Hafnium sulfoxide complexes

Table 15 Complexes of Ziiconium(IV) and Hafnium(IV) Halides with Sulfoxides, Selenoxides, Amides, Af-Oxides, P-Oxides and Related Ligands...

The proton NMR spectra of the tetrakistropolonates of zirconium and hafnium in dimethyl sulfoxide has also been examined. The spectra are consistent with a complex in which all four ligands are equivalent, but there is no evidence for rapid exchange between the chelates and free ligands (379). Similarity in chemical shifts for the tropolone and chelate resonances, however, makes a definitive statement difficult. Attempts to form a 10-coordinate species with tropolone were unsuccessful (377). 

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