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Dinuclear copper() complexes containing oxamate and blocking ligands: crystal structure, magnetic properties, and DFT calculations
Ist Teil von
New journal of chemistry, 2020-02, Vol.44 (6), p.2597-268
Ort / Verlag
Cambridge: Royal Society of Chemistry
Erscheinungsjahr
2020
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Three dinuclear copper(
ii
) complexes containing oxamate-based ligands with the chemical formula [Cu(
o
pba)Cu(dap)(H
2
O)]·H
2
O (
1
), [Cu(
o
pba)Cu(dap-OH)(H
2
O)]·1.5H
2
O (
2
), and [Cu(
o
pba)Cu(en)(H
2
O)]·4H
2
O (
3
) in which
o
pba =
o
-phenylenebis(oxamato), dap = 1,3-diaminopropane, dap-OH = 2-hydroxy-1,3-diaminopropane and en = ethylenediamine have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction. The molecular structures of
1-3
consist of neutral dicopper(
ii
) complexes obtained by the "complex as a ligand" strategy, in which each [Cu(
o
pba)]
2−
fragment acts as a bidentate ligand towards the copper(
ii
) ion bonded to the amine capping ligands (dap, dap-OH and en) and the two other carbonyl groups are uncoordinated. Variable-temperature magnetic susceptibility measurements of
1-3
in the temperature range of 4-300 K reveal a strong antiferromagnetic coupling between the metal centers through the oxamate bridge with
J
= −183.5 cm
−1
(
1
),
J
= −195.8 cm
−1
(
2
), and
J
= −195.6 cm
−1
(
3
). The fit of the variable-temperature magnetic susceptibility data of
3
revealed that Cu
II
Cu
II
Cu
II
Cu
II
coupling between the dinuclear entities is very weak. In all cases, the Hamiltonian used was
H
=
−JS
1
·
S
2
. DFT calculations based on the broken-symmetry formalism were used to provide further insight and an explanation for the reported behavior.
Dicopper(
ii
) complexes were prepared as promising platforms for the design of polynuclear systems providing an avenue toward new molecule-based materials.