A new twist on an old ligand: a [Mn] double square wheel and a [Mn] contorted wheel
Ligand design remains key to the synthesis of coordination compounds possessing specific topologies, nuclearities and symmetries that direct targeted physical properties. N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal...
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Veröffentlicht in: | Inorganic chemistry frontiers 2021-04, Vol.8 (7), p.184-189 |
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Sprache: | eng |
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Zusammenfassung: | Ligand design remains key to the synthesis of coordination compounds possessing specific topologies, nuclearities and symmetries that direct targeted physical properties. N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal complexes with fascinating magnetic properties. Here, we show that combining three ethanolamine moieties within the same organic framework in the form of the pro-ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (LH
3
) leads to the formation of two highly unusual Mn wheels. Reaction of Mn(NO
3
)
2
·6H
2
O with LH
3
in basic methanolic solutions leads to the formation of [Mn
III
12
Mn
II
4
(μ
3
-O)
6
(μ-OH)
4
(μ
3
-OMe)
2
(μ-OMe)
2
(L)
4
(LH)
2
(H
2
O)
10
](NO
3
)
6
(OH)
2
(
1
) and [Mn
III
10
(μ
3
-O)
4
(μ-OH)
4
(μ-OMe)
4
(L)
4
(H
2
O)
4
](NO
3
)
2
(
2
), the only difference in the synthesis being the ratio of metal:ligand employed. The structure of the former describes two offset [Mn
III
6
Mn
II
2
] square wheels, linked through a common centre, and the latter a single [Mn
III
10
] wheel twisted at its centre, such that the top half is orientated perpendicular to the bottom half. In both cases the L
3−
/LH
2−
ligands dictate the orientation of the Jahn-Teller axes of the Mn
III
ions which lie perpendicular to the triazacyclohexane plane. Direct current magnetic susceptibility and magnetisation data reveal the presence of competing exchange interactions in
1
and strong antiferromagnetic interactions in
2
. Given the simplicity of the reactions employed and the paucity of previous work, the formation of these two compounds suggests that LH
3
will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal complexes.
The use of 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (LH
3
) in manganese cluster chemistry leads to the synthesis of a {Mn
16
} double square wheel and a {Mn
10
} contorted wheel. |
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ISSN: | 2052-1553 2052-1545 2052-1553 |
DOI: | 10.1039/d0qi01495h |