Abstract:We report an ew approach for the synthesis of heterohexa-and heterodecametalates via the use of nonaqueous,m icrowave-assisted reaction conditions.T he two novel molybdovanadates have been isolated and characterized in the solid and solution states using single-crystal X-ray diffraction, FT-IR, UV/Vis,m ultinuclear NMR spectroscopy, and ESI-MS.T he relative stabilities of the possible structural isomers were probed using dispersion-corrected DFT calculations for both polyoxometalate systems.Polyoxometalates (POMs) are molecular early-transitionmetal oxides that can be isolated through the condensation of simple oxyanions to yield oligomeric structures with somewhat predictable structural features and nuclearities.[1] Control of the synthetic conditions within well understood pH and concentration domains can be exploited to yield molecules suitable for further derivatization by incorporation of heteroatoms,o rganometallic complexes,o rg rafting of organic ligands to the surface of the molecular metal oxide.[2] Given this compositional and structural versatility,POMs have been utilized for catalytic, biological, and molecular electronic applications. [3][4][5][6][7][8][9][10][11] Historically the compositional diversification of POMs has been achieved via:reaction of stoichiometric mixtures of the desired constituents in pH controlled media;the addition of electrophiles to preformed plenary or lacunary POMs;o r the covalent functionalization of the POM surface by organic moieties. [12][13][14][15][16][17][18][19][20][21][22][23][24] Often the precise atomic ratios of early transition metals in the products can be controlled, however, occasionally the solution chemistry is sufficiently complex that separation and structural characterization of all products is not possible.[ 3À species". Furthermore,t he resulting arrangement of heteroatoms in POMs bearing oxo ligands of varying basicity and hence propensities for protonation has been utilized over many years.T his enables the direct functionalization of the molecular metal oxide surface by av ariety of alkoxo species resulting in inorganic-organic hybrids with ahost of applications. [27,28] Herein, we build upon our recent efforts towards the microwave-assisted synthesis of POMs [29,30] and report the characterization of two elusive molybdovanadates as their tetrabutylammonium salts (TBA )] (2;F igure 1). Each of the compounds has been characterized in the solid state by X-ray diffraction and FT-IR, and with solution measurements including 1 H-, 13 C-, and 51 V-NMR spectroscopy,E SI-MS and UV/Vis.Q uantumchemically optimized structural isomers,o btained with reliable and modern dispersion-corrected density [31] functional theory (DFT) approximations complement experimental observations and provide insight towards the future rationale preparation of POMs under non-aqueous conditions.Compound 1 was prepared by as imple one-pot microwave-assisted reaction whereby the tetrabutylammonium

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Das Zusatzmaterial "Supporting information" ist über einen Link am Ende des Dokuments abrufbar. Abbildung 1. Kugel-Stab-Modelle der Kristallstrukturen der Heterometallate [V7Mo3O28] 3-(1) -links -und [V3Mo3O16(C5H9O3)] 2-(2)rechts. Position A, orange Kugeln = Vanadium; Position B, grüne Kugeln = angereichert mit Molybdän; Position C, violette Kugeln = angereichert mit Vanadium; Sauerstoff, rote Kugeln; Kohlenstoff, schwarze Kugeln; Wasserstoff, weiße Kugeln.