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 ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (LH3) leads to
the formation of two highly unusual Mn wheels. Reaction of Mn(NO3)2·6H2O with LH3 in basic methanolic
solutions leads to the formation of [MnIII
12MnII
4(µ3-O)6(µ-OH)4(µ3-OMe)2(µOMe)2(L)4(LH)2(H2O)10](NO3)6(OH)2 (1) and [MnIII
10(µ3-O)4(µ-OH)4(µ-OMe)4(L)4(H2O)4](NO3)2 (2); the only
difference in the synthesis being the ratio of metal:ligand employed. The structure of the former describes
two offset [MnIII
6MnII
2] square wheels, linked through a common centre, and the latter a single [MnIII
10] wheel
twisted at its centre, such that the top half is orientated perpendicular to the bottom half. In both cases the
L
3-
/LH2-
ligands dictate the orientation of the Jahn-Teller axes of the MnIII 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 LH3 will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal
complexes
Rational design of potential spin qubits manipulated by the valence tautomerism mechanism: quantum-chemical modeling of the trinuclear transition metal complexes with bischelate linkers
