Heteronuclear complexes. Metal ion induced paramagnetism in a metal-containing diamagnetic chelating agent

Abstract

The diamagnetic bidentate chelating agent bis(2-mercaptoethylamine)nickel(II) forms heterometallic complexes upon reacting with various metal ions. The cadmium complexes having the general formula [[(Ni(NH 2CH 2CH 2S) 2] 2Cd]CdX 4, are diamagnetic however the analogous mercury complexes [[Ni(NH 2CH 2CH 2S) 2] 2Hg][HgX 4], where X = Cl, Br are paramagnetic. The exception is [[Ni(NH 2CH 2CH 2S) 2] 2Hg][HgI 4] which is diamagnetic. The electronic spectrum of this complex is consistent with a square planar environment around the nickel(II) ions. However, [Ni(NH 2CH 2CH 2S) 2HgX 2] n complexes where X is Cl or Br have the electronic spectra which are consistent with a six coordinate environment around the nickel(II) ions. The infrared spectra of the chloride complex indicated that this compound did not contain the HgCl 4 −2 anion. The X-ray powder patterns of all three complexes are different as are the infrared spectral patterns. The magnetic susceptibilities were measured form room temperature to 5 K and these complexes are ferromagnetic in character. However, the magnetic data could not be fit to any model. Comparisons are made with similar polymetallic complexes such as [Ni(NH 2CH 2CH 2S) 2] 2HgY 2 where Y = NO 3 −, Cl −, and SCN −. Based on the above the data it is believed that [Ni(NH 2CH 2CH 2S) 2HgX 2] n complexes where X is Cl or Br are polymeric. However, the [Hg[Ni(NH 2CH 2CH 2S) 2] 2]X 2 where X = HgI 4 −2, NO 3 −1 and Cl −1 can be best represented as a ionic complex containing a trimetallic cation.