Zirconium sulfoxide complexes

The complications which result from the hydrolysis of alkali metal cyanides in aqueous media may be avoided by the use of non-aqueous solvents. The one most often employed is liquid ammonia, in which derivatives of some of the lanthanides and of titanium(III) may be obtained from the metal halides and cyanide.13 By addition of potassium as reductant, complexes of cobalt(O), nickel(O), titanium(II) and titanium(III) may be prepared and a complex of zirconium(0) has been obtained in a remarkable disproportion of zirconium(III) into zirconium(IV) and zirconium(0).14 Other solvents which have been shown to be suitable for halide-cyanide exchange reactions include ethanol, methanol, tetrahydrofuran, dimethyl sulfoxide and dimethylformamide. With their aid, species of different stoichiometry from those isolated from aqueous media can sometimes be made [Hg(CN)3], for example, is obtained as its cesium salt form CsF, KCN and Hg(CN)2 in ethanol.15... 

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). 

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

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