Synthesis and structural characterization of tris(ethylenediamine)nickel(II) dichromate

Abstract

The reaction of tris(ethylenediamine)nickel(II) dichloride dihydrate with potassium dichromate or potassium chromate results in the formation of mixed metallic compounds tris(ethylenediamine)nickel(II) dichromate [Ni(en)(3)][Cr(2)O(7)] (1) (en = ethylenediamine) and tris(ethylenediamine)nickel(II) chromate [Ni(en)(3)][CrO(4)] (2). Both compounds were characterized by analysis, spectra, magnetic susceptibility, and the structure of 1 was determined. [Ni(en)(3)][Cr(2)O(7)] (1) crystallizes in the centrosymmetric monoclinic space group P2(1)/c and its structure consists of a [Ni(en)(3)](2+) dication and a dichromate dianion, with all the atoms situated in a general position. Two carbons of one coordinated (en) in 1 and the hydrogens attached to the amine nitrogen in the same ligand are disordered over two positions. In the crystal structure, tris(ethylenediamine)nickel(II) cations are linked to the [Cr(2)O(7)](2+) anions with several weak hydrogen bonding interactions resulting in an extended network. The chi versus T plots of 1 and 2 reveal simple paramagnetic behavior.