Why does [Co(NO2)6]4- ion have 3 unpaired electron as opposed to 1? Why does $\ce{[Co(NO2)6]^4-}$ ion have 3 unpaired electron as opposed to 1?

The book says that it has 3 unpaired electrons. I thought $\ce{NO2-}$ was a strong field ligand, making $\ce{Co^2+}$ a $\ce{d^7}$ low spin ion. Six electrons go in the $\mathrm{t_{2g}}$ orbital and 1 in the $\mathrm{e_g}$ orbital.

Please explain the bonding in this compound (preferably with a suitable MO diagram to go with it).
According to Elliot, Hathaway &amp; Slade (1966) cited by this paper, Co(II) with nitrite ligands is low spin.



So maybe it is just a typo. For d7 low spin, you would expect one unpaired electron.