Analytical Chemistry and Spectroscopy
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Complete 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.
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