Heterocyclic amine directed synthesis of metal(ii)-oxalates: investigating the magnetic properties of two complete series of chains with S = 5/2 to S = 1/2

Abstract

We report here two series of coordination polymer chains: the first being [M(II)(ox)(bnz)(2)](n) (M = Mn 1, Fe 2, Co 3, Ni 4, Cu 5 and Zn 6; ox = oxalate C(2)O(4)(2-); bnz = benzimidazole) and the second [M(II)(ox)(btz)(2)](n) (M = Mn 7, Fe 8, Co 9, Ni 10, Cu 11 and Zn 12; btz = benzotriazole). The first series displays an unusual homometallic [-M(i)-M(ii)-M(ii)-](n) chain topology and the second series is isostructural to [Fe(II)(ox)(btz)(2)](n), originally reported by Jia et al. (Collect. Czech. Chem. Commun., 2002, 67, 1609-1615). These two series allow us to make comparisons between the spin state of each metal and the magnetic coupling interaction within an isostructural series spanning the full range of spin states available in 3d metals and to investigate which models are the best to use in each case. Compound 8 is a single-chain magnet, the behaviour through spin-canting arising from a Dzyaloshinskii-Moriya interaction. Additionally, we have synthesised a two-dimensional coordination polymer {[Zn(II)(bnz)(4)][Zn(II)(2)(ox)(3)]}(n) (13), in which distorted hexagonal [Zn(II)(2)(ox)(3)](n)(2n-) layers are hydrogen bonded by [Zn(II)(bnz)(4)](2+) cations to give an interlayer separation of 12.001(2) Å.

Crystal structures of isotypic poly[bis(benzimidazolium) [tetra-μ-iodido-stannate(II)]] and poly[bis(5,6-difluorobenzimidazolium) [tetra-μ-iodido-stannate(II)]]

“…In the actual case, however, as a novel aspect, the bicyclic aromatic benzimidazole unit is introduced as an organic part. There are numerous general examples of benzimidazole acting as a neutral ligand (Keene et al, 2010) and similarly in its protonated form (Mouchaham et al, 2010). In this context, the present study explicitly demonstrates that benzimidazolium cations and corresponding derivatives can stabilize the layered perovskite structure as well, while fitting perfectly into the 'footprint' provided by the inorganic framework.…”

Recurrent H-bond graph motifs between metal tris-ethylenediamine cations and uncoordinated oxalate anions: Fitting a three pin plug into a two pin socket

“…The change in solubility is a reflection of the changes in solution speciation, and can result in the formation of new phases containing the amine moiety. 10,11 Dissolving copper(II) oxalate followed by slow evaporation allowed us to obtain crystals of Cu(ox)(en) 2 but have not previously been structurally characterised.…”

Hydrogen-bonding chain and dimer motifs in pyridinium and morpholinium hydrogen oxalate salts

“…Ammonium hydrogen oxalate salts are often useful precursors in the formation of transition metal complexes (Keene et al, 2003) and coordination polymers (Keene et al, 2004). Our research group has an interest in these precursors as part of our investigations into molecular magnets (Keene, et al 2010), not only for their usefulness in this role, but for the complex hydrogen-bonded structures that often arise on crystallization. Previous work from our group has focused on the structure of discrete oxalate dianions and drawn correlations between torsion angles, bond lengths and the crystal packing (Keene et al, 2012).…”