Synthesis of Carbaalane Halogen Derivatives

The carbaalane halogen derivatives [(AlX)6(AlNMe3)2(CCH2CH2SiMe3)6] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)6(AlNMe3)2(CCH2CH2SiMe3)6] (6) and BF3·OEt2, BX3 (X = Br, I), Me3SnF, and Me3SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH)2(AlX)4(AlNMe3)2(CCH2CH2SiMe3)6] (12) (X = Cl (∼40%), Br (∼60%)) was obtained from 5 and impure BBr3. [(AlH)6(AlNMe3)2(CCH2Ph)6] (5) was converted to [(AlX)6(AlNMe3)2(CCH2Ph)6] (X = F (13), Cl (14), Br (15), I (16)) using BF3·OEt2 and Me3SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11·C6H6, 12·3C7H8, 13·6C7H8, and 15·4C7H8 were determined. Compounds 7 and 9−11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents.