Chromium(II) chemistry. Part 13. Thiocyanates

Abstract

Chromium(II) forms the pentathiocyanatochromate(II), Na₃[Cr(CNS)₅]·9H₂O, which from magnetic, diffusereflectance, and i.r. data contains a square-pyramidal arrangement of N-bonded thiocyanates. Attempts to prepare similar salts of other metal cations have been unsuccessful, and organic cations give a series of tetrathiocyanatochromates(II), [A]₂[Cr(CNS)₄][A = NMe₄, NEt₄, NPrⁿ₄, NBuⁿ₄, Hhex, Hpy, 1/2H₂en, or 1/2H₂L; hex = hexamine (hexamethylenetetramine), py = pyridine, en = ethylenediamine, and L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene]. In general these complexes show antiferromagnetic behaviour, and are belived to have thiocyanato-bridged structures. Monoethanol adducts of the [NEt₄]⁺ and [NPrⁿ₄]⁺ salts have also been isolated, and found to be magnetically normal. The [NBuⁿ₄]⁺ salt is isolated in two forms, one brown and magnetically normal, and the other blue and antiferromagnetic.