Manganese complexes magnetic susceptibility

The magnetic susceptibilities of [Mn(bipy)3],2THF and Li[Mn(bipy)3],4THF have been determined over the range 1.5 to 300 K. The susceptibility of the latter can be best explained on a radical-ion model in which three bipyridyl radical-ion ligands are co-ordinated to manganese(n) i.e. [Mn2+(bipy )3] rather than [Mn (bipy)3]. A similar model is also proposed for the other complex.68 The octahedral polymers Mn(4,4 -bipy)X2 (X = Cl or Br) have been prepared.69... 

The present paper summarizes the oxidation-reduction chemistry of the gluconate complexes of Mn(II), Mn(III), and Mn(IV) in alkaline media. Electrochemical, spectrophotometric, and magnetic susceptibility measurements have been used to establish the formulas and chemical characteristics of the complexes. The oxidation-reduction chemistry for the manganese complexes formed by other ligands with polyhydroxyl functions also has been determined. 

While the stoichiometries of the Mn SOD enzymes appear to vary, the properties of the Mn-binding site do not. This is borne out in the electronic spectra of these proteins, which display a great degree of similarity despite the diversity of sources from which they have been isolated (Table II). This type of spectrum is distinctive for manganese in the trivalent oxidation state (3). The native enzymes are EPR silent, as might be anticipated if they contained Mn solely as the trivalent ion (S = 2) (1, 6,12,18-20, 24). However, when the enzymes are denatured, the characteristic six-line pattern of Mn(II) (I = 5/2) appears. Magnetic susceptibility studies with the E. coli SOD were consistent with the presence of a monomeric Mn(III) complex with a zero-field splitting of 1 to 2 cm-1 (4). The enzymes are additionally metal specific (however, see Refs. 36 and 37) metal reconstitution studies with E. coli and B. stearothermophilus revealed a strict requirement for Mn for superoxide dismutase activity (2, 22, 23). 

---