# What compound is formed in this case?

I read from a source that the aqueous solution of ferrous sulfate ($\ce{FeSO4}$) gives an unstable brown compound on treating with $\ce{NaNO2}$ and dilute $\ce{HCl}$. Well, it is quite understandable that it is the $\ce{HNO2}$ formed in situ that further causes the reaction. But what is the reaction and what is that unstable compound formed?

$$\ce{NO2^{-} + Fe^{2+} + 2H+ -> NO + Fe^{3+} + H2O}$$
$$\ce{[Fe(H2O)6]^{2+} + NO -> [Fe(H2O)5NO]^{2+} + H2O}$$