Syntheses, characterisation and crystal structures of metal complexes of a novel 1,2-dithiolate ligand, 6,7-dihydro-6-methylene-5H-1,4-dithiepine-2,3-dithiol

Abstract

A series of [NR₄][M(dpdt)₂](R = Bu, M = Ni 2, Au 3 or Cu 4; R = Me, M = Ni 5; H₂dpdt = 6,7-dihydro-6-methylene-5H-1,4-dithiepine-2,3-dithiol) complexes have been synthesized. Magnetic susceptibility measurements indicate that the gold 3 and copper 4 complexes are diamagnetic, whilst the nickel salt 2 is paramagnetic over the temperature range studied (290–22 K). The solution redox properties are consistent with a 1,2-dithiolene structure for these compounds. Single crystal X-ray analysis on compounds 2–4 revealed crystal-packing structures consisting of two crystallographically independent [M(dpdt)₂]^– moieties possessing square-planar geometry, in which there are no intermolecular S ⋯ S contacts shorter than the sum of the van der Waals radii (3.70 Å).