Formation from ammonium heptamolybdate

AMMONIUM compounds). Diammonium dimolybdate [27546-07-2] (NH 2 2 7 " ble commercially as the tetrahydrate and prepared from MoO and excess NH in aqueous solution at 100°C, has an infinite chain stmcture based on MoO octahedra. In aqueous solution the behavior of Mo(VI) is extremely pH-dependent (4). Above pH 7 molybdenum(VI) occurs as the tetrahedral oxyanion MoO , but below pH 7 a complex series of concentration-, temperature-, and pH-dependent equiUbria exist. The best known of these equiUbria lead to the formation of the heptamolybdate,... 

Bimetallic Co(Ni)-Mo carbides can also be synthesized due to the decomposition of precursors (metal-hexamethylenetetramine complexes) in an inert atmosphere [9, 10], This is a simple one-stage method of the formation of double C03M03C and CogMogC carbides [11], In [12], the Co Moi j oxides prepared from aqueous solutions of cobalt nitrate and ammonium heptamolybdate were carbonized in a flow of pure methane and hydrogen (20% CH4/H2 mixture) to form double carbides. 

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