Long‐Term Generation of Longitudinal Spin Order Controlled by Ammonia Ligation Enables Rapid SABRE Hyperpolarized 2D NMR

Symmetry breaking of parahydrogen using iridium catalysts converts singlet spin order into observable hyperpolarization. In this contribution, are designed to exhibit asymmetry in their hydrides, regulated by situ generation deuterated ammonia governed ammonium buffers. The concentrations (N) and pyridine (P) provide a handle generate variety stereo-chemically asymmetric N-heterocyclic carbene complexes, ligating either [3xP], [2xP;N], [P;2xN] or [3xN] an octahedral SABRE type configuration. non-equivalent hydride positions, correspondence with the buffer solutions, enables extend singlet-triplet mixing at high magnetic field experimentally induce prolonged non-equilibrium longitudinal two-spin order. This long-lasting magnetization can be exploited hyperpolarized 2D-OPSY-COSY experiments providing direct structural information on catalyst single contact parahydrogen. Separately, cycling revealed hyperpolarization properties low-field conditions. Controlling stereochemistry introducing small ligands, such as ammonia, simplifies spin-system. is shown unify experimental theoretically derived field-sweep for four-spin systems.