Exchange of Alkyl and Tris(2-mercapto-1--butylimidazolyl)hydroborato Ligands Between Zinc, Cadmium and Mercury.

The (2-mercaptoimidazolyl)hydroborato ligand, [Tm ], has been used to investigate the exchange of alkyl and sulfur donor ligands between the Group 12 metals, Zn, Cd and Hg. For example, [Tm ]Zn reacts with MeZn to yield [Tm ]ZnMe, while [Tm ]CdMe is obtained readily upon reaction of [Tm ]Cd with MeCd. Ligand exchange is also observed between different metal centers. For example, [Tm ]CdMe reacts with MeZn to afford [Tm ]ZnMe and MeCd. Likewise, [Tm ]HgMe reacts with MeZn to afford [Tm ]ZnMe and MeHg. However, whereas the [Tm ] ligand transfers from mercury to zinc in the methyl system, [Tm ]HgMe/MeZn, transfer of the [Tm ] ligand from zinc to mercury is observed upon treatment of [Tm ]Zn with HgI to afford [Tm ]HgI and [Tm ]ZnI. These observations demonstrate that the phenomenological preference for the [Tm ] ligand to bind one metal rather than another is strongly influenced by the nature of the co-ligands.