*2.5.1. Tetracyano-niquelates synthesis (lamellar materials)*

Depending on the properties desired in the product, many routes of preparation are known. Given its porous nature, it has a certain zeolitic character, which allows you to store small

They have now developed materials under the same principle of formation of Prussian blue by changing the formation of anionic block metals. The hexacyano-cobaltates (of the family of the hexacyano-metallates) are an example of these materials considered as Prussian blue

The hexacyano-metallates of the transition metals are microporous molecular family, whose structures are based on a three-dimensional arrangement of chains M-C≡N-M. Metal M (inner metal), linked to the carbon atom, is always forming octahedral molecular blocks [Mn + (CN) 6] 6-n as the metal M (external metal) acts as an assembler of the octahedral blocks and possibly

The first studies of H2 adsorption in this polymer-coordinated family were published in 2005, simultaneous with the reports of Long et al. [30] and Kepert et al. [31], who studied the formula of general Prussian blue analogues M3 [Co (CN)6]2, known as hexacyano-cobaltates as the internal metal cobalt and being able to change the external metal; M= Mn, Fe, Co, Ni, Cu, Zn,

Figure 5 shows the structure of a Prussian blue analogue in the cubic phase due to the

**Figure 5.** Porous framework for the cubic form, by a hexacyano-cobaltates and a transition metal [30].

Interest in synthesizing nanostructured materials has led to the study of families with specific characteristics. Here two families are addressed: (1) the family of tetracyano-niquelates (II) [with three different external metals, that is, (Co+2) cobalt, nickel (Ni+2), and manganese (Mn

molecules in their cavities [27].

*2.4.1. Hexacyano-metallates*

**2.5. Materials synthesis**

octahedral or tetrahedral coordination [28, 29].

octahedral coordination adopted by the external metal.

analogues.

52 Advances in Petrochemicals

and Cd.

Figure 6 shows the procedure for the synthesis of materials [M (H2O) 2 (Ni (CN) 4) (H2O) *n*: M = Ni, Co, Mn, *n* = 1, 2, 4], which are obtained by the method of precipitation.

**Figure 6.** Materials synthesis M(H2O)2 (Ni(CN) 4)n(H2O): M = Ni, Co, Mn; n=1,2,4 .

Once the corresponding blends are obtained, the resulting precipitated solid is separated by centrifugation, and the solid fraction obtained is repeatedly washed with distilled water to remove the excess ions and then left at room temperature air-dried to constant weight.

*2.5.2. Hexacyano-cobaltates synthesis (porous materials)*

Figure 7 shows the hexacyano-cobaltates synthesis process.

**Figure 7.** Hexacyano-cobaltates synthesis.

The amount in excess of the metals involved guarantees the formation of a single phase. The resulting precipitate remains for a week in the mixture. Then it is separated by centrifugation. The solid fraction is repeatedly washed with distilled water to remove the excess ions, and finally the material is air-dried to constant weight.
