Iridium α-carboxyimine complexes hyperpolarized with parahydrogen exist in nuclear singlet states before conversion into iridium carbonates

TY - JOUR

T1 - Iridium α-carboxyimine complexes hyperpolarized with parahydrogen exist in nuclear singlet states before conversion into iridium carbonates

AU - Tickner, Ben J.

AU - Iali, Wissam

AU - Roy, Soumya S.

AU - Whitwood, Adrian C.

AU - Duckett, Simon B.

N1 - © 2018 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. 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 - 2018/9/27

Y1 - 2018/9/27

N2 - The formation and hyperpolarization of an [Ir(H)2(amine)(IMes)(η2-imine)]Cl complex that can be created in a hyperpolarized nuclear singlet state is reported. These complexes are formed when an equilibrium mixture of pyruvate, amine (benzylamine or phenylethylamine), and the corresponding imine condensation product, react with preformed [Ir(H)2(amine)3(IMes)]Cl. These iridium -carboxyimine complexes exist as two regioisomers differentiated by the position of amine. When examined with para-hydrogen the hydride resonances of the isomer with amine trans to hydride become strongly hyperpolarized. The initial hydride singlet states readily transfer to the corresponding 13C2 state in the labelled imine and exhibit magnetic state lifetimes of up to 11 seconds. Their 13C signals have been detected with up to 420 fold signal gains at 9.4 T. On a longer timescale, and in the absence of H2, further reaction leads to the formation of neutral carbonate containing [Ir(amine)(η2-CO3)(IMes)(η2-imine)]. Complexes are characterized by, IR, MS, NMR and X-ray diffraction.

AB - The formation and hyperpolarization of an [Ir(H)2(amine)(IMes)(η2-imine)]Cl complex that can be created in a hyperpolarized nuclear singlet state is reported. These complexes are formed when an equilibrium mixture of pyruvate, amine (benzylamine or phenylethylamine), and the corresponding imine condensation product, react with preformed [Ir(H)2(amine)3(IMes)]Cl. These iridium -carboxyimine complexes exist as two regioisomers differentiated by the position of amine. When examined with para-hydrogen the hydride resonances of the isomer with amine trans to hydride become strongly hyperpolarized. The initial hydride singlet states readily transfer to the corresponding 13C2 state in the labelled imine and exhibit magnetic state lifetimes of up to 11 seconds. Their 13C signals have been detected with up to 420 fold signal gains at 9.4 T. On a longer timescale, and in the absence of H2, further reaction leads to the formation of neutral carbonate containing [Ir(amine)(η2-CO3)(IMes)(η2-imine)]. Complexes are characterized by, IR, MS, NMR and X-ray diffraction.

UR - http://www.scopus.com/inward/record.url?scp=85053910151&partnerID=8YFLogxK

U2 - 10.1002/cphc.201800829

DO - 10.1002/cphc.201800829

M3 - Article

AN - SCOPUS:85053910151

SN - 1439-4235

JO - ChemPhysChem

JF - ChemPhysChem

M1 - cphc.201800829

ER -