Mn cations

Deposition of MnO from a solution containing Mn cations on the anode is not considered the primary electrode process. Initially the Mn (ITT) ion is formed on the anode (73). MnO formation arises from Mn(TTT) disproportionation ... 

The most obvious features of Fig. 24.1 are the relative positions of the -t-2 oxidation states. For manganese this state, represented by the high-spin Mn cation, is much the most stable. This may be taken as an indication of the stability of the symmetrical d electron configuration. 

The lower oxides of manganese are basic and react with aqueous acids to give salts of Mn and Mn cations. The higher oxides, on the other hand, are acidic and react with alkalis to yield oxoanion salts, but the polymerization which was such a feature of the chemistry of the preceding group is absent here. 

Prior to the evaluation of Li[Mn2]04 as a rechargeable cathode material, the ideal spinel framework [Mn2]04, (commonly referred to as A — Mn02, after Hunter) was chemically synthesized by acid digestion of Li[Mn2]04 [121]. The formation of A— Mn02 by chemical methods differs from the electrochemical reaction because it dissolves 25 percent of the Mn cations from the original spinel framework ... 

As a defined ternary B-C-N compound is not known, other starting materials are to be considered in order to synthesize one of the, yet unknown, La-B-C-N compounds. Solution chemistry routes were successfully performed with tetra-cyanoborates to synthesize the compounds A[B(CN)4] with monovalent A = Li, Ag, Cu cations, and M[B(CN)4]2 with divalent M = Hg, Cu, Zn, Mn cations [47]. 

Figure 9.7 Electron configurations possible for Mn cations in an octahedral crystal field low spin (LS), intermediate spin (IS), and high spin (HS).

The synthesis of the Y zeolite-encapsulated manganese complex of the salen ligand has been reported recently [51]. It was found to have catalytic activity in the oxidation of cyclohexene, styrene, and stilbene with PhlO. Typically, 1 Mn(salen) is present per 15 supercages, resulting in catalytic turn-overs in the order of 60. The reactions investigated with the respective product yields are given in Scheme 5. Typical oxidation products are epoxides, alcohols and aldehydes. In comparison to the homogeneous case encapsulation seems to lower the reaction rate. From cyclohexene the expected oxidation product cyclohexene oxide is present in excess and is formed on the Mn(salen) site. 2-cyclohexene-l-ol is probably formed on residual Mn cations via a radical mechanism. 

Table 2. Losses of H20 and HDO from metastable complexes of 2-butanols with Mn+ cations in the gas phase [21]a,b...

Figure 4.20 The moving concentration waves corresponding to variations in the oxidation state of the IVln + Mn + cations during the BZ reaction in a cylindrical reactor. The pattern presents the time evolution of the concentration profiles along the reactor, which is observed using the NMR tomographic technique. The dark regions indicate a higher concentration of Mn +. A total of Mn concentration is 0.006 M [7].

There is also some interplay between the and Mn cations. The RNA polymerase isolated from Euglena gracilis grown on a zinc-deficient medium contains two Zn per molecule but differs from the RNA polymerases isolated from zinc-sufficient cells. The messenger RNA from the zinc-deficient cells had a different base composition, with a two-fold increase in the (G+ C)/(A-I-U) ratio. Since intracellular [Mn ] increases in zinc-deficient cells, the effect of [Mn " ] on the RNA polymerase from zinc-deficient cells was investigated. It was shown that increased levels of Mn " lead to increased incorporation of GMP relative to UMP. ... 

Another typical case which deserves to be mentioned is the complexion of a ligand L with a metal cation Mn+. Cations have all tightly-bound water molecules belonging to the first solvation shell. Microscopic models composed by bare L and Mn+ are not sufficient at least the first solvation... 

Redfern, S.A.T., Dove, M.T., Wood, D.R.R. (1997b) Static lattice simulation of feldspar solid solutions ferroelastic instabilities and order/disorder. Phase Trans 61 173-194 Redfern, S.A.T., Knight, K.S., Henderson, C.M.B., Wood, B.J. (1998) Fe-Mn cation ordering in fayalite-tephroite (FexMni U2Si04 olivines a neutron diffraction study. Mineral Mag 62 607-615 Redfern, S.A.T., Harrison, R.J., O Neill, H.St.C., Wood, D.R.R. (1999) Thermodynamics and kinetics of cation ordering in MgAl204 spinel up to 1600°C from in situ neutron diffraction. Am Mineral 84 299-310... 

All of these species involve oxyanions except the Mn cation, which is stabilised as a hexaaquo cation, [Mn"(OH2)6] . In these two halfreactions the number of electrons involved in the oxidation process... 

Comparing the distribution of Mn zones in 10% seawater and 10% seawater-humic acid (HAM sample) it is evident that there is a decrease of the amount in the Mn cationic zone, the cationic tailing increases (up to 20% at the HAM concentration of 200 mg dm ) as well as the immobile zone (up to 20%) and the anionic tailing zone (up to 5%). However, at higher pHs it is possible to get an anionic zone of... 

Electron spin resonance spectroscopy was used to characterize interactions between the Rations in bulk samples and in solution. In the solid state the Mn cations of Mh-SPS are primarily associated. In solution the ratio between associated and isolated ions depends upon the polarity of the solvent. The more polar the solvent, the greater is the extent of isolation of the cations. Preliminary ESR spectra of Cu-SPS are in qualitative agreement with this conclusion. 

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