Five-coordinate iridium(iii) complex with ΔΛ chirality. Issue 38 (1st September 2021)

• Record Type: Journal Article
• Authors: Takimoto, Kazuyoshi; Watanabe, Yutaka; Yoshida, Jun; Sato, Hisako
• Is Part Of: Dalton transactions. Volume 50:Issue 38(2021)
• Page Start: 13256
• Page End: 13263
• Publication Date: 2021-09-01
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt01960k
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The present work reports the first example of a chiral five-coordinate bis-chelate Iridium(iii ) complex. The practical significance of the work was demonstrated by the relatively moderate reactivity with small molecules such as carbon monoxide. Abstract : The coordinatively unsaturated bis-chelated iridium(iii ) complex, [Ir(2-Bubzq)2 Cl] (2-BubzqH = 2-butyl-benzo[ h ]quinoline), denoted as complex 1, was obtained by reacting iridium(iii ) trichloride with 2-BubzqH in a 1 : 2 molar ratio. The results were in contrast to the common view that a chlorine-bridged dimer, [Ir(L)2 Cl]2 (L = bis-chelate ligand), is formed under the corresponding conditions. A single-crystal X-ray diffraction structural analysis revealed that complex 1 has a five-coordinate geometry with a distorted square pyramidal configuration. The optical resolution of complex 1 was measured chromatographically on a chiral column, yielding Δ and Λ as enantiomers. The resolved enantiomers were stable enough against racemization in CDCl3 as confirmed by the vibrational circular dichroism measurements. Complex 1 reacted with carbon monoxide (CO) to give [Ir(2-Bubzq)2 (CO)Cl] and with 1, 10-phenanthroline (phen) to give [Ir(2-Bubzq)2 (phen)]Cl within a minute with its absolute configuration (ΔΛ chirality) maintained.