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.

Graphical abstractSquare 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 full-size imageDownload as PowerPoint slide