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

The tris(2-mercaptoimidazolyl)hydroborato ligand, [TmBut ], has been used to investigate the exchange of alkyl and sulfur donor ligands between the Group 12 metals, Zn, Cd and Hg. For example, [TmBut ]2Zn reacts with Me2Zn to yield [TmBut ]ZnMe, while [TmBut ]CdMe is obtained readily upon reaction of [TmBut ]2Cd with Me2Cd. Ligand exchange is also observed between different metal centers. For example, [TmBut ]CdMe reacts with Me2Zn to afford [TmBut ]ZnMe and Me2Cd. Likewise, [TmBut ]HgMe reacts with Me2Zn to afford [TmBut ]ZnMe and Me2Hg. However, whereas the [TmBut ] ligand transfers from mercury to zinc in the methyl system, [TmBut ]HgMe/Me2Zn, transfer of the [TmBut ] ligand from zinc to mercury is observed upon treatment of [TmBut ]2Zn with HgI2 to afford [TmBut ]HgI and [TmBut ]ZnI. These observations demonstrate that the phenomenological preference for the [TmBut ] ligand to bind one metal rather than another is strongly influenced by the nature of the co-ligands.