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Sequential transformations in assemblies based on octamolybdate clusters and 1,2-bis(4-pyridyl)ethane

Abstract:

The new hybrid inorganic-organic solids [Mo8O 26][H2bpe]2 (1), {[Mo8O 26(μ-bpe)][H2bpe]2}n (2), [Mo8O26(Hbpe)2][H2bpe] (3), and {[Mo8O26][H2bpe]2}n (4) were synthesized under hydrothermal conditions. The crystal structure of 1 contains the discrete octamolybdate β-isomer, whereas in 3 the inorganic building unit is a functionalized octamolybdate of general formula [Mo 8O26X2](2n+4). A similar building unit is found in 2 and 4, but forming part of polymeric 1D-arrays. In 2 the polymer is constructed from [Mo8O26(μ-bpe)] 4-, and the functionalization of the anionic cluster in 4 occurs through Mo-O-Mo bonds. The sequential hydrothermal 2/3 → 1 and 1 → 4 transformations were observed at 145 and 180°C, respectively. However, thermal studies of 1 and 4 revealed that both materials do not suffer any phase transitions below 340°C for 1 or <350°C for 4, indicating that such transformations are possible only under the hydrothermal conditions. An XRPD study as a function of the temperature of 1 also demonstrated the negligible structural changes before 330°C. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.