Reaction of the NHC-stabilized mono- and bis-iodo-alanes with NaCp afforded the corresponding Cp-substituted compounds that show dismutation in solution. Using magnesocene MgCp₂ as Cp source led to isolation of tetranuclear Al₂Mg₂ compounds with interesting structural motifs including bridging hydrides between Al and Mg centers.

Abstract

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.