Monday, 27 April 2015

inorganic chemistry - About the nomenclature: manganate or manganite?


I am a bit confused about the correct name of LaMnO3. Is it lanthanium manganate or lanthanum manganite?


I was assuming that since SrTiO3 is called strontium titanate, LaMnO3 would then be called lanthanium manganate, but I got confused when I heard a collegue referring to it as manganite and after reading a wikiepdia article on LaxSr1xMnO3 where they also used the term manganite.


Which is the correct form, or are they simply interchangeable?



Answer



Let's go down the ladder. KMnOX4 is permanganate, Mn(VII). KX2MnOX4 is manganate, Mn(VI). KX4MnOX4 is manganite, Mn(IV). LaMnOX3 is called both manganate and manganite, but Mn(III). In a proper world it should be lower than that manganite. They are pedagogically both wrong if it is La(III).



http://dictionary.sensagent.com/potassium%20manganite/en-en/


Manganese oxidation state nomenclature is a real world mess. Drawing nomenclature parallels to Cl(VII) and downward is not valid. Drawing nomenclature parallels to titanium is poor, for Ti(IV) is the highest common oxidation state. SrO+TiOX2 gives SrTiOX3, properly called titanate, for it is Ti(IV) on both sides.


Organic had the same problem. The highest valence carbocation was tricoordinate, hence a carbonium ion. Magic Acid gave CHX5X+. Carbonium ions were renamed carbenium ions to general confusion. Then, CHX6X2+. Organic dropped the ball with direction of optical rotation versus geometric left and right. It was flat out stupid designating E ("trans") and Z ("cis") olefins. The designation should have been abstract rather than language-originated.


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