Mono-and bis-templated cyclic polyoxothiomolybdates with succinate and fumarate ions

摘要

The action of succinate and fumarate ions as template on the self-condensation of the{Mo2O2S2}building block led to the bis-templated ring[Mo12O12S12(OH)12(C4H4O4)2]~(4-)(1)(noted[Mo12-succ2]~(4-))and the mono-templated ring[Mo12O12S12(OH)12(OH2)4(C4H2O4)]~(2-)(2)(noted[Mo12-fum]~(2-)),respectively.Compounds 1 and 2 have been isolated as rubidium salt and structurally characterized by single crystal X-ray diffraction study.Both the compounds have been characterized in solution by ~1H NMR,in D2O.Such a study reveals that a dynamic exchange exists for 1,involving successive transfers of a succinate ion through the open-cavity delimited by the Mo12-ring.Thermodynamic data for such successive exchange are given.Nevertheless,variable temperature ~1H NMR experiments in CD3CN for 1 and 2 show that no conformational change has been detected between 303 and 227 K for the alkyl chain of the central fumarate and succinate ions.A short discussion was begun upon the structural relationships between the size of the alkyl chain and the nuclearity of the inorganic host.