{1-[1-(2-Hydroxyphenyl)ethylidene]-2-(pyridin-2-yl-kN)hydrazine-k2N′,O}{1-[1-(2-oxidophenyl)ethylidene]-2-(pyridin-2-yl-kN)hydrazine-k2N′,O}nickelate(II) nitrate hemihydrate - Mamour, Sarr; Mayoro, Diop; Ibrahima, Thiam Elhadj; Mohamed, Gaye; Hamady, Barry Aliou; Ellena, Javier (Acta Crystallographica E, 2018)