1H and 13C NMR assignments with coordination‐induced shift calculations of carbon σ‐bonded ortho‐metalated rhodium(III) and iridium(III) complexes

Abstract

AbstractComplete 1H and 13C NMR assignments and coordination‐induced shift [CIS, δ(complex) – δ(free ligand)] calculations for carbon σ‐bonded ortho‐metalated rhodium(III) and iridium(III) complexes are described. NMR parameters are used as probes of van der Waals interactions and ring current anisotropy in the ligand's environmental framework and to monitor σ‐donation and π‐back‐bonding within the ligand in this family of ortho‐metalated complexes. CIS measurements indicate large charge redistribution within the ligands as a result of ortho‐metalation to the rhodium(III) or iridium(III) cationic metal centers. The pulse sequences, attached proton test (APT), 1H1H homonuclear correlation spectroscopy (COSY), single‐frequency off‐resonance decoupling (SFORD) and 1H13C heteronuclear correlation spectroscopy (HETCOR), were utilized to assign all proton and carbon resonances of [Rh(ppy)2Cl]2, [Ir(ppy)2Cl]2, [Ir(ptpy)2Cl]2, [Ir(mppy)2Cl]2, [Rh(ppy)2bpy]+, [Ir(ppy)2bpy]+, [Ir(ptpy)2bpy]+ and [Ir(mppy)2bpy]+, where ppy is 2‐phenylpyridine, ptpy is 2‐(p‐tolyl)pyridine, mppy is 3‐methyl‐2‐phenylpyridine and bpy is 2,2′‐bipyridine.