NHC-ligated indenyl- and fluorenyl-substituted Alanes and Gallanes: synthons towards indenyl- and fluorenyl-bridged (AlC) n -heterocycles ( n = 2,3).

Indenyl-(Ind) and fluorenyl-(Fl) substituted NHC-stabilized alanes and gallanes (NHC)·EH 2 R 1-12 (NHC = IiPr Me , IiPr, IMe Me ; E = Al, Ga; R = Ind, Fl) were prepared via reaction of the corresponding NHC-iodoalanes and -gallanes with LiInd and LiFl, respectively. Analogously, the alane adducts with two Ind/Fl substituents (NHC)·AlHR 2 13-18 (NHC = IiPr Me , IiPr, IMe Me ; R = Ind, Fl) were obtained by using two equivalents of LiInd/LiFl. Elimination of indene and fluorene was induced thermally affording unusual dimeric and trimeric NHC-alane adducts {(NHC)·AlH 2 } 2 -μ-Fl 19-20 and {(NHC)·AlH-μ-R} n 21-23 (R = Ind, Fl; n = 2, 3) with bridging indenyl and fluorenyl ligands.