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I am a bit confused about the correct name of $\mathrm{LaMnO}_3$. Is it lanthanium manganate or lanthanum manganite?

I was assuming that since $\mathrm{SrTiO}_3$ is called strontium titanate, $\mathrm{LaMnO}_3$ 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 $\mathrm{La}_x\mathrm{Sr}_{1-x}\mathrm{MnO}_3$ where they also used the term manganite.

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

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Let's go down the ladder. $\ce{KMnO4}$ is permanganate, Mn(VII). $\ce{K2MnO4}$ is manganate, Mn(VI). $\ce{K4MnO4}$ is manganite, Mn(IV). $\ce{LaMnO3}$ 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. $\ce{SrO + TiO2}$ gives $\ce{SrTiO3}$, 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 $\ce{CH5^+}$. Carbonium ions were renamed carbenium ions to general confusion. Then, $\ce{CH6^{2+}}$. 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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  • $\begingroup$ The last paragraph of your answer does not seem to have anything to do with with the admittedly clunky nomenclature of the metal oxyanions. $\endgroup$ – Ben Norris Apr 22 '14 at 15:16
  • $\begingroup$ Also, your statement about optical isomerism is confusing, given that the direction of rotatation of plane-polarized light is generally unrelated to the absolute spatial geometry of the chiral molecule $\endgroup$ – Ben Norris Apr 22 '14 at 15:19
  • $\begingroup$ Do better: mazepath.com/uncleal/norbors.gif mazepath.com/uncleal/norone.png P3(1)21 quartz and P3(2)21 berlinite are both levorotatory despite being opposite geometric hands, J. Appl. Crystallogr. 19, 108 (1986). CIP notation flips within unchanged geometry (L-(S)-alanine, L-(R)-cysteine). Achiral PhCOCH3 impurity changes resolved PhCH(OH)CH3 optical rotation, J. Org Chem. 38(10), 1870 (1973). $\endgroup$ – Uncle Al Apr 24 '14 at 22:17

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