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

Reaction of the readily accessible dimethyloctadienyl ruthenium chloride [(mu-eta(3):eta(3)-C10H16)RuCl2](2) (1) with 1,3,5,5-tetramethylcyclohexadiene and arenes in the presence of TlPF6 gives cyclohexadienyl ruthenium arene complexes [(eta(5)-C6H3Me4)Ru(eta(6)-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 [(eta(5)-C6H3Me4)Ru(eta(6)-C6H(3)Me(3))](+) 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 [(eta(5)-C5H5(Bu-i)Me)Ru(eta(6)-C6H4Me2)](+) (6) via isomerization of the dimethyloctadienyl ligand. The structures of [(eta(5)-C6H3Me4)Ru(eta(6)-naphthalene)]PF6 and [6]BPh4 were confirmed by X-ray diffraction. (C) 2014 Elsevier B. V. All rights reserved.