Ta(CNDipp)6, Dipp = 2,6-diisopropylphenyl: An Isocyanide Analog of Hexacarbonyltantalum(0)

Hexakis(2,6-diisopropylphenylisocyanide)tantalum, (1), is the first isocyanide analog of the highly unstable hexacarbonyltantalum(0), and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta(0) complexes are known, bis(benzene)tantalum and tris(1,2-bis(dimethylphosphano)ethane)tantalum, but these have only been accessed via ligand condensation with tantalum vapor in a sophisticated metal atom reactor. Consistent with its 17-electron nature, compound (1) undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, (1) qualitatively resembles hexacarbonylvanadium(0), the only paramagnetic metal carbonyl isolable under ambient conditions.