Complexes with carboranyl ligands

The synthesis of salts with the anionic gold (I) complexes [1-(Ph₃PAu)-closo-1-CB₁₁H₁₁]⁻, [1-(Ph₃PAu) -closo-1-CB₉H₉]⁻ and [2-(Ph₃PAu)-closo-2-CB₉H₉]⁻ are the first examples of transition metal complexes of the dianions [closo-1-CB₁₁H₁₁]²⁻, [closo-1-CB₉H₉]²⁻ and [closo-2-CB₉H₉]²⁻ with a two-center two-electron metal C_cluster σ bond. Syntheses for analogue complexes with carba-closo-borate dianions, which also carry functional groups on the boron atoms, are currently being developed. The long-term goal of these studies is to produce coordination polymers and metal macrocycles with linkers that carry anionic boron clusters in the backbone.

Deprotonation of the anions [1-H-closo-1-CB₁₁X₁₁]⁻ (X = H, F, Cl, Br) and reaction with HgCl₂ yielded the dianions [Hg (closo-1-CB₁₁X₁₁)₂]²⁻ and allowed them to be isolated as Cs⁺ and [Et₄N]⁺ salts. In contrast to [Hg (closo-1-CB₁₁X₁₁)₂]²⁻ (X = H, Cl, Br), a third ligand is coordinated to the Hg atom of [Hg (closo-1-CB₁₁F₁₁)₂]²⁻, which is another example of the unusual properties of highly fluorinated {closo-1-CB₁₁} clusters.