Substitution at a Coordinatively Saturated Aluminum Center Stabilized by Imidazolidin-2-imine

In this article, the coordination chemistry of the imidazolidin-2imine ligand (1) toward aluminum has been delineated. We commenced our investigation by preparing dimeric aluminum dihydride {mu-LAlH2}2 (2) from the reaction of 1 with AlH3. Substitution of the hydride with methyl (3), chloride (4), and bromide (7) was achieved from the reaction of 2 with BH3 center dot SMe2, BHCl2 center dot SMe2, and Br2/H2O, respectively. The reaction with BH3 center dot THF afforded a 1 -> BH3 adduct (5) with simultaneous elimination of AlH3. An unprecedented spirocyclic aluminate anion with imidazolidin-2-iminium cation (6) resulted from a reaction with PhB(OH)2. While sulfur undergoes insertion reaction into the Al-H bonds (8), the reactions with diselenides and ditellurides conveniently install unusual functionalities such as -SePh (10) and -TePh (11) onto alane.

Automated summary

This article describes the coordination chemistry of the imidazolidin-2-imine ligand with aluminum. The reaction between the ligand and AlH3 yielded a dimeric aluminum dihydride. Substitution of hydride with various groups such as methyl, chloride, and bromide was achieved through different reactions. Additionally, reactions with different compounds led to the introduction of unusual functionalities onto alane.