Co5C and Co4C carbido carbonyl clusters stabilized by [AuPPh3]+ fragments

• The synthesis of Co5C and Co4C clusters stabilized by Au(I) fragments is reported.
• Some of them display isomerism in the solid state due to weak forces.
• Unprecedented species have been trapped upon coordination to Au(I).
• Metal carbide clusters are platforms to test aurophilicity.
• Carbonyl clusters may be versatile ligands.

The synthesis and structural characterization of [Co5C(CO)11(AuPPh3)3], 1-A and 1-B, [Co5C(CO)11(AuPPh3)2]−, 2, [Co5C(CO)10(PPh3)2(AuPPh3)], 3, [Co5C(CO)12(AuPPh3)], 4, [Co5C(CO)11(PPh3)(AuPPh3)], 5, and [Co4C(CO)10(AuPPh3)2], 6, is herein reported. Compounds 1–6 have been obtained whilst studying the reactivity of [Co6C(CO)15]2− with [Au(PPh3)Cl] under different experimental conditions, even if better alternative syntheses have been, then, found for some of these new clusters. 1–6 contain the electron precise [Co5C(CO)12]−, [Co5C(CO)11]3− and [Co4C(CO)10]2− clusters, or their PPh3 derivatives, stabilized by [AuPPh3]+ fragments. Two different isomers of 1, i.e., 1-A and 1-B, have been found in the solid state due to solvation effects and weak d10–d10 Au(I)⋯Au(I) aurophilic interactions. 1-A and 4 have been previously described in the literature.

Square pyramidal Co5C and butterfly Co4C carbido carbonyl clusters stabilized by 1–3 [AuPPh3]+ fragments have been obtained. Some of them display isomerism in the solid state due to solvation effects and aurophilic interactions.Figure optionsDownload as PowerPoint slide