Tantalum(III) chloride
Tantalum chloride or tantalum trichloride is a non-stoichiometric chemical compound with a range of composition from TaCl2.9 to TaCl3.1 Anionic and neutral clusters containing Ta chloride include 4− and 4.
Formation
Tantalum chloride is formed by reducing tantalum chloride with tantalum metal. this is done by heating tantalum chloride to 305 °C, passing the vapour over tantalum foil at 600°, and condensing the trichloride at 365 °C. If the condensing region is kept at too high a temperature, then TaCl2.5 deposits instead.The trichloride can also be prepared by thermal decomposition of TaCl4, with removal of volatile TaCl5. TaCl5 can be vapourised leaving behind TaCl3.
"Salt-free reduction" of a toluene solution of TaCl5 with 1,4-disilyl-cyclohexadiene in the presence of ethylene produces a complex of TaCl3:
Properties
Above 500 °C, TaCl3 disproportionates further releasing TaCl5. TaCl3 is insoluble in room temperature water, or dilute acid, but dissolves in boiling water. A blue-green solution is formed.Complexes
Tantalum chloride can form complexes with some ligands as a monomer or dimer.Complexes include Ta2Cl3, 2μ-N2 and 2μ-N2.
As a dimer, complexes include Ta2Cl63. Ta2Cl63, Ta2Cl63 and Ta2Cl63 have a double bond between the two tantalum atoms, and two bridging chlorides, and a bridging ligand.