The pentamethylcyclopentadienyl−aminoborole chloro complexes Cp*{η^5-C_4H_4BN(CHMe_2)_2}MCl·LiCl (Cp* = (η^5-C_5Me_5); M = Zr, Hf) heterolytically cleave H−X bonds to form Cp*{η^5-C_4H_4BNH(CHMe_2)_2}MCl(X) (X = OR, SR, C⋮CR). Control experiments using deuterium-labeled substrates show heterolysis occurs with no incorporation of deuterium into the 2,5 positions of the borole heterocycle. Cp*{η^5-C_4H_4BNH(CHMe_2)_2}Hf(C⋮CSiMe_3)_2 is prepared from Cp*{η^^5-C_4H_4BN(CHMe_2)_2}Hf(η^3-C_3H_5) and 2 equiv of (trimethylsilyl)acetylene. Treatment of Cp*{η^5-C_4H_4BN(CHMe_2)_2}MCl·LiCl (M = Zr, Hf) with donor ligands L yields the LiCl-free complexes Cp*{η^5-C_4H_4BN(CHMe_2)_2}MCl(L) (M = Zr, L = NMe2H; M = Hf, L = PMe_3). Cp*{η^5-C_4H_4BN(CHMe_2)_2}HfCl(PMe_3) reacts with (trimethylsilyl)acetylene with loss of HN(CHMe_2)_2 to form Cp*{η^5-C_4H_4B(C⋮CSiMe_3)}HfCl(PMe_3), resulting from formal migration of acetylide from hafnium to boron. X-ray structure determinations of Cp*{η^5-C_4H_4BNH(CHMe_2)_2}HfCl(C⋮CSiMe_3), Cp*{η^5-C_4H_4BN(CHMe_2)_2}HfCl(PMe_3), and Cp*{η^5-C_4H_4B(C⋮CSiMe_3)}HfCl(PMe_3) are reported
