Building-up host-guest helicate motifs and chains: a magneto-structural study of new field-induced cobalt-based single-ion magnets

In this work, we present the synthetic pathway, a refined structural description, complete solid-state characterization and the magnetic properties of four new cobalt(ii) compounds of formulas [Co(H₂O)₆][Co₂(H₂mpba)₃]·2H₂O·0.5dmso (1), [Co(H₂O)₆][Co₂(H₂mpba)₃]·3H₂O·0.5dpss (2), [Co₂(H₂mpba)₂(H₂O)₄]_n·4nH₂O (3), and [Co₂(H₂mpba)₂(CH₃OH)₂(H₂O)₂]_n·0.5nH₂O·2ndpss (4) [dpss = 2,2'-dipyridyldisulfide and H₄mpba = 1,3-phenylenebis(oxamic) acid], where 2 and 4 were obtained from [Co(dpss)Cl₂] (Pre-I) as the source of cobalt(ii). All four compounds are air-stable and were prepared under ambient conditions. 1 and 2 were obtained from a slow diffusion method [cobalt(ii) : H₂mpba^2- molar ratio used 1 : 1] and their structures are made up of [Co₂(H₂mpba)₃]^2- anionic helicate units and [Co(H₂O)₆]²⁺ cations, exhibiting supramolecular three-dimensional structures. Interestingly, a supramolecular honeycomb network between the helicate units interacting with each other through R₂²(10) type hydrogen bonds occurs in 2 hosting one co-crystallized dpss molecule. On the other hand, for the first time, linear (3) and zigzag (4) cobalt(ii) chains were isolated by slow evaporation of stirred solutions of mixed solvents with cobalt(ii) : H₂mpba^2- in 1 : 2 molar ratio at room temperature. Magnetic measurements of Pre-I revealed a quasi magnetically isolated S = 3/2 spin state with a significant second-order spin-orbit contribution as expected for tetrahedrally coordinated cobalt(ii) ions. The analysis of the variable temperature static (dc) magnetic susceptibility data through first- (1 and 3) and second-order spin-orbit coupling models (2 and 4) reveals the presence of magnetically non-interacting high-spin cobalt(ii) ions with easy-axis (1 and 4)/easy-plane magnetic anisotropies (2 and 4) with low rhombic distortions. Dynamic (ac) magnetic measurements for Pre-I and 1-4 below 8.0 K show that they are examples of field-induced Single-Ion Magnets (SIMs).

2D and 3D mixed MII/CuIImetal–organic frameworks (M = Ca and Sr) withN,N′-2,6-pyridinebis(oxamate) and oxalate: preparation and magneto-structural study

Heterobimetallic coordination polymers with either antiferro- of ferromagnetic interactions are described herein.

The first X-ray structure of a silver–nucleotide complex: interaction of ion Ag(i) with cytidine-5′-monophosphate

The synthesis and X-ray characterization of an unprecedented complex of Ag(i) with cytidine-5′-monophosphate (HCMP) is reported. The coordination of Ag(i) to HCMP is via both the N3 and O2 atoms of two cytosine moieties and the phosphate group, generating a MOF.

Homochiral self-assembly of biocoordination polymers: anion-triggered helicity and absolute configuration inversion

The different natures of the weakly coordinating anions - triflate or perchlorate - in the Cu2+-mediated self-assembly of cytidine monophosphate nucleotide play a fundamental role in the homochiral resolution process, yielding one-dimensional copper(ii) coordination polymers of opposite helicity that can be easily inverted, in a reversible way, by changing the nature of the anion as revealed by circular dichroism experiments both in solution and in the solid state.

A heterobimetallic [MnII5CuII5] nanowheel modulated by a flexible bis-oxamate type ligand

The reaction of the dicopper(ii) metallacyclophane [Cu₂(edpba)₂]²⁻ with fully solvated manganese(ii) ions yields the nanowheel [Mn₅Cu₅(edpba)₅] with a S = 10 low-lying spin state.

The chloridomolybdenum(III) cluster in [BMIm]4[AgMo10Cl35] with infinite chains of Ag(+)-linked [Mo10Cl35](5-) wheels

[BMIm]4[AgMo10Cl35] is prepared by reaction of MoCl5 and elemental silver in the ionic liquid [BMIm][AlCl4] ([BMIm(+)]: 1-butyl-4-methylimidazolium). Surprisingly, elemental silver is oxidized under these conditions. The title compound contains a new wheel-shaped [Mo10Cl35](5-) chlorido molybdenum(iii) species with five pairs of Mo-Mo bonds. The Mo-Mo distances are found to be 263 pm on average. The [Mo10Cl35](5-) wheels exhibit a maximum opening of 558 pm in diameter. They are interlinked via Ag(+) to form infinite [AgMo10Cl35](4-) chains. The title compound is characterized by single crystal structure analysis, EDX, FT-IR and UV-Vis spectroscopy. The wheel-type structure and Ag(+) linkage to infinite chains are a new aspect of halogenido metalates and low-valence molybdenum compounds.

Oxamato-based coordination polymers: recent advances in multifunctional magnetic materials

The design and synthesis of novel examples of multifunctional magnetic materials based on the so-called coordination polymers (CPs) have become very attractive for chemists and physicists due to their potential applications in nanoscience and nanotechnology.

Hexagonal molecular "palladawheel"

A hexagonal molecular "palladawheel" consisting of six N,N'-diphenyl-2,6-pyridinedicarboxamide-Pd(II) pincer complexes held together via six Pd∙∙∙O=CAmide bonds was efficiently synthesized and crystallographically characterized. The hexameric ring possesses C3 (pseudo-S6) symmetry with up-down alternating phenyl substituents acting as interior "spokes" and exterior "propellers."