¹¹B NMR:  A New Tool for the Determination of Hapticity of Tris(pyrazolyl)borate Ligands

While X-ray crystallography provides reliable solid-state information, the assignment of hapticity in [HB(3,5-dimethylpyrazolyl) 3 ]ML n (M = Rh, Ir, Pt) complexes in solution is complicated by the dynamic nature of the tris(pyrazolyl)borate ligand. 1 H and 13 C NMR spectroscopy is ambiguous as to the nature of the coordination environment around the metal center. 11 B NMR data are shown to correlate with the hapticity of the tris(pyrazolyl)borate ligand, making it a useful tool for the rapid determination of solution-state structure of tris(pyrazolyl)borate metal complexes.