Iridium Cyclooctene Complex Forms a Hyperpolarization Transfer Catalyst Before Converting to a Binuclear C-H Bond Activation Product Responsible for Hydrogen Isotope Exchange

TY - JOUR

T1 - Iridium Cyclooctene Complex Forms a Hyperpolarization Transfer Catalyst Before Converting to a Binuclear C-H Bond Activation Product Responsible for Hydrogen Isotope Exchange

AU - Iali, Wissam

AU - Duckett, Simon

AU - Green, Gary George Reginald

AU - Hart, Sam J.

AU - Whitwood, Adrian C.

N1 - © 2016, American Chemical Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2016/11/9

Y1 - 2016/11/9

N2 - [IrCl(COE)2]2 (1) reacts with pyridine and H2 to form crystallo-graphically characterized IrCl(H)2(COE)(py)2 (2). 2 undergoes pyridine loss to form 16-electron IrCl(H)2(COE)(py) (3) with equivalent hydride ligands. When this reaction is studied with parahydrogen, 1 efficiently achieves the hyperpolarization of free pyridine (and nicotinamide, nicotine, 5-aminopyrimidine and 3,5-lutudine) via signal amplification by reversible exchange (SABRE) and hence reflects a simple and readily available precatayst for this process. 2 reacts further over 48 hrs at 298 K to form crystallographically characterized (Cl)(H)(py)(μ-Cl)(μ-H)(κ-μ-NC5H4)Ir(H)(py)2 (4). This dimer is shown to be active in the hydrogen isotope exchange process that is used in radiophar-maceutical preparations. Furthermore, while [Ir(H)2(COE)(py)3]PF6 (6) forms on addition of AgPF6 to 2, its stability precludes its efficient involvement in SABRE.

AB - [IrCl(COE)2]2 (1) reacts with pyridine and H2 to form crystallo-graphically characterized IrCl(H)2(COE)(py)2 (2). 2 undergoes pyridine loss to form 16-electron IrCl(H)2(COE)(py) (3) with equivalent hydride ligands. When this reaction is studied with parahydrogen, 1 efficiently achieves the hyperpolarization of free pyridine (and nicotinamide, nicotine, 5-aminopyrimidine and 3,5-lutudine) via signal amplification by reversible exchange (SABRE) and hence reflects a simple and readily available precatayst for this process. 2 reacts further over 48 hrs at 298 K to form crystallographically characterized (Cl)(H)(py)(μ-Cl)(μ-H)(κ-μ-NC5H4)Ir(H)(py)2 (4). This dimer is shown to be active in the hydrogen isotope exchange process that is used in radiophar-maceutical preparations. Furthermore, while [Ir(H)2(COE)(py)3]PF6 (6) forms on addition of AgPF6 to 2, its stability precludes its efficient involvement in SABRE.

U2 - 10.1021/acs.inorgchem.6b02560

DO - 10.1021/acs.inorgchem.6b02560

M3 - Article

SN - 0020-1669

SP - 1

EP - 5

JO - Inorganic Chemistry

JF - Inorganic Chemistry

ER -