NHC-Adducts of Cyclopentadienyl-Substituted Alanes

The mono- and bis-iodo-substituted NHC-stabilized alanes (NHC) ⋅ AlH₂I and (NHC) ⋅ AlHI₂ offer a convenient entry for further substitution reactions at aluminum. Reactions of (NHC) ⋅ AlH₂I 1 – 4 with one equivalent of NaCp afforded the adducts (NHC) ⋅ AlH₂Cp 9 – 12 (NHC=Me₂Im^Me ( 9 ), iPr₂Im^Me ( 10 ), iPr₂Im ( 11 ), Dipp₂Im ( 12 )). Alane adducts with two Cp substituents (NHC) ⋅ AlHCp₂ 13 – 16 (NHC=Me₂Im^Me ( 13 ), iPr₂Im^Me ( 14 ), iPr₂Im ( 15 ), Dipp₂Im ( 16 )) were prepared by the analogous reaction of (NHC) ⋅ AlHI₂ 5 – 8 using two equivalents of NaCp. The unusual dimeric adducts ((NHC) ⋅ AlH₂Cp ⋅ CpMgI)₂ 17 – 19 (NHC=Me₂Im^Me ( 17 ), iPr₂Im^Me ( 18 ), iPr₂Im ( 19 )) were obtained from the reaction of 1 – 3 with MgCp₂.