inhibits the formation of a
metallocycle. Cobalt(II) ions instead built up polymers and
metallocycles showing the same co-ligand dependence as
zinc(II). Magnetic measurements revealed predominantly
antiferromagnetic behavior of these compounds due to short
Co(II)-Co(II) distances. In heterometallic metallocycles,
zinc(II) ions may isolate the cobalt(II) centers, which
could probably result in very large discrete molecules with
interesting magnetic properties.},
cin = {151520 / 150000},
ddc = {540},
cid = {$I:(DE-82)151520_20140620$ / $I:(DE-82)150000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-09881},
url = {https://publications.rwth-aachen.de/record/854946},
}
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