Configurational Isomerism in Polyoxovanadates

Abstract

A water-soluble derivative of the polyoxovanadate {V E O } (E=semimetal) archetype enables the study of cluster shell rearrangements driven by supramolecular interactions. A reaction unique to E=Sb, induced exclusively by ligand metathesis in peripheral [Ni(ethylenediamine) ] counterions, results in the formation of the metastable α * configurational isomer of the {V Sb O } cluster type. Contrary to all other polyoxovanadate shell architectures, this isomer comprises an inward-oriented vanadyl group and is ca. 50 and 12 kJ mol higher in energy than the previously isolated α and β isomers, respectively. We discuss this unexpected reaction in light of supramolecular Sb-O⋅⋅⋅V and Sb-O⋅⋅⋅Sb contacts manifested in {V Sb O } dimers detected in the solid state. ESI MS experiments confirm the stability of these dimers also in solution and in the gas phase. DFT calculations indicate that other, as of yet elusive isomers of {V Sb }, might be accessible as well.

A hexaniobate expanded by six [Hg(cyclam)]2+ complexes via Hg–O bonds yields a positively charged polyoxoniobate cluster

“…Polyoxometalates (POMs) of group 5 and group 6 cations are intensively investigated due to their pronounced structural variety, partially unusual properties and potential applications in several scientific and technological areas [1][2][3][4][5][6][7][8][9][10][11]. Polyoxoniobates (PONbs) are a sub-class of POMs featuring mainly the Lindqvist {Nb 6 O 19 } [12][13][14][15] or Keggin clusters {XNb 12 O 40 } (X = Si, Ge) [16][17][18][19] [12,20] as precursors large PONb clusters were prepared, like, e.g.…”

Soluble Hetero‐Polyoxovanadates and Their Solution Chemistry Analyzed by Electrospray Ionization Mass Spectrometry

“…Although the very prominent cleavage of the dimerici on into monomers is clearly favored by the reduction of charge repulsion, the characteristicl oss of neutral water and hydroxyl radicals from the dimer ions yielding still-intact dimeric product ions was also observed (Figure 16 c). [39] These resultse mphasize the value of the soluble Sb-POV precursor 10 and the knowledge about its solution reactivity for the synthesis of complex new Sb-POV compounds. It also demonstrates that an array of small, yet cooperative effects including the changes to the counter-cation-ligand environment and the intramolecular noncovalent interaction between cluster-cage dimers can drive the formation of the high-energy configurational a 1 *-{V 14 Sb 8 O 42 }i somer.T he analysiso ft his fascinating new compound highlights the ability of mass spectrometry to provide detaileds tructurali nsights into hierarchical self-assembly phenomena of Sb-POVs in solution.…”

“…Depending on the arrangement of the vanadium skeleton, differents tructural isomers exist, whereas numerousm ore are imaginable and density functional theory calculations confirm their feasibility. [19,39,40] During the past decades, Sb-POVsw ere only accessible under hydrothermalo rs olvothermal conditions with low-molecular vanadiums ources like V 2 O 5 ,N H 4 VO 3 , NaVO 3 and VOSO 4 or even vanadium halides. Long reaction times,o ften high temperatures and usually high pH values for reductiver eactionc onditions needed to be appliedb ecause no soluble heteroatom-containing precursor with highern uclearity was accessible for post-functionalization.…”

“…The reaction of this compound with cyclen in aqueous solution yields {Ni(cyclen)(en)} 2 [V 14 Sb 8 O 42 (H 2 O)]· % 10 H 2 O( 11)a fter a short reactiont ime. [39] The compound has undergone al igand metathesis and the {V 15 Sb 6 O 42 }! {V 14 Sb 8 O 42 }t ransformation.…”

GDCh Science Forum Chemistry 2019

“…[4] Bensch gehçrt dem internationalen Beirat der Zeitschrift füra norganische und allgemeine Chemie an. Bensch promovierte 1983 unter Anleitung von Eberhard Amberger an der Ludwig-Maximilians-Universität München.…”