Syntheses, crystal structures and properties of tetrakis(3-methylpyridine-κN)bis(isothiocyanato-κN)manganese(II) and tetrakis(3-methylpyridine-κN)bis(isothiocyanato-κN)iron(II)

Abstract

The reaction of Mn(NCS)2 or Fe(NCS)2 with 3-methylpyridine (C6H7N) leads to the formation of two isostructural compounds with compositions [Mn(NCS)2(C6H7N)4] (1) and [Fe(NCS)2(C6H7N)4] (2). IR spectroscopic investigations indicate that only terminally coordinated thiocyanate anions are present. This is confirmed by single-crystal structure analysis, which shows that their crystal structures consist of discrete centrosymmetric complexes, in which the metal cations are octahedrally coordinated by two N-bonded thiocyanate anions and four 3-methylpyridine ligands. X-ray powder diffraction (XRPD) proves that pure samples have been obtained. Thermogravimetric measurements show that decomposition starts at about 90°C and that the two coligands are removed in one step for 1 whereas for 2 no clearly resolved steps are visible. XRPD measurements of the residue obtained after the first mass loss of 1 show that a new and unknown crystalline compound has been formed.