Deprotonation of the fluorenyl‐tethered imidazolinium salt [9‐(C13H9)C2H4N(CH)C2H4N(2,4,6‐Me3C6H2)][BF4] gave a spirocyclic compound that reacted with a synergic mixture of LiPh/LiN(SiMe3)2 or LinBu/LiN(SiMe3)2 to give a dilithium complex incorporating a bridging N(SiMe3)2 ligand. In contrast, deprotonation of the imidazolium salt [9‐(C13H9)C2H4N(CH)C2H2N(Me)][Br] instead yielded the free NHC, which reacted with nBuLi to form a dimeric, NHC‐bridged dilithium complex. Addition of LiN(SiMe3)2 led to coordination and the formation of a dilithium complex with a bridging N(SiMe3)2 ligand, which was characterised in the solid state as a 1D coordination polymer. The reaction of 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr) with lithium indenide and lithium fluorenide gave soluble species with terminal binding of the NHC to the lithium cation and η5 coordination of indenyl or fluorenyl. A symmetrical bridging mode for an NHC donor was therefore observed only if a tethered fluorenyl anion was present with no additional amide ligand.
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...
The methylation of p-tert-butylcalix[4]arene in the distal 1,3-phenolic sites provides the ligand H2L = {p-tert-butylcalix[4](OMe)2(OH)2arene} that enables construction of heteroleptic mononuclear lanthanide complexes. The reaction of (N(nBu)4)(acac) (acac = acetylacetonate),...
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
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