“…For Zn, the XRD powder pattern of the air dried sample corresponds to the rhombohedralFigure 1.Thermo-gravimetric curves for the studied nitroprussides. On heating the water, crystallization is lost and the material becomes anhydrous below 100 °C and then remains stable up to above 160 °C. R trihydrate already reported from a single crystal study (Mullica et al , 1989). This result suggests that the rhombohedral modification of this compound has some stability at room temperature.…”
Section: Resultsmentioning
confidence: 85%
“…In the studied nitroprussides, the water crystallization always appears associated to the M metal, as coordinated water molecules or as zeolitic waters stabilized through hydrogen bonding interactions with the coordinated ones. For Mn, Cd, and Zn, the crystals preserved within the mother liquor are trihydrates, monoclinic P 2 1 / n for Mn and Cd (Mullica et al , 1990) and rhombohedral R on a hexagonal lattice for Zn (Mullica et al , 1989). When these trihydrates are aged in a dry atmosphere, a water molecule per formula unit is lost and the resulting dihydrates are found to be orthorhombic Pnma (Reguera et al , 1996; Gómez et al , 2001).…”
“…For Zn, the XRD powder pattern of the air dried sample corresponds to the rhombohedralFigure 1.Thermo-gravimetric curves for the studied nitroprussides. On heating the water, crystallization is lost and the material becomes anhydrous below 100 °C and then remains stable up to above 160 °C. R trihydrate already reported from a single crystal study (Mullica et al , 1989). This result suggests that the rhombohedral modification of this compound has some stability at room temperature.…”
Section: Resultsmentioning
confidence: 85%
“…In the studied nitroprussides, the water crystallization always appears associated to the M metal, as coordinated water molecules or as zeolitic waters stabilized through hydrogen bonding interactions with the coordinated ones. For Mn, Cd, and Zn, the crystals preserved within the mother liquor are trihydrates, monoclinic P 2 1 / n for Mn and Cd (Mullica et al , 1990) and rhombohedral R on a hexagonal lattice for Zn (Mullica et al , 1989). When these trihydrates are aged in a dry atmosphere, a water molecule per formula unit is lost and the resulting dihydrates are found to be orthorhombic Pnma (Reguera et al , 1996; Gómez et al , 2001).…”
“…3,4,19 For Zn 2+ the obtained crystals are hexagonal (R3) trihydrates. 2 When these trihydrates, both monoclinic and hexagonal, are air-dried they lose a water molecule to form orthorhombic (Pnma) dihydrates, 19 which are the stable phases for these four cations. With the exception of the ferrous salt, the same orthorhombic (Pnma) dihydrates are obtained when the samples are prepared using the precipitation method.…”
Section: Resultsmentioning
confidence: 99%
“…1 The crystal structure of nitroprussides has been resolved in the past decade. [2][3][4][5][6][7][8][9]19,20 This allows an evaluation of their behavior as microporous materials correlating structural and adsorption data. In this contribution, the microporous nature of Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , and Cd 2+ nitroprussides is discussed from their crystal structure and H 2 O, N 2 , and CO 2 adsorption isotherms.…”
Nitroprussides of divalent transition metals form a family of microporous molecular materials. Their properties in this sense depend on the transition metal cation involved and also on the preparative method, which determine their crystal structures. The stable phases of this family of materials belong to one of the following crystal structures: orthorhombic (Pnma) (Mn 2+ , Fe 2+ , Cu 2+ , Zn 2+ , and Cd 2+ ), cubic (Fm3m) (Co 2+ and Ni 2+ ), and orthorhombic (Amm2) (Cu 2+ ). These materials are stable up to above 160°C, while their dehydration takes place around 100°C. On dehydration, Amm2 copper complex changes into a tetragonal (I4mm) phase. The microporous nature of these materials is discussed according to their crystal structure and correlating structural and adsorption data. The accessibility to the pore system was evaluated through adsorption of H 2 O, CO 2 , and N 2 . Pores of both orthorhombic and cubic structures are accessible to H 2 O and CO 2 in experiments carried out at 23 and 0°C, respectively; however, they are inaccessible to N 2 at -196°C. This behavior is discussed as related to the large polarizing power of the nitrosyl (NO) ligand which distorts the local environment of the iron atom and reduces the effective window cross section. The small pores of tetragonal copper nitroprusside were inaccessible to the adsorbates used.
“…Alkali metal nitroprussides crystallize in noncubic space groups (monoclinic and orthorhombic crystal systems) (Bottomley and White, 1979;Amalvy et al, 1986;Soria et al, 1996). Divalent transition metal nitroprussides have also been well characterized from the structural point of view (Gentil et al, 1976;Mullica et al, 1989;Mullica et al, 1990;Reguera et al, 1996). Silver nitroprusside, which is usually used as an intermediate during the preparation of other members of this family of compounds, has not been previously studied.…”
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