What is the formula of manganese oxohydroxide: MnOOH and MnO(OH)2?

I found various formulae of manganese oxohydroxide. Some site says it is $\ce{MnOOH}$, other say it is, $\ce{MnO(OH)2}$. So, which one is correct?


1. The mineral [manganite](https://en.wikipedia.org/wiki/Manganite) is considered manganese oxide-hydroxide $\ce{MnOOH}$, but [yahoo answer](https://in.answers.yahoo.com/question/index?qid=20080523223626AAnv6dS) claims that it is $\ce{MnO(OH)2}$.
2. In [Winkler titration](https://en.wikipedia.org/wiki/Winkler_test_for_dissolved_oxygen), $\ce{MnO(OH)2}$ is formed:


$$\ce{2 MnSO4(s) + O2(aq) → 2 MnO(OH)2(s)}$$


There is some uncertainty about whether the oxidised manganese is tetravalent or trivalent. Some sources claim that $\ce{Mn(OH)3}$ is the brown precipitate, but hydrated $\ce{MnO2}$ may also give the brown colour. So, is $\ce{MnO(OH)2}$ hydrated $\ce{MnO2}$?


So which one is manganese oxohydroxide- $\ce{MnOOH}$ or $\ce{MnO(OH)2}$? 




First, the difference the substances is the oxidation number of manganese. In $\ce{MnOOH}$, the oxidation number of manganese is 3+. While in $\ce{MnO(OH)\_2}$, the oxidation number for manganese is 4+.


However this doesn't mean $\ce{MnOOH}$ is manganese (III) oxyhydroxide and $\ce{MnO(OH)\_2}$ is manganese (IV) oxyhydroxide, not for $\ce{MnO(OH)\_2}$ at least. If you move the element around, you will get $\ce{MnO(OH)\_2}$ is actually $\ce{H\_2MnO\_3}$. $\ce{H\_2MnO\_3}$ is dihydroxy(oxo)manganese which is an acidic substance.


For the question regarding the structure for both substances, I'm sorry that I don't haven't the image but I can describe it (Hope that would do). For $\ce{MnOOH}$, manganese is single bonded with $\ce{OH}$ and manganese is double bonded with oxygen. For $\ce{MnO(OH)\_2}$, manganese have two single bonds with both of the $\ce{OH}$ and manganese is double bonded with oxygen.


In conclusion, $\ce{MnOOH}$ is manganese (III) oxyhydroxide and $\ce{MnO(OH)\_2}$ is dihydroxy(oxo)manganese. In structure wise, manganese is single bonded with $\ce{OH}$ and manganese is double bonded with oxygen for $\ce{MnOOH}$. For $\ce{MnO(OH)\_2}$, it likes $\ce{MnOOH}$ but have one more single bond with $\ce{OH}$.


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