Chalcogen stabilized cubane-type cluster: Synthesis and structure of [(Cp*Ta)(3)(mu-Se)(3)(mu(3)-Se)(3)B(OBuCl)]

In an effort to isolate the heavier chalcogen-rich metallaheteroborane analogue of [(Cp*Ta)(3)(mu-S)(3)(mu(3)-S)(3)BH], thermolysis of [Cp*TaCl4] (Cp* = eta(5)-C5Me5) and Li[BH2Se3] was carried out that afforded cubane-type cluster [(Cp*Ta)(3)(mu-Se)(3)(mu(3)-Se)(3)B(OBuCl)], 1. Compound 1 is an example of cubane-type organotantalum selenido cluster, in which one of the vertices of the cubane is missing. Compound 1 is a hypo-electronic cluster with an electron count of 50 cve (cve = cluster valence electrons). In parallel to the formation of 1, trimetallic selenide cluster [(Cp*Ta)(3)(mu-Se)(6)), 2 has also been isolated and structurally characterized. All these compounds were characterized by the multi-nuclear NMR spectroscopy, mass spectrometry and single crystal X-ray crystallography. The density functional theory (DFT) calculations were also performed to provide insight into the bonding and electronic structures of these novel clusters.