The tris(2-mercapto-1-methylbenzimidazolyl)hydroborato cadmium
complex, {[TmMeBenz]Cd(μ–Br)}2, may be synthesized
via the reaction of [TmMeBenz]K with CdBr2. X-ray
diffraction demonstrates that {[TmMeBenz]Cd(μ–Br)}2
exists as a dimer, which is in marked contrast to the monomeric structure of the
non-benzannulated counterpart, [TmMe]CdBr, and thereby demonstrates that
benzannulation of tris(2-mercapto-1-methylbenzimidazolyl)hydroborato
ligands can have a distinct impact on the molecular structure of their metal complexes. In
accord with this observation, density functional theory calculations indicate that the
benzannulated dimers, {[TmMeBenz]Cd(μ–X)}2 (X = Cl,
Br, I), are more stable with respect to dissociation than are their non-benzannulated
counterparts, {[TmMe]Cd(μ–X)}2. Furthermore, the
calculations also indicate that the stability of the dimer depends on the nature of X,
such that the dimer becomes more stable in the sequence I < Br < Cl.