SYNTHESIS, CRYSTAL STRUCTURE AND PROPERTIES OF NOVEL COMPOSITE COMPLEX: [La(NMP)_4(H_2O)_4][HSiMo_(12)O_(40)] centre dot 2NMP centre dot H_2O

摘要

A new composite complex of [La(NMP)_4(H_2O)_4][HSiMo_(12)O_(40)] centre dot 2NMP centre dot H_2O (NMP=N-methyl-2-pyrrolidone) was synthesized and characterized by IR, UV, ESR, TG-DTA and single crystal structural analysis. The water and organic ligands (NMP) coordinate directly with La(III) to form a dodecahedral complex and the SiMo_(12)O_(40)~(4-) anion is the counter ion. IR and X-ray analysis show that there is strong interaction between the polyoxometalate and organic donors. The complex is strongly photosensitive under irradiation with sunlight, resulting in a charge-transfer complex by oxidation of the N-methyl-2-pyrrolidone and reduction of the polyoxometalate. Low temperature ESR spectra indicate thermal electron delocalization among the Mo atoms in the title compound.