Metathesis of the perchlorate anions in [Cu5(ahpha) 4](ClO4)2·4H2O, where ahpha2- is the dianion of 3-amino-3-hydroximinopropane hydroxamic acid, with m- and p-phthalates resulted in formation of [Cu5(ahpha) 4(m-C8H4O4)(H2O)] ·9H2O (1), [Cu5(ahpha)4(m-C 8H4O4)(H2O)]·2MeOH· DMF (1a) and [Cu5(ahpha)4(p-C8H 4O4)(H2O)2]2· 14H2O (2). Molecules in the structures of 1, 1a and 2 are held together by noncovalent interactions, and the lattices contain voids filled with water molecules. Compounds 1 and 1a differ in the mode of m-phthalate coordination, solvent type, and crystal lattice content. Desolvated 1 and 2 sorb gaseous MeOH and EtOH. Whereas the MeOH sorption capacity was very similar for 1 and 2 (about 0.14 cm3/g at PPS-1 = 0.9, where P is the current methanol pressure and PS the saturation vapor pressure of methanol at 293 K), the capacity of 2 to sorb EtOH was about 1.5 times as high as that of 1. To a certain extent, the structures of 1 and 1a can be considered as models of compounds that can form at different stages during alcohol sorption by desolvated 1. The ÏMT vs. T data for 1 and 2 could be fitted with a model based on the Hamiltonian H(CuII 5) = -2J1(S1·S2 + S 1·S3 + S1·S4 + S 1·S5) - 2J2(S2·S 5 + S2·S3 + S3·S 4 + S4·S5), where S1 represents the spins of the central CuII ions and S 2-S4 correspond to the spins of the peripheral Cu II ions. The best fits corresponded to J1 = -129(3) cm-1, J2 = -66(1) cm-1 and zJ′ = -2.5(2) cm-1 at gCu = 2.12(1) for 1, and J1 = -163(3) cm-1, J2 = -78(1) cm-1 and zJ′ = -1.5(1) cm-1 at gCu = 2.05(1) for 2. Three complexes were obtained starting from a pentacopper 12-metallacrown-4 and isomeric benzenedicarboxylates. The structures of the complexes determined by XRD may be considered as models of intermediates that form during the interaction of these non-rigid sorbents with alcohols.
All Science Journal Classification (ASJC) codes
- Inorganic Chemistry