Self-assembly of a tetrahedral 58-nuclear barium vanadium oxide cluster

We report the synthesis and characterization of a molecular barium vanadium oxide cluster featuring high nuclearity and high symmetry. The tetrameric, 2.3 nm cluster H-5[Ba-10(NMP)(14)(H2O)(8)[V12O33](4)Br] is based on a bromide-centred, octahedral barium scaffold which is capped by four previously unknown [V12O33](6-) clusters in a tetrahedral fashion. The compound represents the largest polyoxovanadate-based heterometallic cluster known to date. The cluster is formed in organic solution and it is suggested that the bulky N-methyl-2-pyrrolidone (NMP) solvent ligands allow the isolation of this giant molecule and prevent further condensation to a solid-state metal oxide. The cluster is fully characterized using single-crystal XRD, elemental analysis, ESI mass spectrometry and other spectroscopic techniques.