In an effort to synthesize chalcogen-rich metallaheteroborane clusters of group 5 metals, thermolysis of [Cp*TaCl4] (Cp* = eta(5)-C5Me5) with thioborate ligand Li[BH2S3] was carried out, affording trimetallic clusters [(Cp*Ta)(3)(mu-S)(3)(mu(3)-S)(3)B(R)], 1-3 (1, R = H; 2, R = SH; and 3, R = Cl). Clusters 1-3 are illustrative examples of cubane-type organotantalum sulfido clusters in which one of the vertices of the cubane is missing. In parallel to the formation of 1-3, the reaction also yielded tetrametallic sulfido cluster [(Cp*Ta)(4)(mu-S)(6)(mu(3)-S)(mu(4)-O)], 6, having an adamantane core structure. Compound 6 is one of the rarest examples containing the mu(4)-oxo unit with a heavier early transition metal, i.e., tantalum. In an effort to isolate selenium analogues of clusters 1-3, we have isolated the trimetallic cluster [(Cp*Ta)(3)(mu-Se)(3)(mu(3)-Se)(3)B(H)], 4, from the thermolytic reaction of [Cp*TaCl4] and Li[BH2Se3]. In contrast, the thermolysis of [Cp*TaCl4] with Li[BH2Te3] under the same reaction conditions yielded tantalum telluride complex [(Cp*Ta)(2)(mu-Te)(2)], 5. Compounds 1-4 are hypo-electronic clusters with an electron count of 50 cluster valence electrons. All these compounds have been characterized by H-1, B-11{H-1}, and C-13{H-1} NMR spectroscopy; infrared spectroscopy; mass spectrometry; and single-crystal X-ray crystallography. The density functional theory calculations were also carried out to provide insight into the bonding and electronic structures of these molecules.