Synthesis and Characterization of a Novel Tantalum Chalcogen-Rich Molecular Cluster with Square Planar Metal Core

Black single crystals of Ta4Se9I8 are obtained in a high yield by
heating Ta, Se, and I2 at 300 °C in 1:2.2:1.0 molar ratio. In the
structure, the tantalum atoms form a square, with four Se2 ligands
bridging the Ta−Ta edges and one capping the square. Each Ta
atom has two terminal iodine atoms. The compound is diamagnetic
and has only two electrons for metal−metal bonding.