Synthesis, spectroscopy, and electrochemistry of heterocyclic thionato complexes of divalent nickel: crystal structure of tetraethylammonium fac-[tris(benzothiazoline-2-thionato)nickelate(II)]
Abstract
The deprotonated anions derived from benzothiazoline-2-thione (C7H5NS2), thiouracil (C4H4N2OS) and 6-amino-2,3-dihydro-2-thioxo-(1H)-pyrimidin-4-one (C4H5N3OS) react with [NEt4]2[NiCl4] in acetonitrile to give [NEt4][Ni(C7H4NS2)3], (1), [NEt4][Ni(C4H3N2OS)3], (2), and [NEt4][Ni(C4H4N3OS)3], (3). Crystal structure analysis shows that (1) crystallises in the monoclinic space group P21/n with a= 10.290(1), b= 19.137(2), c= 16.814(2)Å, β= 101.95(1)°, Z= 4, R= 0.082 from 5 336 unique reflections with F > 4σ(F). The [Ni(C7H4NS2)3]– anion adopts the confacial isomeric form with the metal in a distorted-octahedral environment formed from three, four-membered, S,N-chelating ligands. Average NiII–N and NiII–Sthionate distances are 2.070 and 2.555 Å, respectively, and the mean N–NiII–S angle is 67.8°. Solid-state electronic spectra and room-temperature magnetic moments show that NiII is octahedrally co-ordinated in complexes (1)–(3). They also suggest that the anions have the same isomeric form. Electrochemical measurements show the complexes to be irreversibly oxidised in acetonitrile.