Synthesis and Structural Characterization of Tris(2-mercapto-1-adamantylimidazolyl)hydroborato Complexes: A Sterically Demanding Tripodal [S3] Donor Ligand

The tris(2-mercapto-1-adamantylimidazolyl)hydroborato ligand, [TmAd], has been synthesized via the reaction of 1-adamantyl-2-mercaptoimidazole with MBH4 (M = Li, K). [TmAd]M has been used to synthesize a variety of compounds of the main-group and transition elements, including [TmAd]ZnI, {[TmAd]GaI}[GaI4], {[TmAd]GaCl}[GaCl4], {[TmAd]GaGa[TmAd]}[GaCl4]2, {[TmAd]2In}[InI4], [TmAd]In(κ2-mimAd)Cl, [TmAd]Ga→B(C6F5)3, [TmAd]In→B(C6F5)3, and [TmAd]Re(CO)3. Structural characterization of [TmAd]Re(CO)3 demonstrates that the [TmAd] ligand is more encapsulating than other [TmR] ligands, including [TmBut], while IR spectroscopic studies indicate that the [TmAd] and [TmBut] ligands have very similar electron-donating properties.