NiII formate complexes with bi- and tridentate nitrogen-donor ligands: synthesis, characterization, and magnetic and thermal properties

Karoline Rühlig; Akerke Abylaikhan; Azar Aliabadi; Vladislav Kataev; Simon Liebing; Sebastian Schwalbe; Kai Trepte; Christian Ludt; Jens Kortus; Bernd Büchner; Tobias Rüffer; Heinrich Lang

doi:10.1039/C6DT04556A

Ni^II formate complexes with bi- and tridentate nitrogen-donor ligands: synthesis, characterization, and magnetic and thermal properties†

Karoline Rühlig,^a Akerke Abylaikhan,^a Azar Aliabadi,^b Vladislav Kataev,^b Simon Liebing,^c Sebastian Schwalbe,^c Kai Trepte,^d Christian Ludt,^c Jens Kortus,^c Bernd Büchner,^b Tobias Rüffer

*^a and Heinrich Lang^a

Author affiliations

* Corresponding authors

^a Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz, Germany

^b Leibniz Institute for Solid State and Materials Research IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany

^c TU Bergakademie Freiberg, Institute of Theoretical Physics, Leipziger Strasse 23, 09599 Freiberg, Germany

^d TU Dresden, Theoretical Chemistry, Bergstrasse 66c, 01062 Dresden, Germany

Abstract

The synthesis of four Ni^II formate complexes of the type [Ni(N^∩N)_n][O₂CH]₂ (2, adduct with 3/4 EtOH, N^∩N = en, [e with combining low line] thyle [n with combining low line] ediamine, n = 3; 4, N^∩N = dien, N,N′,N′′- [d with combining low line] [i with combining low line] thyleetriamine, n = 2), [Ni₂(O₂CH)₄(H₂O)(tmeda)₂] (3, tmeda = N,N,N′,N′- [t with combining low line] etra [m with combining low line] ethyl [e with combining low line] thylenei [a with combining low line] mine) and [{Ni(O₂CH)₂(pmdta)}₂·H₂O] (5, pmdta = N,N′,N′,N′′,N′′- [p with combining low line] entaethyl [d with combining low line] iethylenerimine) by a reaction of [{Ni(O₂CH)₂}·2H₂O] (1) with the respective N-donor bases is reported. The structures of 2–5 in the solid state were determined by single X-ray structure analysis, revealing a discrete dinuclear structure of 3 and the formation of polymeric networks in the case of 2, 4 and 5 due to intermolecular hydrogen bonding. SQUID and ESR measurements of 3 evidenced a weak antiferromagnetic coupling between the Ni^II ions and an easy plane magnetic anisotropy. Accompanying quantum chemical studies of the magnetic properties and IR characteristics of 3 were performed to strengthen the conclusions drawn from experimentally obtained data. The thermal decomposition temperatures of 2–5 were determined by TG (thermogravimetry) and obtained residues were analyzed by PXRD (powder X-ray diffraction) measurements. The decomposition processes were completed at 207 (3), 215 (5), 250 (2) and 273 °C (4) and are shown to result in the formation of pure metallic nickel.