Synthesis of the cyclohexadienyl ruthenium arene complexes [(η5-C6H3Me4)Ru(η6-arene)]+ from the dimethyloctadienyl ruthenium chloride[(μ-η3:η3-C10H16)RuCl2]2

•A new approach to substituted cyclohexadienyl ruthenium arene complexes was developed.•Tetramethylcyclohexadienyl ligand can undergo C–Me bond cleavage to give mesitylene.•Dimethyloctadiendiyl ligand can be transformed into substituted pentadienyl ligand.

Reaction of the readily accessible dimethyloctadienyl ruthenium chloride [(μ-η3:η3-C10H16)RuCl2]2 (1) with 1,3,5,5-tetramethylcyclohexadiene and arenes in the presence of TlPF6 gives cyclohexadienyl ruthenium arene complexes [(η5-C6H3Me4)Ru(η6-arene)]+ in ca. 50% yield (arene = benzene, naphthalene, pyrene, thiophene, ethyl ester of N-acetyl-phenylalanine). In the absence of appropriate arene the major product is the mesitylene complex [(η5-C6H3Me4)Ru(η6-C6H3Me3)]+ formed via splitting of the C–Me bond in the 1,3,5,5-tetramethylcyclohexadienyl ligand. The reaction of 1 with p-xylene and TlPF6 in the absence of diene gives a methyl-isobutyl substituted pentadienyl complex [(η5-C5H5(iBu)Me)Ru(η6-C6H4Me2)]+ (6) via isomerization of the dimethyloctadienyl ligand. The structures of [(η5-C6H3Me4)Ru(η6-naphthalene)]PF6 and [6]BPh4 were confirmed by X-ray diffraction.

Graphical abstractA variety of cyclohexadienyl ruthenium arene complexes were synthesized from the readily available precursors: chloride [(C10H16)RuCl2]2 and tetramethylcyclohexadiene.Figure optionsDownload full-size imageDownload as PowerPoint slide