text: Some of the first reported organotantalum complexes were cyclopentadienyl derivatives.  These arise from the salt metathesis reactions of sodium cyclopentadienide and tantalum pentachloride.  An example of this is the first transition metal trihydride, CpTaH.  More soluble and better developed are derivatives of pentamethylcyclopentadiene such as Cp*TaCl, Cp*TaCl, and Cp*TaH.