Synthesis and structure of a tantalum(V) tetrakis-O,O chelate:: [Ta(tmhd)4][TaCl6]

Reaction of TaCl5 with neat tmhdH (2,2,6,6-tetramethylheptane-3,5-dione) (in the absence of solvent) yields the ionic compound [Ta(tmhd)(4)] [TaCl6]. This complex contains the eight coordinate Ta(V) cation, [Ta(tmhd)(4)](+), accompanied by the hexachlorotantalate anion, [TaCl6](-). This is the first complex of tantalum in the +5 oxidation state containing four chelating diketonate anions to be characterised using X-ray crystallography. (c) 2005 Elsevier B.V. All rights reserved.