Microwave‐Assisted Synthesis and Transformations of Cationic CpRu(II)(naphthalene) and CpRu(II)(naphthoquinone) Complexes

Details of the direct synthesis of cationic Ru(II)( η 5 ‐Cp)( η 6 ‐arene) complexes from ruthenocene using microwave heating are reported. Developed for the important catalyst precursor [Ru(II)( η 5 ‐Cp)( η 6 ‐1‐4,4a,8a‐naphthalene)][PF 6 ] reaction time could be shortened from three days to 15 min. The method was extended to [Ru(II)( η 6 ‐benzene)( η 5 ‐Cp)][PF 6 ], [Ru(II)( η 5 ‐Cp)( η 6 ‐toluene)][PF 6 ], [Ru(II)( η 5 ‐Cp)( η 6 ‐mesitylene)][PF 6 ], [Ru(II)( η 5 ‐Cp)( η 6 ‐hexamethylbenzene)][PF 6 ], [Ru(II)( η 5 Cp)( η 6 ‐indane)][PF 6 ], [Ru(II)( η 5 ‐Cp)( η 6 ‐2,6‐dimethylnaphthalene)][PF 6 ], and [Ru(II)( η 5 ‐Cp)( η 6 ‐pyrene)][PF 6 ]. 1‐methylnaphthalene and 2,3‐dimethylnaphthalene afforded mixtures of regioisomeric complexes. [Ru(Cp)(CH 3 CN) 3 ][PF 6 ], derived from the naphthalene precursor provided access to the cationic RuCp complexes of naphthoquinone, tetralindione, 1,4‐dihydroxynaphthalene, and 1,4‐dimethoxynaphthalene. Reduction of the tetralindione complex afforded selectively the endo , endo diol derivative. X‐Ray structures of five complexes are reported.