Spontaneous transfer of parahydrogen derived spin order to pyridine at low magnetic field

When parahydrogen is used as a source of nuclear spin polarization, spontaneous magnetization transfer has proceeded in low magnetic field from the two nascent hydride ligands of the dihydride complex fac,cis-[Ir(P[Cy.sub.3])[(py).sub.3][(H).sub.2]]B[F.sub.4] to its other NMR active nuclei. The degree of signal enhancement in the free substrate is increased by using electronically rich and sterically encumbered phosphine ligands such as P[Cy.sub.3], P[Cy.sub.2]Ph, or P[super i][Pr.sub.r] and by optimizing the strength of the magnetic field in which polarization transfer occurs.