engleski

Homo- and heteropolynuclear compounds obtained using [MIII(C2O4)3]3− (MIII = Cr or Fe) as building blocks and alkyl-substituted amines

Multifunctional properties of the coordination polymers can often be achieved by combining the intrinsic properties of the host, especially the magnetic ones, with an additional functionalities coming from the selected guest molecules [1]. The oxalate group, C2O42, has been demonstrated to be one of the most versatile ligands used in the preparation of these systems. Due to its various coordination modes towards the metal centres as well as its ability to mediate magnetic interactions between paramagnetic metal ions, a large number of oxalate-based transition-metal species of different nuclearity, connectivity and dimensionality have been synthesized and characterized, many of them having tunable magnetic frameworks [2]. Since their discovery, homo- and heterometallic 2D and 3D oxalate-based extended networks of a general formula [MaII/IIIMbI/II(C2O4)]n2n–/n–, obtained from a combination of tris(oxalate)metalates, [MIII(C2O4)3]3–, with other metallic ions, using different template cations, have attracted a lot of attention. The anionic networks provide magnetic properties (ferro-, antiferro-, or ferrimagnetic ordering) depending on the nature of the connected metal ions. Furthermore, these reported polymers are mostly negatively charged and therefore can be combined with different (functional) molecular cations in order to afford salts combining cooperative magnetism with a second property of interest hence forming multifunctional materials. Recently published oxalate-based networks have shown high humidity-dependent proton conductivity related to the presence of substituted ammonium and/or crystallization water which form hydrophilic layers that enabled conductive pathways of protons [2, 3]. To achieve our final goal – the development of materials containing noteworthy structural, magnetic and/or electrical features, novel homo- and heteropolynuclear oxalate-based systems have been synthesized using tris(oxalato)metalates, [MIII(C2O4)3]3– (MIII = Cr or Fe), as ligands towards second transition metal ion (MnII or CuII) and N, N-diethylmethylamine or N, N- dimethylethylamine. In addition to the single crystal X-ray diffraction study, characterization of the new complexes has been accomplished by means of the IR spectroscopy and thermal analysis.

coordination polymers ; oxalate complex ; proton ; conductivity

nije evidentirano