New Water-Soluble Cluster Compound {Zn(en)3 }3 [V15 Sb6 O42 (H2 O)]⋅ (Ethylenediamine)3 ⋅10 H2 O as a Synthon for the Generation of Two New Antimonato Polyoxovanadates.

A new antimonato polyoxovanadate {Zn(en)3 }3 [V15 Sb6 O42 (H2 O)]⋅3 en⋅10 H2 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 {V14 Sb8 O42 } cluster is observed. The conversion reaches 50 % after 14 days and is complete after approximately 20 days. The rate of this {V15 Sb6 }→{V14 Sb8 } 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)3 }2 [Zn(en)2 V15 Sb6 O42 (H2 O)]⋅23 H2 O after a short reaction time, whereas addition of Sb2 O3 led to fast crystallization of {(Zn(en)2 (H2 O)2 )(Zn(en)2 )}[Zn(en)2 V15 Sb6 O42 (H2 O)] ⋅8.5 H2 O. In the crystal structure of {Zn(en)3 }3 [V15 Sb6 O42 (H2 O)]⋅3 en⋅10 H2 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 [V15 Sb6 O42 (H2 O)]6- anions are expanded by Zn2+ -centered complexes through Zn-O-V bond formation.