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

Abstract

Indenyl-(Ind) and fluorenyl-(Fl) substituted NHC-stabilized alanes and gallanes (NHC)·EH₂R 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)·AlHR₂13–18 (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)·AlH₂}₂-μ-Fl 19–20 and {(NHC)·AlH-μ-R}_n21–23 (R = Ind, Fl; n = 2, 3) with bridging indenyl and fluorenyl ligands.