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Polunin R.A.,Ukrainian Academy of Sciences | Kolotilov S.V.,Ukrainian Academy of Sciences | Kiskin M.A.,RAS Kurnakov Institute of General and Inorganic Chemistry | Cador O.,Equipe Organometalliques et Materiaux Moleculaires | And 8 more authors.
European Journal of Inorganic Chemistry | Year: 2011

The temperature dependence of crystal structure parameters of isostructural coordination polymers Fe2MO(Piv)6(bipy) 1.5·2DMF [1·2DMF and 2·2DMF, where M = Ni II or CoII, respectively, Piv = (CH3) 3CCO2 -, bipy = 4,4-bipyridine and DMF is N,N-dimethylformamide] was studied at five temperatures in the range from 120 to 296 K. The X-ray structure of the N,N-diethylformamide (DEF) solvate of the same coordination polymer 1, Fe2NiO(Piv)6(bipy) 1.5·2DEF (1·2DEF), was studied at 173 and 260 K. Both the DMF and DEF solvates possess similar crystal structures, consisting of a series of parallel 2D polymeric layers with honeycomb voids. These series of parallel layers intersect, leading to their interpenetration and formation of zig-zag channels. It was found that the change of temperature and/or solvent molecule in the pores causes significant structural rearrangement associated with a change of the separation between parallel layers and the angle between intersecting layers. These structural changes lead to a variation of the calculated solvent-accessible volume from 0.21 cm3 g-1 (120 K, 2·2DMF) to 0.30 cm3 g-1 (260 K, 1·2DEF) for a probe molecule with r = 1.4 Å. These changes can model structural transformations which can occur at desolvation and adsorption of guests. Adsorption of n-hexane, n-octane, methanol and ethanol by Fe 2MO(Piv)6(bipy)1.5 was studied. The sorption isotherms of alkanes were typical for microporous sorbents and in this case the behaviour of the coordination polymers resembled that which is typical for sorbents with a rigid structure. In a contrast, alcohol sorption capacity continuously grew at increasing pressure which may be caused by structural transformations, similar to temperature-induced structural transformations. Among the studied sorbates, sorption capacity grew in order methanol < ethanol < n-hexane < n-octane which may be caused by the hydrophobic nature of the channels (due to the presence of tert-butyl groups). Structural parameters of a row of coordination polymers gradually varied depending on the temperature or size of solvent molecules in the voids. This can be considered as a model of changes occurring at desolvation of the polymers or adsorption of guests. Sorption capacity of these compounds is of the order methanol < ethanol < n-hexane < n-octane. This is consistent with hydrophobic channels. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Polunin R.A.,Ukrainian Academy of Sciences | Kolotilov S.V.,Ukrainian Academy of Sciences | Kiskin M.A.,RAS Kurnakov Institute of General and Inorganic Chemistry | Gavrilenko K.S.,Ukrainian Academy of Sciences | And 4 more authors.
Russian Chemical Bulletin | Year: 2010

The reaction of trinuclear acetate complexes Fe2MO(AcO) 6(H2O)3 (M = Ni2+, Co2+) with 4,4′-bipyridine (bpy) results, depending on the reaction conditions, in porous coordination polymers with the composition Fe2MO(AcO) 6(bpy)1.5 (with retention of the metal core Fe 2MO(AcO)6) or nonporous coordination polymers with the composition M2(AcO)4(bpy)2 (with destruction of the metal core Fe2MO(AcO)6). The adsorption and desorption properties of the compounds Fe2MO(AcO)6(bpy) 1.5 with respect to nitrogen and hydrogen were studied. The reaction of hexanuclear benzoate complex Mn6O2(PhCOO) 10(MeCN)4 with bpy or trans-1,2-bis(4-pyridyl)ethylene (bpe) in DMF results in destruction of the metal core Mn6O 2(PhCOO)10 and formation of nonporous coordination polymers, while the pivalate complex Mn6O2(Piv) 10(EtOH)3(HPiv) under the same conditions gives rise to the coordination polymer containing Mn6O2(Piv) 10 structural blocks. © 2010 Springer Science+Business Media, Inc.

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