On the Microporous Nature of Transition Metal Nitroprussides
2003
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) (Mn2+, Fe2+, Cu2+, Zn2+, and Cd2+), cubic (Fm3m) (Co2+ and Ni2+), and
orthorhombic (Amm2) (Cu2+). 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 H2O, CO2, and
N2. Pores of both orthorhombic and cubic structures are accessible to H2O and CO2 in experiments carried
out at 23 and 0 °C, respectively; however, they are inaccessible to N2 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.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
23
References
43
Citations
NaN
KQI