Nickel(IV) dithiocarbamato complexes of the [Ni(ndtc)3]X type: X-ray structure of [Ni(hmidtc)3][FeCl4]

A series of fourteen octahedral nickel(IV) dithiocarbamato complexes of the general formula [Ni(ndtc)3]X·yH2O {ndtc stands for the appropriate dithiocarbamate anion, X stands for ClO4− (1–8; y = 0) or [FeCl4]− (9–14; y = 0 for 9–12, 1 for 13 and 0.5 for 14} was prepared by the oxidation of the corresponding nickel(II) complexes, i.e. [Ni(ndtc)2], with NOClO4 or FeCl3. The complexes, involving a high-valent NiIVS6 core, were characterized by elemental analysis (C, H, N, Cl and Ni), UV–Vis and FTIR spectroscopy, thermal analysis and magnetochemical and conductivity measurements. The X-ray structure of [Ni(hmidtc)3][FeCl4] (9) was determined {it consists of covalently discrete complex [Ni(hmidtc)3]+ cations and [FeCl4]− anions} and this revealed slightly distorted octahedral and tetrahedral geometries within the complex cations, and anions, respectively. The Ni(IV) atom is six-coordinated by three bidentate S-donor hexamethyleneiminedithiocarbamate anions (hmidtc), with Ni–S bond lengths ranging from 2.2597(5) to 2.2652(5) Å, while the shortest Ni···Cl and Ni···Fe distances equal 4.1043(12), and 6.2862(6) Å, respectively. Moreover, the formal oxidation state of iron in [FeCl4]− as well as the coordination geometry in its vicinity was also proved by 57Fe Mössbauer spectroscopy in the case of 9.

The distorted octahedral nickel(IV) complexes [Ni(ndtc)3]X·yH2O (X = ClO4− for 1–8; X = FeCl4− for 9–14; y = 0–1) were synthesized and characterized. The complex cations consist of three dithiocarbamate anions (ndtc) bidentate-coordinated to the central Ni(IV) atoms through both of their sulfur atoms, thus forming a high-valent NiIVS6 core, as demonstrated by a combination of a magnetic study of all the complexes and an X-ray crystallographic study of the complex [Ni(hmidtc)3][FeCl4−].Figure optionsDownload as PowerPoint slideHighlights
► Synthesis and characterization of fourteen nickel(IV)-dithiocarbamato complexes.
► X-ray structure of [Ni(hmidtc)3][FeCl4] was determined.
► Three bidentate S-donor ligands coordinate to the central Ni(IV) atom.