Hydrothermal synthesis and characterization of hexavanadium polyoxo alkoxide anion clusters: crystal structures of the vanadium(IV) species Ba[V6O7(OH)3{(OCH2)3CCH3}3].3H2O and Na2[V6O7{(OCH2)3CCH2CH3}4], of the mixed-valence complex (Me3NH)[VIV5VVO7(OH)3{(OCH2)3CCH3}3], and of the fluoro derivative Na[V6O6F(OH)3{(OCH2)3CCH3}3].3H2O

Abstract

The hydrothermal reactions of vanadium oxide precursors with trialkoxy ligands of the class (HOCH2)3CR (R = CH3, CH2CH3) yield polyalkoxyoxovanadium clusters with a hexametalate core, Ba[V607(0H)3{(0CH2)3-CCH3}3]-3H20 (1), Na2[V607{(0CH2)3CCH2CH3}4] (2), (Me3NH)[V607(0H)3{(0CH2)3CCH3}3] (3), and Na-[V606F(0H)3{(0CH2)3CCH3}3]'3H20 (4). Cluster 1 is a fully-reduced V(I V) species in which nine doubly bridging oxo groups of the parent {V60i9} core have been substituted by alkoxy oxygen donors of the three trialkoxy ligands. The structure of 3 is grossly similar to that of 1, with differences in metrical parameters reflecting the presence of one oxidized V(V) site in the metal core of 3. The fully reduced cluster 2 exhibits complete substitution of the doubly-bridging oxo groups of the parent core by 12 ligand alkoxy donors. The tendency of polyvanadium oxide clusters to encapsulate a variety of guest molecules or ions is demonstrated by the structure of 4, in which the central Ht-oxo group of the parent core has been substituted by a u3-fiuoride, resulting in a considerably distorted {V6C>6-(m3-F)(m2-OH)3(m2-OR)9J core. Crystal data for 1: hexagonal space group P6}mc, a = 13.707(1) A, c = 9.647(2) A, V = 1569.7(2) A* 123, Z = 2, D^ic -2.140 g cm-3; structure solution and refinement based on 399 reflections converged at R = 0.0576. Crystal data for 2: cubic space group Fd3, a = 19.202

A journey into the electrochemistry of vanadium compounds

“…The hydrothermal reactions of vanadium oxide precursors with trialkoxy ligands of the class (HOCH 2 ) 3 CR (with R = Me, Et) yielded polyalkoxyoxovanadium clusters with a hexametalate core [262]. Only some of them were soluble enough to be electrochemically investigated and data are collected in Scheme 22.…”

A novel cationic heteropolyoxovanadium(iv) cluster functionalized with organic ligands: synthesis and characterization of the fully reduced species [MnIIVIV6O6{(OCH2CH2)2N(CH2CH2OH)}6]Cl2

“…The latter contains an oxidized anionic hexavanadate core adopting the Anderson structure. 4 The other reported examples of the hexavanadate clusters, [12][13][14] which are functionalized with tris(hydroxymethyl)alkane ligands, contain reduced {V 6 O 19 } cores which adopt the Linquist structure. 15…”

An All‐Vanadium(III) Hexametalate Lindqvist Structure and Its Chromium and Iron Analogues

“…[5,6] Here we report the isolation of the six-electron further reduced (i.e., the all-vanadiumA C H T U N G T R E N N U N G (III)) hexavanadate by formally replacing {V ) are very rare and 2) the cluster anions approximate very closely to T d symmetry and this is a rare example in which an analytical solution exists to the spin Hamiltonian for a large cluster. [8] Solvothermal reaction of [VCl 3 A C H T U N G T R E N N U N G (thf) 3 ] with pyridine (1:2) in MeCN at 100 8C, followed by addition of the triol MeC-A C H T U N G T R E N N U N G (CH 2 OH) 3 (2 equiv) and further heating at 150 8C produced crystalline [(V III Cl) 6 …”

“…The hexametalate Lindqvist ion {M 6 O 19 } nÀ , [1] comprising a superoctahedron of condensed {MO 6 } fragments, is one of the classic structures in polyoxometalate chemistry and is known for Mo, W, Nb and Ta. [2] Although the naked vanadium clusters are not known, the all-vanadium(V) form has been stabilised by capping with organometallic fragments.…”

“…Replacement of some or all of the twelve m-oxides with malkoxides, thus reducing the charge of the core (a common route to stabilising polyoxovanadates), [4] can stabilise reduced V IV/V forms [5][6][7] and Zubieta and co-workers isolated the fully reduced, all-V IV hexametalate by using tris-alkoxides in [(V IV 6 O) 6 …”