MnOs compounds

Our discussion will comprise separately the mononitrosyl, polynitrosyl, bridging, and cluster nitrosyl complexes, with emphasis on the first group. We present different types of MNO compounds, without attempting to collect all available structures. Examples with either classical coligands (amines, cyanides, water, polypyridines, etc.) or porphyrin compounds have been chosen, in an attempt to illustrate recent developments in the field. Apart from the information contained in the previous Comprehensive Coordination Chemistry (CCC, 1987)17 a comprehensive review on structures... 

Variable oxidation state is also exhibited in the oxides themselves among metals in this region of electronegativity. Thus lead, for example, forms the monoxide PbO (+2) and the dioxide PbO 2 ( + 4) (the compound Pbj04 is not a simple oxide but is sometimes called a compound oxide). Similarly, manganese gives the oxides MnO and Mn02-... 

An additional problem is encountered when the isolated solid is non-stoichiometric. For example, precipitating Mn + as Mn(OH)2, followed by heating to produce the oxide, frequently produces a solid with a stoichiometry of MnO ) where x varies between 1 and 2. In this case the nonstoichiometric product results from the formation of a mixture of several oxides that differ in the oxidation state of manganese. Other nonstoichiometric compounds form as a result of lattice defects in the crystal structure. ... 

Anionic extractants are commonly based on high molecular weight amines. Metal anions such as MnO or ReO can be exchanged selectively with inorganic anions such as Cl or The equiHbrium for a quaternary onium compound of organic radicals R for two anion species A and B ... 

Divalent manganese compounds are stable in acidic solutions but are readily oxidized under alkaline conditions. Most soluble forms of manganese that occur in nature are of the divalent state. Manganese(Il) compounds are characteristically pink to colorless, with the exception of MnO and MnS which are green, and Mn(OH)2, which is white. The physical properties of selected manganese(Il) compounds are given in Table 6. 

The Mn ion is so unstable that it scarcely exists in aqueous solution. In acidic aqueous solution, manganic compounds readily disproportionate to form Mn ions and hydrated manganese(IV) oxide, Mn02 2H20 in basic solution these compounds hydroly2e to hydrous manganese(III) oxide, MnO(OH). Sulfuric acid concentrations of about 400 450 g/L are required to stabilize the noncomplexed Mn ion in aqueous solutions. 

The most important manganese(V) compound is K MnO, a key intermediate in the manufacture of potassium permanganate. Potassium manganate(V) is an easily crystallized salt obtained by reduction of potassium permanganate using sodium sulfite in strong sodium hydroxide solution. This was the first compound to be recognized as exclusively pentavalent. 

Manganese(VII) compounds containing the cationic permanganyl ion, MnO" 2> known. For example, permanganyl fluoride [15586-97-7],... 

The purple permanganate ion [14333-13-2], MnOu can be obtained from lower valent manganese compounds by a wide variety of reactions, eg, from manganese metal by anodic oxidation from Mn(II) solution by oxidants such as o2one, periodate, bismuthate, and persulfate (using Ag" as catalyst), lead peroxide in acid, or chlorine in base or from MnO by disproportionation, or chemical or electrochemical oxidation. 

The most significant nonferrous use of manganese compounds is for primary batteries, where manganese dioxide is the principal constituent of the cathode mix. In the standard Leclanchn ceU, 2inc and ammonium chloride are mixed to form the electrolyte, a mixture of carbon and MnO forms the cathode, and 2inc acts as the anode (221). The principal ceU reaction is as foUows ... 

Thallium (1) salts are oxidized only by very powerful oxidizing agents, eg, MnO or Cl, iu acid solutions. The properties of the more important thallium compounds are Hsted in Table 2. 

Determination as the tetraphenylarsonium compound Discussion. Any ions forming a precipitate with tetraphenylarsonium chloride (e.g. MnO, ClOj, Br , I-, I03 and SCN-) will interfere. Difluorophosphates give slight interference which can be overcome by boiling the solution for a few minutes to hydrolyse difluorophosphate the hexafluorophosphate ion is not affected by this treatment. 

The slow step of this reaction corresponds to removal of hydride from an anion and finds several counterparts in oxidations of organic compounds by MnO. The anion may have the structure... 

In the first series, there are a large number of compounds of elements with a low oxidation state (II or III like MnO ) whereas there are only a few compounds with oxidation states II or III in the higher series. Compounds with oxidation states IV and VIII are the most stable. This phenomenon can be obsen/ed in all the groups of the periodic table. 

A ternary compound does not yield three elements this one yields an element and a simpler compound. The MnO, may be indicated over or below the arrow, or it may be omitted entirely. 

The differences in spin transfer observed in MnO and MnC03 are consistent with the respective values of Rv for the two compounds. 

LaMn03 is an intrinsic p-type conductor. Electronic conductivity is enhanced by substitution of the La3+ site with divalent ions such as strontium or calcium. Of the alkaline-earth dopants, Sr substitution is preferred for SOLC applications because the resultant perovskite forms stable compounds with high conductivity in the oxidizing atmosphere found at the cathode [41], Extensive data show that La, xSi. MnO where x = 0.1 - 0.2, provides high conductivity while maintaining mechanical and chemical stability with YSZ [41, 42],... 

---