A Distorted Cubic Tetranuclear Copper(II) Phosphonate Cage with a Double-Four-Ring-Type Core

Abstract

The reaction of Cu2(O2CMe)(4).2H2O with tert-butylphosphonic acid and 3,5-di-tert-butylpyrazole in the presence of triethylamine leads to a high-yield synthesis of the tetranuclear compound [Cu2(3,5-t-Bu2PzH)2(t-BuPO3)2]2 (1). The latter has a distorted cubic cage structure and its core resembles the D4R (double-four-ring) motif found in zeolites. The phosphonate, [t-BuPO3]2-, functions as a dianionic tridentate ligand, while the pyrazole ligands are neutral and are monodentate. The coordination geometry at each copper atom is distorted square planar with a 3O,1N coordination environment. Magnetic measurements on 1 reveal that the chiT product continuously decreases to reach a value very close to zero at 1.8 K, indicating dominant antiferromagnetic interactions between Cu(II) ions that leads to an S=0 ground state. The tetranuclear cage 1 functions as a very effective artificial nuclease in the presence of an external oxidant, magnesium monoperoxyphthalate.

Molecular Metal Phosphonates

“…Similar types of cage structures of main-group as well as transition metals phosphonates are known, as discussed above. 35,45,68,70,74,85,146,218,220 A This compound contains four Co II ions, two [HPMIDA] − , and two [PMIDA] 2− ligands. 245 The four Co II ions lie in a plane and are bound by tetradentate chelating PMIDA, along with two HPMIDA ligands ( Figure 107).…”

Coordination Versatility of Pyrazole‐Based Ligands towards High‐Nuclearity Transition‐Metal and Rare‐Earth Clusters

“…[95] The compound has an unusual stability due to the [Fe 4 O 4 ] 4+ core. [100] Chandrasekhar and co-workers have employed the combination of phosphonates and pyrazoles (HL1a, HL1k, HL1l and HL1m) as ligands to form a tetranuclear cadmium(II) compound [101] and copper(II) complexes of different nuclearities, [102][103][104][105] ranging from tetranuclear to hexadecanuclear ( Figure 8). [96] These compounds exhibit similar redox properties, demonstrating that the [Fe 4 O 4 ] 4+ core is redox-active.…”

Engineering Solid‐State Molecular Switches: N‐Salicylidene N‐Heterocycle Derivatives

“…[13] This diversity of interactions explains the complexity of supramolecules which can be either artificial (nanogrids, [14][15][16] nanoracks, [17] nanocages [18] ) or natural [19] (DNA, recognition proteins). Supramolecular interactions can be very stable (thermodynamic) or very labile (kinetic), [20] which allows the system to (re)organize either itself [21] or under a given constraint (temperature, [21] light irradiation, [10,22] pH [23] and solvent change, [21] concentration [21] ) to form complex self-assemblies.…”