Reaction between [Ir(COD)(PMe3)3]Cl and 2-aminopent-4-enoic acid: Tridentate N, O and C bonding

• 2-Aminopent-4-enoic acid reaction with iridium(I) is unusual.
• Hydride formation followed immediately by alkene insertion is shown.
• A C, N, O tripodal multidentate ligand binding is described.
• Multiple forms of hydrogen-bonding in the crystal state are discussed.

The reaction between the electron-rich iridium(I) complex, [Ir(COD)(PMe3)3]Cl, and the amino acid, 2-aminopent-4-enoic acid leads to the direct formation of a product with facial geometry about the iridium center with three PMe3 groups, and tripodal coordination of the amino acid via N, O and C. The synthesis of this product can be visualized as involving the formation of an iridium hydride followed by insertion of the pendant alkene. Two different crystal structures of the product were determined, one containing a chloride counterion and one with a tetraphenylborate counterion. The change in counterion leads to very different intermolecular interactions.

Reaction between [Ir(COD)(PMe3)3]Cl and 2-aminopent-4-enoic acid leads to a product with facial geometry of three PMe3 groups about iridium, and tripodal coordination of the amino acid via N, O and C. The N–H atoms H-bond to the chloride. With BPh4−, the H-bonding motif is a one-dimensional chain linked by N⋯H⋯O interactions.Figure optionsDownload as PowerPoint slide