New Water‐Soluble Cluster Compound {Zn(en)₃}₃[V₁₅Sb₆O₄₂(H₂O)]⋅ (Ethylenediamine)₃⋅10 H₂O as a Synthon for the Generation of Two New Antimonato Polyoxovanadates

Abstract

A new antimonato polyoxovanadate {Zn(en) } [V Sb O (H O)]⋅3 en⋅10 H O (en=ethylenediamine) synthesized under hydrothermal conditions exhibits remarkable solubility in water. Electrospray ionization mass spectrometry (ESI-MS) investigations on an aqueous solution demonstrate that the cluster core remains fully intact for 72 h. At longer times, slow transformation into a {V Sb O } cluster is observed. The conversion reaches 50 % after 14 days and is complete after approximately 20 days. The rate of this {V Sb }→{V Sb } cluster transformation is significantly increased in the presence of ammonium acetate. Applying the new compound as a synthon in the presence of 1,10-phenanthroline (phen) led to crystallization of {Zn(phen) } [Zn(en) V Sb O (H O)]⋅23 H O after a short reaction time, whereas addition of Sb O led to fast crystallization of {(Zn(en) (H O) )(Zn(en) )}[Zn(en) V Sb O (H O)] ⋅8.5 H O. In the crystal structure of {Zn(en) } [V Sb O (H O)]⋅3 en⋅10 H O, the en molecules are seen to be attached to the cluster anion through Sb-N bonds. In the structures of the two new compounds obtained, the [V Sb O (H O)] anions are expanded by Zn -centered complexes through Zn-O-V bond formation.

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

“…The ESI‐MS investigations indicated that the {V 15 Sb 6 O 42 }→{V 14 Sb 8 O 42 } transformation could be accelerated by the addition of ammonium additives . Under stirring conditions, the transformation could reach full conversion after only 4 h at 150 °C, resulting in formation of [{Ni(en) 2 } 2 V 14 Sb 8 O 42 ]⋅5.5H 2 O featuring the β ‐isomer of the {V 14 Sb 8 O 42 } moiety .…”

“…A second water‐soluble Sb‐POV, namely {Zn(en) 3 } 3 [V 15 Sb 6 O 42 (H 2 O)]⋅3 en⋅10 H 2 O 12 (Zn‐{V 15 Sb 6 }) was synthesized by our group using solvothermal synthesis starting from low‐nuclearity materials . It exhibits a significantly increased solubility in water compared to the water‐soluble Ni‐{V 15 Sb 6 } precursor 10 and enabled the synthesis of two new Sb‐POV compounds, {Zn(phen) 3 } 2 [Zn(en) 2 V 15 Sb 6 O 42 (H 2 O)]⋅23 H 2 O 13 and {(Zn(en) 2 (H 2 O) 2 )(Zn(en) 2 )}[Zn(en) 2 V 15 Sb 6 O 42 (H 2 O)]⋅8.5 H 2 O 14 , by very convenient post‐functionalization procedures in a short reaction time of 24 hours at 150 °C.…”

“…Af ormal exchange of aV Oa gainst an SbÀOÀSb unit occurred, which could be detected by ESI-MS. [33] This rearrangement reveals an astonishing reactivity because all compounds with a{ V 14 of ammonium additives. [72] Under stirring conditions, the transformation could reach full conversion after only 4h at 150 8C, resultingi nf ormation of [{Ni(en) 2 } 2 V 14 Sb 8 O 42 ]·5.5H 2 O [36] featuring the b-isomer of the {V 14 Sb 8 O 42 }m oiety. [73] This fast reaction progress allowed investigation of the conversion by in situ-XRD experiments at the DESY (German Electron Synchotron) facility in Hamburg.…”

“…The power of the Ni-{V 15 Sb 6 } 10 as as ynthon has also been demonstrated by the reaction withG eO 2 ,w hich resulted in a mixed antimonato-germanato polyoxovanadate, namely {Ni(en) 3 [74] In this mixed het-eroatomP OV,S ba nd Ge occupyd istinct positions that might have been formed by partial transformation (Figure 17 from low-nuclearity materials. [72] Compound 12 features ac lose interaction between one nitrogen atom of all three ethylenediamine molecules and three of the Sb atoms with SbÀNd istances significantly shorter than the sum of their van der Waals radii. As was shown recently, such short SbÀNd istances must be treated as covalent bonds with astrength comparable to aSb ÀObond.…”

Room Temperature Synthesis of [Pd(cyclam)]5{H3Nb6O19}2 ⋅ 26H2O: a Suitable Precursor for the in‐situ Generation of a Highly Active Catalyst for Light‐Driven Hydrogen Evolution

“…The group 5 and 6 polyoxometalates (POMs) build cage like cluster anions composed of {MO 6 } octahedra (M=V, Nb, Ta, Mo and W), while V is often observed in a rectangular‐pyramidal VO 5 coordination [1–17] . Polyoxoniobates (PONbs) as a subgroup of POMs exhibit an impressive structural diversity, represented by e. g. the Lindqvist {Nb 6 O 19 } 8− , [18–21] the decaniobate {Nb 10 O 28 } 6− , [22–24] the Keggin {XNb 12 O 40 } n− (X=P, Si, Ge, V) clusters, [25–27] and giant cluster shells like {Nb 114 } [28] or {Nb 288 } [29] .…”