Homoleptic and heteroleptic Au(i) complexes containing the new [Co5C(CO)12]− cluster as ligand

The new [{Co5C(CO)(12)}Au{Co(CO)(4)}](-), [1](-), cluster has been obtained from the reaction of [Co6C(CO)(15)](2)(-) with two equivalents of [AuCl4](-). [1](-) reacts with an excess of HBF4 resulting in the formation of [{Co5C(CO)(12)}(2)Au](-), [2](-). The new derivatives [Co5C(CO)(12)(AuPPh3)], 3, and [Co5C(CO)(11)(AuPPh3)(3)], 4, have been obtained by reacting [2](-) with two and four equivalents of [Au(PPh3)Cl], respectively. All the new species have been structurally characterised by means of X-ray crystallography as their [NEt4][1], [NEt4][2], [NMe3(CH2Ph)][2], 3 and 4 center dot thf center dot 0.5C(6)H(14) salts and solvates. [2](-) may be viewed as a homoleptic Au(I) complex containing two [Co5C(CO)(12)](-) clusters as ligands. Similarly, [1](-) and 3 are heteroleptic Au(I) complexes containing one [Co5C(CO)(12)](-) cluster ligand as well as [Co(CO)(4)](-) or PPh3. Conversely, 4 contains the [Co5C(CO)(11)](3)(-) cluster stabilized by three [AuPPh3](+) fragments. [1](-) and [2](-) have been investigated in solution by means of electrochemical and spectroelectrochemical methods, revealing a very rich redox propensity to form the closely related [1](n-) (n = 1-3) and [2](n-) (n = 0-3) species.