Activation of M-Cl bonds with phosphine-alanes: Preparation and characterization of zwitterionic gold and copper complexes
Résumé
The triphosphine-alane [iPr2P(o-C6H 4)]3Al (1) was prepared by coupling ortho-lithiated diisopropylphenylphosphine with AlCl3. Reactions of 1 with gold and copper chlorides afforded the zwitterionic cage complexes 2 and 3. The three phosphine arms coordinate symmetrically to the coinage metal, while the aluminum center abstracts the chloride. Coordination of the related diphosphine-alane [iPr2P(o-C6H4)]2AlCl (4) to CuCl is also accompanied by a shift of the chloride atom from copper to aluminum. However, the ensuing highly electrophilic Cu+ center engages in weak intra- and intermolecular Cl→Cu interactions, resulting in the original polymeric complex 5. The structures of all complexes have been ascertained spectroscopically and crystallographically, and their bonding situations have been analyzed by DFT calculations. © 2013 American Chemical Society.